sorry this is late... you know how it is, conferences, holidays, workshops, holidays... it hasn't changed, anyway. pws Archive-Name: unix-faq/shell/zsh Last-Modified: 1995/7/18 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zsh.FAQ,v 2.5 1995/07/18 15:26:20 pypeters Exp pypeters $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995 (see end of document) This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. In fact, zsh is currently the most powerful freely available shell. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question A5); if you want to know what to do with insoluble problems, go to Z2). Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Section A: Introducing zsh and how to install it A0) Sources of information A1) What is it? A2) What is good at? A3) On what machines will it run? (Plus important compilation notes) A4) What's the latest version? A5) Where do I get it? A6) I don't have root access: how do I make zsh my login shell? Section B: How does zsh differ from...? B1) sh and ksh? B2) csh? B3) Why do my csh aliases not work? (Plus other alias pitfalls.) B4) tcsh? B5) bash? B6) Shouldn't zsh be more/less like ksh/(t)csh? Section C: How to get various things to work C1) How do I turn off spelling correction for an individual command? C2) How do I get the meta key to work on my xterm? C3) Why does my terminal act funny in way x? C4) Why does `$var' where var="foo bar" not do what I expect? C5) Why do my autoloaded functions not autoload [the first time]? C6) How does base arithmetic work? C7) How do I get a newline in my prompt? C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? C9) Why can't I bind \C-s and \C-q any more? C10) How do I execute command `foo' within function `foo'? C11) Why do history substitutions with single bangs do something funny? C12) Why does zsh kill off all my background jobs when I logout? Section D: The mysteries of completion D1) What is completion? D2) What sorts of things can be completed? D3) How does zsh deal with ambiguous completions? D4) How do I get started with programmable completion? D5) And if programmable completion isn't good enough? Section Z: The future of zsh Z1) What bugs are currently known and unfixed? Z2) Where do I report bugs, get more info / who's working on zsh? Z3) What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Section A: Introducing zsh and how to install it A0) Sources of information Information on zsh is now available via the World Wide Web. The URL is "http://www.mal.com/zsh/". The server provides this FAQ and much else (thanks to Mark Borges for this). The FAQ is at "http://www.mal.com/zsh/FAQ/". Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question A5). Note that if you are reading this file with GNU Emacs 19 and have my cross-referencing package xref.el (soon to be part of Emacs, but currently available from http://python.swan.ac.uk/~pypeters/comp/xref.html), you can pick up a version of this FAQ which is internally cross-referenced from: http://python.swan.ac.uk/~pypeters/comp/zsh.FAQ (As a lower-tech method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question Z2). A1) What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh), although it is not completely compatible. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question Z2). Zsh is distributed under a standard Berkelely style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. A2) What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major feature in any other freely-available shell which zsh does not also have. Command line editing: programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), multi-line commands editable as a single buffer (even files!), variable editing (vared), command buffer stack, print text straight into the buffer for immediate editing (print -z), execution of unbound commands, menu completion, variable, editing function and option name completion, inline expansion of variables, history commands. Globbing --- extremely powerful, including: recursive globbing (cf. find), file attribute qualifiers (size, type, etc. also cf. find), full alternation and negation of patterns. Handling of multiple redirections (simpler than tee). Large number of options for tailoring. Path expansion (=foo -> /usr/bin/foo). Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). Named directories. Comprehensive integer arithmetic. Manipulation of arrays (including reverse subscripting). Spelling correction. A3) On what machines will it run? Zsh was written for machines of the Berkeley UNIX family; most such machines (and all the most popular) will run it without major surgery. Modifications have been made so that it works under SYSVR4-based operating systems such as Solaris 2.x and OSF/1. The best thing is to suck it and see. Success has been obtained on older SYSVR3 systems, but you may need to modify the code. From version 2.6, the installation mechanism has recently been altered to use GNU Autoconf, which should make it easier to recognise new machine types. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in to configure zsh automatically, then send the required context diffs to the list (see question Z2). To get it to work, retrieve the source distribution (see question A5), un-gzip it, un-tar it and read the INSTALL file in the top directory. Here are a couple of known installation problems at present. *Note for Solaris 2.2 and 2.3*: The UCB versions of the routines for reading directories are not usable (the struct definitions are incompatible with the ones assumed by zsh). Make sure you compile without any reference to /usr/ucblib in (e.g.) your LD_LIBRARY_PATH. The symptom of this is that globbed filenames will be missing the first two letters. *Note for OSF/1 3.0*: There is apparently a bug in the header file /usr/include/rpcsvc/ypclnt.h; the prototype for yp_all() has a struct ypall_callback as its final argument, which should be a pointer (struct ypall_callback *). This prevents compilation of zle_tricky.c. If you can't modify the header file, copy it to the current directory, modify that copy, and put a `-I.' argument into CFLAGS in Makefile for the Src subdirectory when compiling. A4) What's the latest version? Zsh 2.5.0 was the last major release: the final form is 2.5.03. Many bugs were fixed after 2.3.1, which was the previous major release, and there were many new features, notably programmable completion. This version is known to have a bug with pipelines inside other shell structures (now fixed in 2.6). Work has now started on 2.6 and 2.6-beta9 is available; note that even numbered minor versions are not released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question Z1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives. A5) Where do I get it? Richard Coleman <zsh@math.gatech.edu> is in charge of the archive. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. USA ftp://ftp.math.gatech.edu/pub/zsh ftp://ftp.sterling.com/zsh ftp://ftp.rge.com/pub/zsh France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh UK ftp://mrrl.lut.ac.uk/zsh (also by FSP at port 21) Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh Norway ftp://ftp.uit.no/pub/unix/shells/zsh Australia ftp://ftp.ips.oz.au/pub/packages/zsh (If you don't understand URL's, the first thing after the ftp:// is the hostname and the remainder after the / is the directory.) The latest full release is in zsh.tar.gz in these directories. Note that this is in gzip format: you will need GNU gzip from your nearest GNU archive to unpack it. The up-to-the-minute development version is in zsh-beta.tar.gz. There is also a version under RCS control which may be more suitable for source hackers. A6) I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the -l tells zsh it is a login shell). It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as '-zsh', you can link zsh to -zsh (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure -zsh is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Section B: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. B1) Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh. Various options can be turned on which will increase ksh compatibility, though decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_OPTION_PRINT, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, SH_WORD_SPLIT (see question C4) and SINGLE_LINE_ZLE. Of these, SH_WORD_SPLIT and NO_NOMATCH are the most likely to spoil your ksh scripts if unset. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh'. Capitalised words with underlines refer to shell options. Syntax: * Shell word splitting: see question C4). (This is particularly frequently asked about; use SH_WORD_SPLIT.) Arrays are more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. Coprocesses are established by `coproc'; `|&' behaves like csh. Opening for both input and output via <> is not yet supported. (This syntax does numeric globbing.) Command line substitutions, globbing etc.: * Failure to match a globbing pattern causes an error (use NO_NOMATCH). * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but * in zsh. (GLOB_SUBST has just been added to fix this.) On the other hand, `foo=*' does globbing immediately on the right hand side of the assignment (the default behaviour may change). The $((...)) version of numeric evaluation was not available before version 2.6 (use $[...]). $PSn do not do parameter substitution by default (use PROMPT_SUBST: this still needs some fixing for complex substitutions). Globbing does not allow ksh-style `pattern-lists'. Equivalents: ------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ------------------------------------------------------------------- The `^' and ~ forms and the two with `#' require EXTENDED_GLOB. The right hand side of an assignment is globbed in zsh. Unquoted assignments do file expansion after ':'s (intended for PATHs). `integer' does not allow -i; integers in bases other than 10 do not have "base#" prefixed to them when printed. Command execution: * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). $PATH is not searched for commands specified at invocation without -c. Aliases and functions: The order in which aliases and functions are defined is significant (function definitions with () expand aliases -- see question B3). Aliases and functions cannot be exported. There are no tracked aliases: command hashing replaces these. The use of aliases for key bindings is replaced by `bindkey'. Traps and signals: Traps and options are not local to functions; traps are not reset automatically when called; traps are called as functions themselves (this is a bug for the `trap "..." NAL' form of trap setting). TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). Editing: The options emacs, gmacs, trackall, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' become `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. `Trackall' is replaced by `hashcmds'. The `keyword' option does not exist and -k is instead interactivecomments. (`keyword' will not be in the next ksh release either.) Management of histories in multiple shells is different: the history list is not saved and restored after each command. \ does not escape editing chars (use ^V). Not all ksh bindings are set (e.g. `<ESC>#'; try <ESC>q). * # in an interactive shell is not treated as a comment by default. Built-in commands: Some built-ins (r, autoload, history, integer ...) were aliases in ksh. There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' `jobs' has no `-n' flag. `read' has no `-s' flag. In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' it is treated as an expression). Other idiosyncrasies: `select' always redisplays the list of selections on each loop. B2) Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in scripts/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: Logout, rehash, source, (un)limit built-in commands. *rc file for interactive shells. Directory stacks. Cshjunkie*, ignoreeof options. The CSH_NULL_GLOB option. >&, |& etc. redirection. foreach ... loops; alternative syntax for other loops. Alternative syntax `if ( ... ) ...' (also `for', `which'; this now requires the CSH_JUNKIE_PAREN option). $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... Escape sequences via % for prompts. Special array variables $PATH etc. are colon-separated, $path are arrays. !-type history (which may be turned off via `setopt nobanghist'). Arrays have csh-like features (see under B1)). B3) Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1. If the csh alias references "parameters" (\!:1 \!* etc.), then in zsh you need a function (referencing $1 $* etc.). Otherwise, you can use a zsh alias. 2. If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3. If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4. If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: a. convert all of them to zsh functions; or b. after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5. Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit is NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6. Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7. To begin a zsh alias with a - (dash, hyphen) character, use "alias --": csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8. Stay away from "alias -g" in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. B4) Similarities with tcsh: (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the scripts directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with bindkey -s (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. Bindkey -s allows limitless possibilities along these lines. B5) Similarities with bash Zsh has almost all the features that bash has (and much more); in addition it is about twice as fast, though this is less impressive than it sounds. With the new malloc by Sven Wischnowsky (only used if you used `configure --enable-zsh-mem' when configuring), zsh uses about the same amount of heap memory as bash, which was previously the biggest gripe. The only feature I am aware of that zsh doesn't have is setting a numerical value for ignoreeof --- it's always 10 --- but of course I don't use bash :-). However, zsh has no claims towards Posix compliancy and will not use GNU readline (zle is more powerful). In fact, bash is intended more as an enhanced sh than a ksh work-alike; it doesn't handle [[ ... ]], for example. B6) Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. rtfm.mit.edu:pub/usenet-by-group/news.answers/unix-faq/shell/csh-whynot if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers --- but note it is only slightly larger than bash and tcsh, and uses much less memory and CPU time than tcsh. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Section C: How to get various things to work C1) How do I turn off spelling correction for an individual command? You presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' C2) How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes *before* any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. C3) Why does my terminal act funny in way x? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that's_ not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: in 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. C4) Why does `$var' where var="foo bar" not do what I expect? In most Bourne-shell derivatives, multi-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of vble, args $vble produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=(\"$sentence\")" after which $words is an array with the words of $sentence, or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting), also the substitution ${=foo} to turn on word splitting on variable `foo'. Shwordsplit is set when zsh is invoked with the name `ksh'. C5) Why do my autoloaded functions not autoload [the first time]? When you put a shell function in an autoload directory (i.e. one mentioned in $FPATH), it should be written just as if it were a shell script. In other words, there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching '}' at the end. If you include those, then the first time you try to use the function, the _whole_ file is run --- in other words, zsh simply defines the function and does nothing else. As a concrete example, if you have a function which you would define on the command line as `xhead () { print -n "\033]2;$*\a"; }' and your have assigned `FPATH=~/fns', then your .zshrc should contain `autoload xhead' and the file ~/fns/xhead should contain only `print -n "\033]2;$*\a"'. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) The shell has just (version 2.6 beta 5) been enhanced to allow the Korn shell syntax, where the file contains the whole function including the definition lines. However, the form given above is unlikely to disappear as it allows significant benefits, including using a function directly as a script, and being able to link a function under different names. C6) How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is supported from version 2.6 onward). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$[ ... ]' method will always display in decimal. C7) How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. C9) Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. C10) How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. C11) Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. C12) Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (Nohup is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. Section D: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. D1) What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. Expansion is generally fairly intuitive and not under user control; for the rest of the section I will discuss completion only. D2) What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH and try to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see D4).) D3) How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via it's options. The default is for it to beep and completion to stop until you type another character. You can type ^D to see all the possible completions. This can be changed by the following options, among others (1) with nobeep set, that annoying beep goes away (2) with autolist set, when the completion is ambiguous you get a list without having to type ^D, (3) with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started (4) with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible. D4) How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example 'p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say 'p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, 'p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in D2)), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the -f before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): i) multiple square brackets after a single condition give alternatives: for example, 's[foo][bar]' says apply the completion if the word begins with `foo' or `bar', ii) spaces between conditions mean both must match: for example, 'p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', iii) commas between conditions mean either can match: for example, 'c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. D5) And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Section Z: The future of zsh Z1) What bugs are currently known and unfixed? Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question B1); note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. The `histlit' option adds newlines to lines in the history (and is broken in several other ways, e.g. !:x word selection; it may be removed). `time' is ignored with builtins and can't be used with {...} or (...); in shells with no job control the command name is blank. `set -x' (`setopt xtrace') still has a few glitches. The :q modifier doesn't split words and -q and -x don't work for variables. In vi mode, `u' can go past the original modification point. Autocd won't use globbed filenames. The singlelinezle option has problems with prompts containing escapes. Builtins at the end of a pipeline lose their status to previous commands (fixed from 2.6 beta8). The `r' command does not work inside $(...) or `...` expansions. Note that a few recent changes introduce incompatibilities (these are not bugs): An option CSH_JUNKIE_PAREN has proved necessary for the syntax `if ( <condition> ) <code>' and for similar `for' and `while' (but not `foreach') commands. This is because it is valid Bourne/Korn shell syntax to have a subshell command immediately after if, and the default syntax should be compliant with that. You also need CSH_JUNKIE_PAREN if you want to use the syntax `if [[ ... ]] command' (maybe with `command' being in the form `{ command1; ...}'; this was mainly here for csh compatibility. Remember you can use `[[ ... ]] && command' to do the same thing. Assignment of `...` and $(...) to variables in the form `foo=$(...)' is now always scalar; previously the command output was split and array assignment performed if more than one word resulted. You can still generate an array vie `foo=($(...))', which was always the safe way of doing it. Again, this is for Bourne/Korn compliance. The -h option to compctl has been removed (use `-k hosts' for the same effect); automatic handling of hosts after '@' has been removed (use e.g. `compctl -u -x "n[-1,@]" -k hosts -- finger'). Handling of backslashes in `echo' and `print' has changed. umask's behaviour with respect to symbolic operators has reversed (and is now ksh-compatible). The option CSH_JUNKIE_TILDE has been upgraded to GLOB_SUBST: instead of just ~'s and ='s, all characters become eligible for file expansion and globbing when the option is set. (The option was not present in 2.3 at all.) Z2) Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list (NOTE CHANGE OF ADDRESS), zsh-workers@math.gatech.edu so any suggestions, complaints, questions and matters for discussion should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at zsh@math.gatech.edu (his own e-mail address is coleman@math.gatech.edu). The list (everything since May 1992) is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. Z3) What's on the wish-list? Mostly, a lot of the code needs a major clean-up: particular offenders are the history code (hist.c: this is under way), parameter code (params.c) and substitution code (subst.c). A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. Ksh/sh compatibility could be improved; this is a useful long term goal. Option for glob qualifiers to follow perl syntax. Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. trap '...' FOO should be eval'd rather than called as a function. `PATH=' should clear the PATH: it inserts `.'; use `unset PATH' or `path=()' for the time being. This is not really a bug as the . would be used internally in any case (cf. ksh). Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document; thanks to Jim Mattson, Bas de Bakker and now Richard Coleman for their hard work as archivists, and to Peter Gray for maintaining the mailing list, without which zsh might easily have died, and to his successor, Rick Ohnemus. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wishnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.mal.com/zsh/". -- Peter Stephenson <P.Stephenson@swansea.ac.uk> Tel: +44 1792 205678 extn. 4461 WWW: http://python.swan.ac.uk/~pypeters/ Fax: +44 1792 295324 Department of Physics, University of Wales, Swansea, Singleton Park, Swansea, SA2 8PP, U.K. # Local Variables: # xref-1:(t 2931 49 0) # xref-2:(t 2982 26 1) # xref-3:(t 4839 15 2) # xref-4:(t 5713 23 3) # xref-5:(t 7153 33 4) # xref-6:(t 9053 30 5) # xref-7:(t 10131 22 6) # xref-8:(t 11209 63 7) # xref-9:(t 13331 40 8) # xref-10:(t 13523 31 9) # xref-11:(t 14482 20 10) # xref-12:(t 15004 6 11) # xref-13:(t 19217 25 12) # xref-14:(t 20377 35 13) # xref-15:(t 24102 38 14) # xref-16:(t 24632 27 15) # xref-17:(t 25561 26 16) # xref-18:(t 26349 47 17) # xref-19:(t 27683 45 18) # xref-20:(t 27730 68 19) # xref-21:(t 28178 50 20) # xref-22:(t 28914 44 21) # xref-23:(t 30652 61 22) # xref-24:(t 32663 65 23) # xref-25:(t 34103 34 24) # xref-26:(t 34750 40 25) # xref-27:(t 35108 40 26) # xref-28:(t 35576 76 27) # xref-29:(t 35925 44 28) # xref-30:(t 36843 71 29) # xref-31:(t 37218 64 30) # xref-32:(t 38043 39 31) # xref-33:(t 38420 23 32) # xref-34:(t 39321 42 33) # xref-35:(t 41570 49 34) # xref-36:(t 42487 54 35) # xref-37:(t 47268 53 36) # xref-38:(t 47986 29 37) # xref-39:(t 48017 46 38) # xref-40:(t 49358 17 39) # xref-41:(t 49412 16 40) # xref-42:(t 50952 65 41) # xref-43:(t 52363 28 42) # xref-44:(t 52731 28 43) # xref-45:(982 12 (6)) # xref-46:(1058 3 (41)) # xref-47:(1197 10 (6)) # xref-48:(1247 3 (1)) # xref-49:(1274 3 (2)) # xref-50:(1290 3 (8)) # xref-51:(1311 3 (8)) # xref-52:(1381 3 (8)) # xref-53:(1412 3 (6)) # xref-54:(1435 3 (7)) # xref-55:(1501 10 (8)) # xref-56:(1542 3 (9)) # xref-57:(1559 3 (12)) # xref-58:(1568 3 (13)) # xref-59:(1606 26 (14)) # xref-60:(1634 3 (15)) # xref-61:(1645 3 (16)) # xref-62:(1655 3 (25)) # xref-63:(1704 10 (18)) # xref-64:(1750 3 (19)) # xref-65:(1819 3 (20)) # xref-66:(1870 3 (21)) # xref-67:(1915 3 (22)) # xref-68:(1977 3 (23)) # xref-69:(2043 3 (24)) # xref-70:(2078 3 (26)) # xref-71:(2119 3 (27)) # xref-72:(2196 3 (28)) # xref-73:(2241 4 (29)) # xref-74:(2300 4 (29)) # xref-75:(2372 4 (41)) # xref-76:(2438 10 (31)) # xref-77:(2478 3 (32)) # xref-78:(2502 3 (33)) # xref-79:(2545 3 (34)) # xref-80:(2595 3 (35)) # xref-81:(2650 3 (36)) # xref-82:(2705 10 (37)) # xref-83:(2735 3 (38)) # xref-84:(2782 3 (41)) # xref-85:(2848 3 (43)) # xref-86:(4208 3 (6)) # xref-87:(4832 3 (41)) # xref-88:(5433 11 (41)) # xref-89:(7986 17 (41)) # xref-90:(8077 3 (6)) # xref-91:(9879 18 (39)) # xref-92:(14183 12 (22)) # xref-93:(14913 12 (22)) # xref-94:(17485 11 (13)) # xref-95:(20031 16 (40)) # xref-96:(20369 3 (11)) # xref-97:(41558 7 (35)) # xref-98:(48231 12 (10)) # End:
[note list of incompatibilities in Z1 which I've extended a bit. also changed `Frequently-Asked' to `Frequently Asked' because of what it says in the Oxford guide to English. still not convinced -- pws] Archive-Name: unix-faq/shell/zsh Last-Modified: 1996/04/25 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zsh.FAQ,v 2.12 1996/05/24 07:55:05 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996 (see end of document) Changes since last issue: - in A4: new beta version - in A5: new archive maintainer and site (and changed acknowledgments); changed lut archive address - in B1: correct typo **/foo~bar -> **/foo~*bar*; non-decimal integers now do have base# prefixed; note KSH_ARRAYS, GLOB_ASSIGN options. - in B2: note about >& and 2>&1. - in B5: mention bash doesn't currently have arrays :-). - in B6: turned csh-whynot location into URL & made it http. - in C4: mention IFS in article on splitting; correct `$var/$vble' typo. - new C13: how to list all history entries. - in Z1: note ~ to = change for references to directory stack; also vi keys for history search reversed; added to name of item; deleted bugs fixed in new version; added several new incompatibilities. - in Z2: coleman@math.gatech.edu This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. In fact, zsh is currently the most powerful freely available shell. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question A5); if you want to know what to do with insoluble problems, go to Z2). Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Section A: Introducing zsh and how to install it A0) Sources of information A1) What is it? A2) What is good at? A3) On what machines will it run? (Plus important compilation notes) A4) What's the latest version? A5) Where do I get it? A6) I don't have root access: how do I make zsh my login shell? Section B: How does zsh differ from...? B1) sh and ksh? B2) csh? B3) Why do my csh aliases not work? (Plus other alias pitfalls.) B4) tcsh? B5) bash? B6) Shouldn't zsh be more/less like ksh/(t)csh? Section C: How to get various things to work C1) How do I turn off spelling correction for an individual command? C2) How do I get the meta key to work on my xterm? C3) Why does my terminal act funny in some way? C4) Why does `$var' where var="foo bar" not do what I expect? C5) Why do my autoloaded functions not autoload [the first time]? C6) How does base arithmetic work? C7) How do I get a newline in my prompt? C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? C9) Why can't I bind \C-s and \C-q any more? C10) How do I execute command `foo' within function `foo'? C11) Why do history substitutions with single bangs do something funny? C12) Why does zsh kill off all my background jobs when I logout? C13) How do I list all my history entries? Section D: The mysteries of completion D1) What is completion? D2) What sorts of things can be completed? D3) How does zsh deal with ambiguous completions? D4) How do I get started with programmable completion? D5) And if programmable completion isn't good enough? Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Z2) Where do I report bugs, get more info / who's working on zsh? Z3) What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Section A: Introducing zsh and how to install it A0) Sources of information Information on zsh is now available via the World Wide Web. The URL is "http://www.mal.com/zsh/". The server provides this FAQ and much else (thanks to Mark Borges for this). The FAQ is at "http://www.mal.com/zsh/FAQ/". Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question A5). Note that if you are reading this file with GNU Emacs 19 and have my cross-referencing package xref.el (soon to be part of Emacs, but currently available from http://python.swan.ac.uk/~pypeters/comp/xref.html), you can pick up a version of this FAQ which is internally cross-referenced from: http://python.swan.ac.uk/~pypeters/comp/zsh.FAQ (As a lower-tech method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question Z2). A1) What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh), although it is not completely compatible. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question Z2). Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. A2) What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major feature in any other freely-available shell which zsh does not also have (except smallness). Command line editing: programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), multi-line commands editable as a single buffer (even files!), variable editing (vared), command buffer stack, print text straight into the buffer for immediate editing (print -z), execution of unbound commands, menu completion, variable, editing function and option name completion, inline expansion of variables, history commands. Globbing --- extremely powerful, including: recursive globbing (cf. find), file attribute qualifiers (size, type, etc. also cf. find), full alternation and negation of patterns. Handling of multiple redirections (simpler than tee). Large number of options for tailoring. Path expansion (=foo -> /usr/bin/foo). Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). Named directories. Comprehensive integer arithmetic. Manipulation of arrays (including reverse subscripting). Spelling correction. A3) On what machines will it run? Zsh was written for machines of the Berkeley UNIX family; most such machines (and all the most popular) will run it without major surgery. Modifications have been made so that it works under SYSVR4-based operating systems such as Solaris 2.x and OSF/1. The best thing is to suck it and see. Success has been obtained on older SYSVR3 systems, but you may need to modify the code. From version 2.6, the installation mechanism has been altered to use GNU Autoconf, which should make it easier to recognise new machine types. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in to configure zsh automatically, then send the required context diffs to the list (see question Z2). To get it to work, retrieve the source distribution (see question A5), un-gzip it, un-tar it and read the INSTALL file in the top directory. Here are a couple of known installation problems at present. *Note for Solaris 2.2 and 2.3*: The UCB versions of the routines for reading directories are not usable (the struct definitions are incompatible with the ones assumed by zsh). The symptom of this is that globbed filenames in the compiled version of zsh will be missing the first two letters. To avoid this, make sure you compile zsh without any reference to /usr/ucblib in (e.g.) your LD_LIBRARY_PATH. *Note for OSF/1 3.0*: There is apparently a bug in the header file /usr/include/rpcsvc/ypclnt.h; the prototype for yp_all() has a struct ypall_callback as its final argument, which should be a pointer (struct ypall_callback *). This prevents compilation of zle_tricky.c. If you can't modify the header file, make a subdirectory called rpcsvc, copy ypclnt.h there, modify that copy, and put a `-I.' argument into CFLAGS in Makefile for the Src subdirectory when compiling. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. A4) What's the latest version? Zsh 2.5.0 was the last major release: the final form is 2.5.03. Many bugs were fixed after 2.3.1, which was the previous major release, and there were many new features, notably programmable completion. This version is known to have a bug with pipelines inside other shell structures (now fixed in 2.6). Work has now started on 2.6 and 2.6-beta17 is available; note that even numbered minor versions are not released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question Z1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives. A5) Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.cso.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ fpt://ftp.uni-trier.de/pub/unix/shell/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Australia ftp://ftp.ips.oz.au/pub/packages/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh-hzoli/ (If you don't understand URL's, the first thing after the ftp:// is the hostname and the remainder after the / is the directory. You can supply these directly to a Web browser. If you're reading this with a recent version of Netscape Navigator, you may just have to click on them.) The latest full release is in zsh.tar.gz in these directories. Note that this is in gzip format: you will need GNU gzip from your nearest GNU archive to unpack it. The up-to-the-minute development version is in zsh-beta.tar.gz. There is also a version under RCS control which may be more suitable for source hackers. A6) I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the -l tells zsh it is a login shell). It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as '-zsh', you can link zsh to -zsh (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure -zsh is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Section B: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. B1) Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh. Various options can be turned on which will increase ksh compatibility, though decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_OPTION_PRINT, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, SH_WORD_SPLIT (see question C4) and SINGLE_LINE_ZLE. Of these, SH_WORD_SPLIT and NO_NOMATCH are the most likely to spoil your ksh scripts if unset. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh'. Capitalised words with underlines refer to shell options. Syntax: * Shell word splitting: see question C4). (This is particularly frequently asked about; use SH_WORD_SPLIT.) * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is available from version 2.6-beta17; note even in this case $array[2] with no braces refers to element 2 of $array, etc. Coprocesses are established by `coproc'; `|&' behaves like csh. Opening for both input and output via <> is not yet supported. (This syntax does numeric globbing.) Command line substitutions, globbing etc.: * Failure to match a globbing pattern causes an error (use NO_NOMATCH). * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but * in zsh. (GLOB_SUBST has just been added to fix this.) On the other hand, `foo=*' does globbing immediately on the right hand side of the assignment (this has changed from 2.6-beta17; the old behaviour now requires the option GLOB_ASSIGN). The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) The $((...)) version of numeric evaluation was not available before version 2.6 (use $[...]). $PSn do not do parameter substitution by default (use PROMPT_SUBST: this still needs some fixing for complex substitutions). Globbing does not allow ksh-style `pattern-lists'. Equivalents: ------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ------------------------------------------------------------------- The `^' and ~ forms and the two with `#' require EXTENDED_GLOB. [1] Note that ~ is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the ~ operator). As the `**' operator cannot be grouped (inside parentheses it is treated as *), this is the way to exclude some subdirectories from matching a `**'. The right hand side of an assignment is globbed in zsh. Unquoted assignments do file expansion after `:'s (intended for PATHs). `integer' does not allow -i. Command execution: * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). $PATH is not searched for commands specified at invocation without -c. Aliases and functions: The order in which aliases and functions are defined is significant (function definitions with () expand aliases -- see question B3). Aliases and functions cannot be exported. There are no tracked aliases: command hashing replaces these. The use of aliases for key bindings is replaced by `bindkey'. Traps and signals: Traps and options are not local to functions; traps are not reset automatically when called; traps are called as functions themselves (this is a bug for the `trap "..." NAL' form of trap setting). TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). Editing: The options emacs, gmacs, trackall, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' become `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. `Trackall' is replaced by `hashcmds'. The `keyword' option does not exist and -k is instead interactivecomments. (`keyword' will not be in the next ksh release either.) Management of histories in multiple shells is different: the history list is not saved and restored after each command. \ does not escape editing chars (use ^V). Not all ksh bindings are set (e.g. `<ESC>#'; try <ESC>q). * # in an interactive shell is not treated as a comment by default. Built-in commands: Some built-ins (r, autoload, history, integer ...) were aliases in ksh. There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' `jobs' has no `-n' flag. `read' has no `-s' flag. In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' it is treated as an expression). Other idiosyncrasies: `select' always redisplays the list of selections on each loop. B2) Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in scripts/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: Logout, rehash, source, (un)limit built-in commands. *rc file for interactive shells. Directory stacks. Cshjunkie*, ignoreeof options. The CSH_NULL_GLOB option. >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'. If you define a function incorporating the latter, then look at it with the `functions' command or `which', you will see it has been converted to the former.) foreach ... loops; alternative syntax for other loops. Alternative syntax `if ( ... ) ...' (also `for', `which'; this now requires the CSH_JUNKIE_PAREN option). $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... Escape sequences via % for prompts. Special array variables $PATH etc. are colon-separated, $path are arrays. !-type history (which may be turned off via `setopt nobanghist'). Arrays have csh-like features (see under B1)). B3) Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1. If the csh alias references "parameters" (\!:1 \!* etc.), then in zsh you need a function (referencing $1 $* etc.). Otherwise, you can use a zsh alias. 2. If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3. If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4. If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: a. convert all of them to zsh functions; or b. after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5. Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit is NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6. Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7. To begin a zsh alias with a - (dash, hyphen) character, use "alias --": csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8. Stay away from "alias -g" in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. B4) Similarities with tcsh: (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the scripts directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with bindkey -s (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. Bindkey -s allows limitless possibilities along these lines. B5) Similarities with bash Zsh has almost all the features that bash has (and much more); in addition it is about twice as fast, though this is less impressive than it sounds. With the new malloc by Sven Wischnowsky (only used if you used `configure --enable-zsh-mem' when configuring), zsh uses about the same amount of heap memory as bash, which was previously the biggest gripe. The only feature I am aware of that zsh doesn't have is setting a numerical value for ignoreeof --- it's always 10 --- but of course I don't use bash :-). On the other hand, zsh has no claims towards Posix compliancy and will not use GNU readline (zle is more powerful). In fact, bash is intended more as an enhanced sh than a ksh work-alike; it doesn't handle [[ ... ]], or (yet) arrays, for example. Of course, they're working on bash, too. Some zsh-like features are suggested for future versions. B6) Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/shell/\ csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers --- but note it is only slightly larger than bash and tcsh, and uses much less memory and CPU time than tcsh. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Section C: How to get various things to work C1) How do I turn off spelling correction for an individual command? You presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' C2) How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes *before* any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. C3) Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that's_ not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: in 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. C4) Why does `$var' where var="foo bar" not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=: foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=(\"$sentence\")" after which $words is an array with the words of $sentence, or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh'. C5) Why do my autoloaded functions not autoload [the first time]? When you put a shell function in an autoload directory (i.e. one mentioned in $FPATH), it should be written just as if it were a shell script. In other words, there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching '}' at the end. If you include those, then the first time you try to use the function, the _whole_ file is run --- in other words, zsh simply defines the function and does nothing else. As a concrete example, if you have a function which you would define on the command line as `xhead () { print -n "\033]2;$*\a"; }' and your have assigned `FPATH=~/fns', then your .zshrc should contain `autoload xhead' and the file ~/fns/xhead should contain only `print -n "\033]2;$*\a"'. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) The shell has just (version 2.6 beta 5) been enhanced to allow the Korn shell syntax, where the file contains the whole function including the definition lines. However, the form given above is unlikely to disappear as it allows significant benefits, including using a function directly as a script, and being able to link a function under different names. C6) How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is supported from version 2.6 onward). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$[ ... ]' method will always display in decimal. C7) How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. C9) Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. C10) How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. C11) Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. C12) Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (Nohup is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. C13) How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. Section D: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. D1) What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. Expansion is generally fairly intuitive and not under user control; for the rest of the section I will discuss completion only. D2) What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH and try to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see D4).) D3) How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via it's options. The default is for it to beep and completion to stop until you type another character. You can type ^D to see all the possible completions. This can be changed by the following options, among others (1) with nobeep set, that annoying beep goes away (2) with autolist set, when the completion is ambiguous you get a list without having to type ^D, (3) with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started (4) with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible. D4) How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example 'p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say 'p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, 'p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in D2)), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the -f before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): i) multiple square brackets after a single condition give alternatives: for example, 's[foo][bar]' says apply the completion if the word begins with `foo' or `bar', ii) spaces between conditions mean both must match: for example, 'p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', iii) commas between conditions mean either can match: for example, 'c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. D5) And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question B1); note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. `time' is ignored with builtins and can't be used with {...}. `set -x' (`setopt xtrace') still has a few glitches. The :q modifier doesn't split words and -q and -x don't work for variables. In vi mode, `u' can go past the original modification point. Autocd won't use globbed filenames. The singlelinezle option has problems with prompts containing escapes. The `r' command does not work inside $(...) or `...` expansions. Note that a few recent changes introduce incompatibilities (these are not bugs): The current beta version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. The keys for forward/reverse search in vi mode, / and ?, have been reversed: the intention is to provide vi rather than ksh compatibility. The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. The `HISTCHARS' variable is now `histchars'. An option CSH_JUNKIE_PAREN has proved necessary for the syntax `if ( <condition> ) <code>' and for similar `for' and `while' (but not `foreach') commands. This is because it is valid Bourne/Korn shell syntax to have a subshell command immediately after if, and the default syntax should be compliant with that. You also need CSH_JUNKIE_PAREN if you want to use the syntax `if [[ ... ]] command' (maybe with `command' being in the form `{ command1; ...}'; this was mainly here for csh compatibility. Remember you can use `[[ ... ]] && command' to do the same thing. Assignment of `...` and $(...) to variables in the form `foo=$(...)' is now always scalar; previously the command output was split and array assignment performed if more than one word resulted. You can still generate an array vie `foo=($(...))', which was always the safe way of doing it. Again, this is for Bourne/Korn compliance. (Note the same is true for globbing, as mentioned in B1) above.) The -h option to compctl has been removed (use `-k hosts' for the same effect); automatic handling of hosts after '@' has been removed (use e.g. `compctl -u -x "n[-1,@]" -k hosts -- finger'). Handling of backslashes in `echo' and `print' has changed. umask's behaviour with respect to symbolic operators has reversed (and is now ksh-compatible). The option CSH_JUNKIE_TILDE has been upgraded to GLOB_SUBST: instead of just ~'s and ='s, all characters become eligible for file expansion and globbing when the option is set. (The option was not present in 2.3 at all.) The corresponding one-time switch ${~...}, together with ${^.,.} and ${=...}, now force the corresponding options on for the evaluation, rather than toggling (double the character to force off). "${#foo}" (with the quotes) now gives an array length if `foo' is an array. ("${(c)#foo}" gives the total character length.) The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) Z2) Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so any suggestions, complaints, questions and matters for discussion should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at comeman@math.gatech.edu The list (everything since May 1992) is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. A useful World Wide Web interface to recent mailings is currently kept at http://www-stud.enst.fr/~tardieu/mailarchive/zsh-list/index.html by Samuel Tardieu. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. Z3) What's on the wish-list? Mostly, a lot of the code needs a major clean-up: particular offenders are the history code (hist.c: this is under way), parameter code (params.c) and substitution code (subst.c). A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. Ksh/sh compatibility could be improved; this is a useful long term goal. Option for glob qualifiers to follow perl syntax. Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. trap '...' FOO should be eval'd rather than called as a function. `PATH=' should clear the PATH: it inserts `.'; use `unset PATH' or `path=()' for the time being. This is not really a bug as the . would be used internally in any case (cf. ksh). Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wishnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.mal.com/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1996/06/25 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zsh.FAQ,v 2.14 1996/06/25 07:41:33 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996 (see end of document) Changes since last issue: - in A4: new beta version - in A5: updated archive list - in A6: extended 'exec zsh' for login files from Bart Schaefer - in B1: added more prominent note on word splitting; other entries updated - in C1: mention globbing - in Z1: <> now does redirection, not numeric globbing. *NB!*, exec, noglob etc. behaviour changed This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. In fact, zsh is currently the most powerful freely available shell. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question A5); if you want to know what to do with insoluble problems, go to Z2). Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Section A: Introducing zsh and how to install it A0) Sources of information A1) What is it? A2) What is good at? A3) On what machines will it run? (Plus important compilation notes) A4) What's the latest version? A5) Where do I get it? A6) I don't have root access: how do I make zsh my login shell? Section B: How does zsh differ from...? B1) sh and ksh? B2) csh? B3) Why do my csh aliases not work? (Plus other alias pitfalls.) B4) tcsh? B5) bash? B6) Shouldn't zsh be more/less like ksh/(t)csh? Section C: How to get various things to work C1) How do I turn off spelling correction/globbing for an individual command? C2) How do I get the meta key to work on my xterm? C3) Why does my terminal act funny in some way? C4) Why does `$var' where var="foo bar" not do what I expect? C5) Why do my autoloaded functions not autoload [the first time]? C6) How does base arithmetic work? C7) How do I get a newline in my prompt? C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? C9) Why can't I bind \C-s and \C-q any more? C10) How do I execute command `foo' within function `foo'? C11) Why do history substitutions with single bangs do something funny? C12) Why does zsh kill off all my background jobs when I logout? C13) How do I list all my history entries? Section D: The mysteries of completion D1) What is completion? D2) What sorts of things can be completed? D3) How does zsh deal with ambiguous completions? D4) How do I get started with programmable completion? D5) And if programmable completion isn't good enough? Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Z2) Where do I report bugs, get more info / who's working on zsh? Z3) What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Section A: Introducing zsh and how to install it A0) Sources of information Information on zsh is now available via the World Wide Web. The URL is "http://www.mal.com/zsh/". The server provides this FAQ and much else (thanks to Mark Borges for this). The FAQ is at "http://www.mal.com/zsh/FAQ/". Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question A5). Note that if you are reading this file with GNU Emacs 19 and have my cross-referencing package xref.el (soon to be part of Emacs, but currently available from http://python.swan.ac.uk/~pypeters/comp/xref.html), you can pick up a version of this FAQ which is internally cross-referenced from: http://python.swan.ac.uk/~pypeters/comp/zsh.FAQ (As a lower-tech method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question Z2). A1) What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh), although it is not completely compatible. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question Z2). Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. A2) What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major feature in any other freely-available shell which zsh does not also have (except smallness). Command line editing: programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), multi-line commands editable as a single buffer (even files!), variable editing (vared), command buffer stack, print text straight into the buffer for immediate editing (print -z), execution of unbound commands, menu completion, variable, editing function and option name completion, inline expansion of variables, history commands. Globbing --- extremely powerful, including: recursive globbing (cf. find), file attribute qualifiers (size, type, etc. also cf. find), full alternation and negation of patterns. Handling of multiple redirections (simpler than tee). Large number of options for tailoring. Path expansion (=foo -> /usr/bin/foo). Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). Named directories. Comprehensive integer arithmetic. Manipulation of arrays (including reverse subscripting). Spelling correction. A3) On what machines will it run? Zsh was written for machines of the Berkeley UNIX family; most such machines (and all the most popular) will run it without major surgery. Modifications have been made so that it works under SYSVR4-based operating systems such as Solaris 2.x and OSF/1. The best thing is to suck it and see. Success has been obtained on older SYSVR3 systems, but you may need to modify the code. From version 2.6, the installation mechanism has been altered to use GNU Autoconf, which should make it easier to recognise new machine types. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in to configure zsh automatically, then send the required context diffs to the list (see question Z2). To get it to work, retrieve the source distribution (see question A5), un-gzip it, un-tar it and read the INSTALL file in the top directory. Here are a couple of known installation problems at present. *Note for Solaris 2.2 and 2.3*: The UCB versions of the routines for reading directories are not usable (the struct definitions are incompatible with the ones assumed by zsh). The symptom of this is that globbed filenames in the compiled version of zsh will be missing the first two letters. To avoid this, make sure you compile zsh without any reference to /usr/ucblib in (e.g.) your LD_LIBRARY_PATH. *Note for OSF/1 3.0*: There is apparently a bug in the header file /usr/include/rpcsvc/ypclnt.h; the prototype for yp_all() has a struct ypall_callback as its final argument, which should be a pointer (struct ypall_callback *). This prevents compilation of zle_tricky.c. If you can't modify the header file, make a subdirectory called rpcsvc, copy ypclnt.h there, modify that copy, and put a `-I.' argument into CFLAGS in Makefile for the Src subdirectory when compiling. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. A4) What's the latest version? Zsh 2.5.0 was the last major release: the final form is 2.5.03. Many bugs were fixed after 2.3.1, which was the previous major release, and there were many new features, notably programmable completion. This version is known to have a bug with pipelines inside other shell structures (now fixed in 2.6). Work has now started on 2.6 and 2.6-beta21 is available; note that even numbered minor versions are not released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question Z1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives. A5) Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ Australia ftp://ftp.ips.oz.au/pub/packages/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ ftp://ftp.prz.tu-berlin.de/pub/unix/shells/zsh Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.iij.ad.jp/pub/misc/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.cso.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ (If you don't understand URL's, the first thing after the ftp:// is the hostname and the remainder after the / is the directory. You can supply these directly to a Web browser. If you're reading this with a recent version of Netscape Navigator, you may just have to click on them.) The latest full release is in zsh.tar.gz in these directories. Note that this is in gzip format: you will need GNU gzip from your nearest GNU archive to unpack it. The up-to-the-minute development version is in zsh-beta.tar.gz. There is also a version under RCS control which may be more suitable for source hackers. A6) I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the -l tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as '-zsh', you can link zsh to -zsh (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure -zsh is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Section B: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. B1) Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh. The classic difference is word splitting, discussed in C4); this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAY, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, SH_WORD_SPLIT (see question C4) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh'; those marked - have recently (i.e., between the release and the beta version) become ksh-compatible. Capitalised words with underlines refer to shell options. Syntax: * Shell word splitting: see question C4). * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is available from version 2.6-beta17; note even in this case $array[2] with no braces refers to element 2 of $array, etc. Coprocesses are established by `coproc'; `|&' behaves like csh. - Opening for both input and output via <> is only available from 2.6-beta21; before it performed globbing of any sequence of decimal digits. For the latter, you now need <->. Command line substitutions, globbing etc.: * Failure to match a globbing pattern causes an error (use NO_NOMATCH). * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but * in zsh. (GLOB_SUBST has just been added to fix this.) - On the other hand, `foo=*' does globbing immediately on the right hand side of the assignment (this has changed from 2.6-beta17; the old behaviour now requires the option GLOB_ASSIGN). The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) * $PSn do not do parameter substitution by default (use PROMPT_SUBST). Globbing does not allow ksh-style `pattern-lists'. Equivalents: ------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that ~ is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the ~ operator). As the `**' operator cannot be grouped (inside parentheses it is treated as *), this is the way to exclude some subdirectories from matching a `**'. Unquoted assignments do file expansion after `:'s (intended for PATHs). `integer' does not allow -i. Command execution: * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). $PATH is not searched for commands specified at invocation without -c. Aliases and functions: The order in which aliases and functions are defined is significant (function definitions with () expand aliases -- see question B3). Aliases and functions cannot be exported. There are no tracked aliases: command hashing replaces these. The use of aliases for key bindings is replaced by `bindkey'. * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). Traps and signals: Traps are not local to functions, are not reset automatically when called, and are called as functions themselves (this is a bug for the `trap "..." NAL' form of trap setting). TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). Editing: The options emacs, gmacs, trackall, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' become `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. `Trackall' is replaced by `hashcmds'. The `keyword' option does not exist and -k is instead interactivecomments. (`keyword' will not be in the next ksh release either.) Management of histories in multiple shells is different: the history list is not saved and restored after each command. \ does not escape editing chars (use ^V). Not all ksh bindings are set (e.g. `<ESC>#'; try <ESC>q). * # in an interactive shell is not treated as a comment by default. Built-in commands: Some built-ins (r, autoload, history, integer ...) were aliases in ksh. There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' `jobs' has no `-n' flag. `read' has no `-s' flag. In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' it is treated as an expression). Other idiosyncrasies: `select' always redisplays the list of selections on each loop. B2) Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in scripts/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: Logout, rehash, source, (un)limit built-in commands. *rc file for interactive shells. Directory stacks. Cshjunkie*, ignoreeof options. The CSH_NULL_GLOB option. >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) foreach ... loops; alternative syntax for other loops. Alternative syntax `if ( ... ) ...' (also `for', `which'; this now requires the CSH_JUNKIE_PAREN option). $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... Escape sequences via % for prompts. Special array variables $PATH etc. are colon-separated, $path are arrays. !-type history (which may be turned off via `setopt nobanghist'). Arrays have csh-like features (see under B1)). B3) Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1. If the csh alias references "parameters" (\!:1 \!* etc.), then in zsh you need a function (referencing $1 $* etc.). Otherwise, you can use a zsh alias. 2. If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3. If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4. If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: a. convert all of them to zsh functions; or b. after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5. Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6. Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7. To begin a zsh alias with a - (dash, hyphen) character, use "alias --": csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8. Stay away from "alias -g" in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. B4) Similarities with tcsh: (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the scripts directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with bindkey -s (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. Bindkey -s allows limitless possibilities along these lines. B5) Similarities with bash Zsh has almost all the features that bash has (and much more); in addition it is about twice as fast, though this is less impressive than it sounds. With the new malloc by Sven Wischnowsky (only used if you used `configure --enable-zsh-mem' when configuring), zsh uses about the same amount of heap memory as bash, which was previously the biggest gripe. The only feature I am aware of that zsh doesn't have is setting a numerical value for ignoreeof --- it's always 10 --- but of course I don't use bash :-). On the other hand, zsh has no claims towards Posix compliancy and will not use GNU readline (zle is more powerful). In fact, bash is intended more as an enhanced sh than a ksh work-alike; it doesn't handle [[ ... ]], or (yet) arrays, for example. Of course, they're working on bash, too. Some zsh-like features are suggested for future versions. B6) Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/shell/\ csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers --- but note it is only slightly larger than bash and tcsh, and uses much less memory and CPU time than tcsh. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Section C: How to get various things to work C1) How do I turn off spelling correction/globbing for an individual command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' (you can have both nocorrect and nglob, if you like). C2) How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes *before* any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. C3) Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that's_ not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: in 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. C4) Why does `$var' where var="foo bar" not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=(\"$sentence\")" after which $words is an array with the words of $sentence, or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh'. C5) Why do my autoloaded functions not autoload [the first time]? When you put a shell function in an autoload directory (i.e. one mentioned in $FPATH), it should be written just as if it were a shell script. In other words, there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching '}' at the end. If you include those, then the first time you try to use the function, the _whole_ file is run --- in other words, zsh simply defines the function and does nothing else. As a concrete example, if you have a function which you would define on the command line as `xhead () { print -n "\033]2;$*\a"; }' and your have assigned `FPATH=~/fns', then your .zshrc should contain `autoload xhead' and the file ~/fns/xhead should contain only `print -n "\033]2;$*\a"'. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) The shell has just (version 2.6 beta 5) been enhanced to allow the Korn shell syntax, where the file contains the whole function including the definition lines. However, the form given above is unlikely to disappear as it allows significant benefits, including using a function directly as a script, and being able to link a function under different names. C6) How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is supported from version 2.6 onward). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$[ ... ]' method will always display in decimal. C7) How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. C9) Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. C10) How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. C11) Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. C12) Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (Nohup is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. C13) How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. Section D: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. D1) What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. Expansion is generally fairly intuitive and not under user control; for the rest of the section I will discuss completion only. D2) What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH and try to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see D4).) D3) How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via it's options. The default is for it to beep and completion to stop until you type another character. You can type ^D to see all the possible completions. This can be changed by the following options, among others (1) with nobeep set, that annoying beep goes away (2) with autolist set, when the completion is ambiguous you get a list without having to type ^D, (3) with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started (4) with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible. D4) How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example 'p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say 'p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, 'p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in D2)), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the -f before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): i) multiple square brackets after a single condition give alternatives: for example, 's[foo][bar]' says apply the completion if the word begins with `foo' or `bar', ii) spaces between conditions mean both must match: for example, 'p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', iii) commas between conditions mean either can match: for example, 'c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. D5) And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question B1); note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. `time' is ignored with builtins and can't be used with {...}. `set -x' (`setopt xtrace') still has a few glitches. The :q modifier doesn't split words and -q and -x don't work for variables. In vi mode, `u' can go past the original modification point. The singlelinezle option has problems with prompts containing escapes. The `r' command does not work inside $(...) or `...` expansions. Note that a few recent changes introduce incompatibilities (these are not bugs): From 2.6.beta21, <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. From 2.6.beta20, the command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). The current beta version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. The keys for forward/reverse search in vi mode, / and ?, have been reversed: the intention is to provide vi rather than ksh compatibility. (This change still appears to be controversial.) The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. The `HISTCHARS' variable is now `histchars'. Currently both are tied together for compatibility. An option CSH_JUNKIE_PAREN has proved necessary for the syntax `if ( <condition> ) <code>' and for similar `for' and `while' (but not `foreach') commands. This is because it is valid Bourne/Korn shell syntax to have a subshell command immediately after if, and the default syntax should be compliant with that. You also need CSH_JUNKIE_PAREN if you want to use the syntax `if [[ ... ]] command' (maybe with `command' being in the form `{ command1; ...}'; this was mainly here for csh compatibility. Remember you can use `[[ ... ]] && command' to do the same thing. Assignment of `...` and $(...) to variables in the form `foo=$(...)' is now always scalar; previously the command output was split and array assignment performed if more than one word resulted. You can still generate an array vie `foo=($(...))', which was always the safe way of doing it. Again, this is for Bourne/Korn compliance. (Note the same is true for globbing, as mentioned in B1) above.) The -h option to compctl has been removed (use `-k hosts' for the same effect); automatic handling of hosts after '@' has been removed (use e.g. `compctl -u -x "n[-1,@]" -k hosts -- finger'). Handling of backslashes in `echo' and `print' has changed. umask's behaviour with respect to symbolic operators has reversed (and is now ksh-compatible). The option CSH_JUNKIE_TILDE has been upgraded to GLOB_SUBST: instead of just ~'s and ='s, all characters become eligible for file expansion and globbing when the option is set. (The option was not present in 2.3 at all.) The corresponding one-time switch ${~...}, together with ${^.,.} and ${=...}, now force the corresponding options on for the evaluation, rather than toggling (double the character to force off). "${#foo}" (with the quotes) now gives an array length if `foo' is an array. ("${(c)#foo}" gives the total character length.) The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) Z2) Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so any suggestions, complaints, questions and matters for discussion should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at comeman@math.gatech.edu The list (everything since May 1992) is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. A useful World Wide Web interface to recent mailings is currently kept at http://www-stud.enst.fr/~tardieu/mailarchive/zsh-list/index.html by Samuel Tardieu. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. Z3) What's on the wish-list? Mostly, a lot of the code needs a major clean-up: particular offenders are the history code (hist.c: this is under way), parameter code (params.c) and substitution code (subst.c). A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. Ksh/sh compatibility could be improved; this is a useful long term goal. Option for glob qualifiers to follow perl syntax. Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. trap '...' FOO should be eval'd rather than called as a function. `PATH=' should clear the PATH: it inserts `.'; use `unset PATH' or `path=()' for the time being. This is not really a bug as the . would be used internally in any case (cf. ksh). Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wishnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.mal.com/zsh/". # Local Variables: # xref-1:(t 3244 49 0) # xref-2:(t 3295 26 1) # xref-3:(t 5151 15 2) # xref-4:(t 6024 23 3) # xref-5:(t 7481 33 4) # xref-6:(t 9741 29 5) # xref-7:(t 10818 22 6) # xref-8:(t 12535 63 7) # xref-9:(t 15186 40 8) # xref-10:(t 15377 31 9) # xref-11:(t 16644 20 10) # xref-12:(t 17198 6 11) # xref-13:(t 18183 21 12) # xref-14:(t 19427 1 13) # xref-15:(t 19520 12 14) # xref-16:(t 22216 25 15) # xref-17:(t 22899 10 16) # xref-18:(t 23470 35 17) # xref-19:(t 27255 38 18) # xref-20:(t 27785 27 19) # xref-21:(t 28721 26 20) # xref-22:(t 29504 15 21) # xref-23:(t 29641 47 22) # xref-24:(t 30993 45 23) # xref-25:(t 31040 77 24) # xref-26:(t 31657 50 25) # xref-27:(t 32407 47 26) # xref-28:(t 34169 61 27) # xref-29:(t 36595 65 28) # xref-30:(t 38035 34 29) # xref-31:(t 38702 40 30) # xref-32:(t 39068 40 31) # xref-33:(t 39547 76 32) # xref-34:(t 39896 44 33) # xref-35:(t 40465 58 34) # xref-36:(t 40814 71 35) # xref-37:(t 41189 64 36) # xref-38:(t 42014 42 37) # xref-39:(t 42189 39 38) # xref-40:(t 42566 23 39) # xref-41:(t 43467 42 40) # xref-42:(t 45744 49 41) # xref-43:(t 46661 54 42) # xref-44:(t 51610 53 43) # xref-45:(t 52328 29 44) # xref-46:(t 52359 78 45) # xref-47:(t 53369 17 46) # xref-48:(t 54710 16 47) # xref-49:(t 56807 65 48) # xref-50:(t 58231 39 49) # xref-51:(t 58734 28 50) # xref-52:(369 2 (8)) # xref-53:(395 2 (6)) # xref-54:(425 2 (7)) # xref-55:(489 2 (9)) # xref-56:(565 2 (24)) # xref-57:(591 2 (45)) # xref-58:(1211 12 (6)) # xref-59:(1287 3 (48)) # xref-60:(1426 10 (6)) # xref-61:(1476 3 (1)) # xref-62:(1503 3 (2)) # xref-63:(1519 3 (8)) # xref-64:(1540 3 (8)) # xref-65:(1610 3 (8)) # xref-66:(1641 3 (6)) # xref-67:(1664 3 (7)) # xref-68:(1729 10 (8)) # xref-69:(1770 3 (9)) # xref-70:(1786 3 (15)) # xref-71:(1795 3 (48)) # xref-72:(1833 26 (18)) # xref-73:(1861 3 (19)) # xref-74:(1871 3 (20)) # xref-75:(1881 3 (22)) # xref-76:(1930 10 (23)) # xref-77:(1976 3 (24)) # xref-78:(2054 3 (25)) # xref-79:(2105 3 (26)) # xref-80:(2153 3 (27)) # xref-81:(2215 3 (28)) # xref-82:(2281 3 (29)) # xref-83:(2316 3 (31)) # xref-84:(2357 3 (32)) # xref-85:(2434 3 (33)) # xref-86:(2479 4 (34)) # xref-87:(2538 4 (35)) # xref-88:(2610 4 (36)) # xref-89:(2675 4 (37)) # xref-90:(2719 10 (38)) # xref-91:(2759 3 (39)) # xref-92:(2783 3 (40)) # xref-93:(2826 3 (41)) # xref-94:(2876 3 (42)) # xref-95:(2931 3 (43)) # xref-96:(2986 10 (44)) # xref-97:(3016 3 (45)) # xref-98:(3095 3 (48)) # xref-99:(3161 3 (50)) # xref-100:(4521 3 (6)) # xref-101:(5144 3 (48)) # xref-102:(5745 11 (48)) # xref-103:(8303 15 (48)) # xref-104:(8392 3 (6)) # xref-105:(10566 18 (46)) # xref-106:(15715 3 (27)) # xref-107:(16445 12 (27)) # xref-108:(17180 12 (27)) # xref-109:(20325 12 (48)) # xref-110:(23124 16 (47)) # xref-111:(23462 3 (11)) # xref-112:(45732 7 (42)) # xref-113:(52605 12 (10)) # xref-114:(55707 13 (12)) # End:
Archive-Name: unix-faq/shell/zsh Last-Modified: 1996/07/25 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zsh.FAQ,v 2.16 1996/07/25 08:08:47 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996 (see end of document) Changes since last issue: - in A3: updated configuration information; deleted some machine- specific information more useful contained in Etc/MACHINES; referred to that. - in A4: new version; note coming 3.0 release. - in B1: mention `emulate' command to emulate ksh. - in C7: another way of getting a newline into a prompt. - in D1: mention ^xg. Other minor wording changes in section D. - in Z1: most recent shell changes (mainly for POSIX), mention quoting in prompts, separate 2.5 and 3.0 changes. This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. In fact, zsh is currently the most powerful freely available shell. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question A5); if you want to know what to do with insoluble problems, go to Z2). Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Section A: Introducing zsh and how to install it A0) Sources of information A1) What is it? A2) What is good at? A3) On what machines will it run? (Plus important compilation notes) A4) What's the latest version? A5) Where do I get it? A6) I don't have root access: how do I make zsh my login shell? Section B: How does zsh differ from...? B1) sh and ksh? B2) csh? B3) Why do my csh aliases not work? (Plus other alias pitfalls.) B4) tcsh? B5) bash? B6) Shouldn't zsh be more/less like ksh/(t)csh? Section C: How to get various things to work C1) How do I turn off spelling correction/globbing for an individual command? C2) How do I get the meta key to work on my xterm? C3) Why does my terminal act funny in some way? C4) Why does `$var' where var="foo bar" not do what I expect? C5) Why do my autoloaded functions not autoload [the first time]? C6) How does base arithmetic work? C7) How do I get a newline in my prompt? C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? C9) Why can't I bind \C-s and \C-q any more? C10) How do I execute command `foo' within function `foo'? C11) Why do history substitutions with single bangs do something funny? C12) Why does zsh kill off all my background jobs when I logout? C13) How do I list all my history entries? Section D: The mysteries of completion D1) What is completion? D2) What sorts of things can be completed? D3) How does zsh deal with ambiguous completions? D4) How do I get started with programmable completion? D5) And if programmable completion isn't good enough? Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Z2) Where do I report bugs, get more info / who's working on zsh? Z3) What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Section A: Introducing zsh and how to install it A0) Sources of information Information on zsh is now available via the World Wide Web. The URL is "http://www.mal.com/zsh/". The server provides this FAQ and much else (thanks to Mark Borges for this). The FAQ is at "http://www.mal.com/zsh/FAQ/". Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question A5). (As a lower-tech method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question Z2). A1) What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh), although it is not completely compatible. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question Z2). Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. A2) What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major feature in any other freely-available shell which zsh does not also have (except smallness). Command line editing: programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), multi-line commands editable as a single buffer (even files!), variable editing (vared), command buffer stack, print text straight into the buffer for immediate editing (print -z), execution of unbound commands, menu completion, variable, editing function and option name completion, inline expansion of variables, history commands. Globbing --- extremely powerful, including: recursive globbing (cf. find), file attribute qualifiers (size, type, etc. also cf. find), full alternation and negation of patterns. Handling of multiple redirections (simpler than tee). Large number of options for tailoring. Path expansion (=foo -> /usr/bin/foo). Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). Named directories. Comprehensive integer arithmetic. Manipulation of arrays (including reverse subscripting). Spelling correction. A3) On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question Z2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question A5), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. A4) What's the latest version? Zsh 2.5.0 was the last major release: the final form is 2.5.03. Many bugs were fixed after 2.3.1, which was the previous major release, and there were many new features, notably programmable completion. This version is known to have a bug with pipelines inside other shell structures (now fixed in 2.6). The release of zsh 3.0 is imminent; currently 3.0-pre3 is available. Major zsh sites are particularly encouraged to download this and report any bugs. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation when 3.0 appears should take a look at the list of incompatibilities at the end of Z1). This is longer than usual due to enhanced sh, ksh and POSIX compatibility. Note that even numbered minor versions are not released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question Z1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. A5) Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ Australia ftp://ftp.ips.oz.au/pub/packages/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ ftp://ftp.prz.tu-berlin.de/pub/unix/shells/zsh Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.iij.ad.jp/pub/misc/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.cso.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ (If you don't understand URL's, the first thing after the ftp:// is the hostname and the remainder after the / is the directory. You can supply these directly to a Web browser. If you're reading this with a recent version of Netscape Navigator, you may just have to click on them.) The latest full release is in zsh.tar.gz in these directories. Note that this is in gzip format: you will need GNU gzip from your nearest GNU archive to unpack it. The up-to-the-minute development version is in zsh-beta.tar.gz. There is also a version under RCS control which may be more suitable for source hackers. A6) I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the -l tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as '-zsh', you can link zsh to -zsh (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure -zsh is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Section B: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. B1) Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh. The classic difference is word splitting, discussed in C4); this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, SH_GLOB, SH_WORD_SPLIT (see question C4) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. From 3.0, the command `emulate' is also available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect; those marked - have recently (i.e., between the release and the beta version) become ksh-compatible. Capitalised words with underlines refer to shell options. Syntax: * Shell word splitting: see question C4). * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is available from version 2.6-beta17; note even in this case $array[2] with no braces refers to element 2 of $array, etc. Coprocesses are established by `coproc'; `|&' behaves like csh. - Opening for both input and output via <> is only available from 2.6-beta21; before it performed globbing of any sequence of decimal digits. For the latter, you now need <->. Command line substitutions, globbing etc.: * Failure to match a globbing pattern causes an error (use NO_NOMATCH). * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but * in zsh. (GLOB_SUBST has just been added to fix this.) - On the other hand, `foo=*' does globbing immediately on the right hand side of the assignment (this has changed from 2.6-beta17; the old behaviour now requires the option GLOB_ASSIGN). The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) * $PSn do not do parameter substitution by default (use PROMPT_SUBST). Globbing does not allow ksh-style `pattern-lists'. Equivalents: ------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that ~ is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the ~ operator). As the `**' operator cannot be grouped (inside parentheses it is treated as *), this is the way to exclude some subdirectories from matching a `**'. Unquoted assignments do file expansion after `:'s (intended for PATHs). `integer' does not allow -i. Command execution: * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). $PATH is not searched for commands specified at invocation without -c. Aliases and functions: The order in which aliases and functions are defined is significant (function definitions with () expand aliases -- see question B3). Aliases and functions cannot be exported. There are no tracked aliases: command hashing replaces these. The use of aliases for key bindings is replaced by `bindkey'. * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). - Up to version 2.5, autoloaded functions just contained the body of the function: see C5). Traps and signals: Traps are not local to functions, are not reset automatically when called, and are called as functions themselves (this is a bug for the `trap "..." NAL' form of trap setting). TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). Editing: The options emacs, gmacs, trackall, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' become `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. `Trackall' is replaced by `hashcmds'. The `keyword' option does not exist and -k is instead interactivecomments. (`keyword' will not be in the next ksh release either.) Management of histories in multiple shells is different: the history list is not saved and restored after each command. \ does not escape editing chars (use ^V). Not all ksh bindings are set (e.g. `<ESC>#'; try <ESC>q). * # in an interactive shell is not treated as a comment by default. Built-in commands: Some built-ins (r, autoload, history, integer ...) were aliases in ksh. There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' `jobs' has no `-n' flag. `read' has no `-s' flag. In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' it is treated as an expression). Other idiosyncrasies: `select' always redisplays the list of selections on each loop. B2) Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in scripts/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: Logout, rehash, source, (un)limit built-in commands. *rc file for interactive shells. Directory stacks. Cshjunkie*, ignoreeof options. The CSH_NULL_GLOB option. >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) foreach ... loops; alternative syntax for other loops. Alternative syntax `if ( ... ) ...' (also `for', `which'; this now requires the CSH_JUNKIE_PAREN option). $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... Escape sequences via % for prompts. Special array variables $PATH etc. are colon-separated, $path are arrays. !-type history (which may be turned off via `setopt nobanghist'). Arrays have csh-like features (see under B1)). B3) Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1. If the csh alias references "parameters" (\!:1 \!* etc.), then in zsh you need a function (referencing $1 $* etc.). Otherwise, you can use a zsh alias. 2. If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3. If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4. If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: a. convert all of them to zsh functions; or b. after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5. Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6. Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7. To begin a zsh alias with a - (dash, hyphen) character, use "alias --": csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8. Stay away from "alias -g" in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. B4) Similarities with tcsh: (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with bindkey -s (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. Bindkey -s allows limitless possibilities along these lines. B5) Similarities with bash Zsh has almost all the features that bash has (and much more); in addition it is about twice as fast, though this is less impressive than it sounds. With the new malloc by Sven Wischnowsky (only used if you used `configure --enable-zsh-mem' when configuring), zsh uses about the same amount of heap memory as bash, which was previously the biggest gripe. The only feature I am aware of that zsh doesn't have is setting a numerical value for ignoreeof --- it's always 10 --- but of course I don't use bash :-). On the other hand, zsh is not strictly POSIX compliant --- though the latest beta version is and production version 3 will be very much more so than the last production version, with the appropriate options set or when invoked as sh or ksh --- and will not use GNU readline (zle is more powerful). In fact, bash is intended more as an enhanced sh than a ksh work-alike; it doesn't handle [[ ... ]], or (yet) arrays, for example. Of course, they're working on bash, too. Some zsh-like features are suggested for future versions. B6) Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/shell/\ csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers --- but note it is only slightly larger than bash and tcsh, and uses much less memory and CPU time than tcsh. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Section C: How to get various things to work C1) How do I turn off spelling correction/globbing for an individual command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' (you can have both nocorrect and nglob, if you like). C2) How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes *before* any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. C3) Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that's_ not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: in 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. C4) Why does `$var' where var="foo bar" not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=(\"$sentence\")" after which $words is an array with the words of $sentence, or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or when `emulate ksh' or `emulate sh' are in effect. C5) Why do my autoloaded functions not autoload [the first time]? When you put a shell function in an autoload directory (i.e. one mentioned in $FPATH), it should be written just as if it were a shell script. In other words, there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching '}' at the end. If you include those, then the first time you try to use the function, the _whole_ file is run --- in other words, zsh simply defines the function and does nothing else. As a concrete example, if you have a function which you would define on the command line as `xhead () { print -n "\033]2;$*\a"; }' and your have assigned `FPATH=~/fns', then your .zshrc should contain `autoload xhead' and the file ~/fns/xhead should contain only `print -n "\033]2;$*\a"'. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) The shell has just (version 2.6 beta 5) been enhanced to allow the Korn shell syntax, where the file contains the whole function including the definition lines. However, the form given above is unlikely to disappear as it allows significant benefits, including using a function directly as a script, and being able to link a function under different names. C6) How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is supported from version 2.6 onward). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$[ ... ]' method will always display in decimal. C7) How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. C9) Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. C10) How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. C11) Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. C12) Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (Nohup is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. C13) How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. Section D: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. D1) What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing "CTRL-x g", which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the section I will discuss completion only. D2) What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see D4).) D3) How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via it's options. The default is for it to beep and completion to stop until you type another character. You can type ^D to see all the possible completions. This can be changed by the following options, among others (1) with nobeep set, that annoying beep goes away (2) with autolist set, when the completion is ambiguous you get a list without having to type ^D, (3) with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started (4) with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. D4) How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example 'p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say 'p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, 'p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in D2)), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the -f before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): i) multiple square brackets after a single condition give alternatives: for example, 's[foo][bar]' says apply the completion if the word begins with `foo' or `bar', ii) spaces between conditions mean both must match: for example, 'p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', iii) commas between conditions mean either can match: for example, 'c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. D5) And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question B1); note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. (According to POSIX, this is not a bug with `special' builtins.) `time' is ignored with builtins and can't be used with {...}. `set -x' (`setopt xtrace') still has a few glitches. The :q modifier doesn't split words and -q and -x don't work for variables. In vi mode, `u' can go past the original modification point. The singlelinezle option has problems with prompts containing escapes. The `r' command does not work inside $(...) or `...` expansions. Note that a few recent changes introduce incompatibilities (these are not bugs): Changes since zsh 2.5: From 3.0-pre3, [[, { and } are reserved words, hence must be separated from other characters by whitespace. (This change may be partially backed out since it breaks many scripts.) The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. From 2.6.beta21, <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. From 2.6.beta20, the command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). The current beta version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. The `HISTCHARS' variable is now `histchars'. Currently both are tied together for compatibility. The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. Changes present in zsh 2.5: Assignment of `...` and $(...) to variables in the form `foo=$(...)' is now always scalar; previously the command output was split and array assignment performed if more than one word resulted. You can still generate an array vie `foo=($(...))', which was always the safe way of doing it. Again, this is for Bourne/Korn compliance. (Note the same is true for globbing, as mentioned in B1) above.) The -h option to compctl has been removed (use `-k hosts' for the same effect); automatic handling of hosts after '@' has been removed (use e.g. `compctl -u -x "n[-1,@]" -k hosts -- finger'). Handling of backslashes in `echo' and `print' has changed. umask's behaviour with respect to symbolic operators has reversed (and is now ksh-compatible). The option CSH_JUNKIE_TILDE has been upgraded to GLOB_SUBST: instead of just ~'s and ='s, all characters become eligible for file expansion and globbing when the option is set. (The option was not present in 2.3 at all.) The corresponding one-time switches ${~...}, ${^.,.} and ${=...}, now force the corresponding options on for the evaluation, rather than toggling (double the character to force off). "${#foo}" (with the quotes) now gives an array length if `foo' is an array. ("${(c)#foo}" gives the total character length.) Z2) Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so any suggestions, complaints, questions and matters for discussion should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu The list (everything since May 1992) is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. A useful World Wide Web interface to recent mailings is currently kept at http://www-stud.enst.fr/~tardieu/mailarchive/zsh-list/index.html by Samuel Tardieu. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. Z3) What's on the wish-list? Mostly, a lot of the code needs a major clean-up: particular offenders are the history code (hist.c: this is under way), parameter code (params.c) and substitution code (subst.c). A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. Ksh/sh compatibility could be improved; this is a useful long term goal. Option for glob qualifiers to follow perl syntax. Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. trap '...' FOO should be eval'd rather than called as a function. `PATH=' should clear the PATH: it inserts `.'; use `unset PATH' or `path=()' for the time being. This is not really a bug as the . would be used internally in any case (cf. ksh). Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wishnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.mal.com/zsh/".
[This is early due to my being about to go on holiday for two weeks in about ten minutes' time. References to 3.0 are therefore a few hours premature --- pws] Archive-Name: unix-faq/shell/zsh Last-Modified: 1996/08/15 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zsh.FAQ,v 2.18 1996/08/15 16:15:34 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996 (see end of document) Changes since last issue: - in A4: 3.0 (almost) released! remove remark about even-numbered minor versions - in B1: clearer summary of sh/ksh compatibility removed <> incompatibility note (now see under Z1) ditto GLOB_ASSIGN - in C5: note this problem is now historical - in Z1: PRINT_EXIT_VALUE and NO_CLOBBER swapped changes in calling of traps changes now reflect 3.0; changes up to 2.5 deleted This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. In fact, zsh is currently the most powerful freely available shell. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question A5); if you want to know what to do with insoluble problems, go to Z2). Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Section A: Introducing zsh and how to install it A0) Sources of information A1) What is it? A2) What is good at? A3) On what machines will it run? (Plus important compilation notes) A4) What's the latest version? A5) Where do I get it? A6) I don't have root access: how do I make zsh my login shell? Section B: How does zsh differ from...? B1) sh and ksh? B2) csh? B3) Why do my csh aliases not work? (Plus other alias pitfalls.) B4) tcsh? B5) bash? B6) Shouldn't zsh be more/less like ksh/(t)csh? Section C: How to get various things to work C1) How do I turn off spelling correction/globbing for an individual command? C2) How do I get the meta key to work on my xterm? C3) Why does my terminal act funny in some way? C4) Why does `$var' where var="foo bar" not do what I expect? C5) Why do my autoloaded functions not autoload [the first time]? C6) How does base arithmetic work? C7) How do I get a newline in my prompt? C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? C9) Why can't I bind \C-s and \C-q any more? C10) How do I execute command `foo' within function `foo'? C11) Why do history substitutions with single bangs do something funny? C12) Why does zsh kill off all my background jobs when I logout? C13) How do I list all my history entries? Section D: The mysteries of completion D1) What is completion? D2) What sorts of things can be completed? D3) How does zsh deal with ambiguous completions? D4) How do I get started with programmable completion? D5) And if programmable completion isn't good enough? Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Z2) Where do I report bugs, get more info / who's working on zsh? Z3) What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Section A: Introducing zsh and how to install it A0) Sources of information Information on zsh is now available via the World Wide Web. The URL is "http://www.mal.com/zsh/". The server provides this FAQ and much else (thanks to Mark Borges for this). The FAQ is at "http://www.mal.com/zsh/FAQ/". Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question A5). (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question Z2). A1) What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); it's compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question Z2). Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. A2) What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major feature in any other freely-available shell which zsh does not also have (except smallness). Command line editing: programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), multi-line commands editable as a single buffer (even files!), variable editing (vared), command buffer stack, print text straight into the buffer for immediate editing (print -z), execution of unbound commands, menu completion, variable, editing function and option name completion, inline expansion of variables, history commands. Globbing --- extremely powerful, including: recursive globbing (cf. find), file attribute qualifiers (size, type, etc. also cf. find), full alternation and negation of patterns. Handling of multiple redirections (simpler than tee). Large number of options for tailoring. Path expansion (=foo -> /usr/bin/foo). Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). Named directories. Comprehensive integer arithmetic. Manipulation of arrays (including reverse subscripting). Spelling correction. A3) On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question Z2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question A5), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. A4) What's the latest version? Zsh 3.0 is about to be relased. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of Z1). This is longer than usual due to enhanced sh, ksh and POSIX compatibility. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question Z1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. A5) Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ Australia ftp://ftp.ips.oz.au/pub/packages/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ ftp://ftp.prz.tu-berlin.de/pub/unix/shells/zsh Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.iij.ad.jp/pub/misc/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.cso.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ (If you don't understand URL's, the first thing after the ftp:// is the hostname and the remainder after the / is the directory. You can supply these directly to a Web browser. If you're reading this with a recent version of Netscape Navigator, you may just have to click on them.) The latest full release is in zsh.tar.gz in these directories. Note that this is in gzip format: you will need GNU gzip from your nearest GNU archive to unpack it. The up-to-the-minute development version is in zsh-beta.tar.gz. There is also a version under RCS control which may be more suitable for source hackers. A6) I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the -l tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as '-zsh', you can link zsh to -zsh (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure -zsh is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Section B: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. B1) Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: i) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; ii) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); iii) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; iv) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; v) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in C4); this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question C4) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. Syntax: * Shell word splitting: see question C4). * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. Coprocesses are established by `coproc'; `|&' behaves like csh. Command line substitutions, globbing etc.: * Failure to match a globbing pattern causes an error (use NO_NOMATCH). * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but * in zsh. (GLOB_SUBST has been added to fix this.) The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) * $PSn do not do parameter substitution by default (use PROMPT_SUBST). Globbing does not allow ksh-style `pattern-lists'. Equivalents: ------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that ~ is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the ~ operator). As the `**' operator cannot be grouped (inside parentheses it is treated as *), this is the way to exclude some subdirectories from matching a `**'. Unquoted assignments do file expansion after `:'s (intended for PATHs). `integer' does not allow -i. Command execution: * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). $PATH is not searched for commands specified at invocation without -c. Aliases and functions: The order in which aliases and functions are defined is significant (function definitions with () expand aliases -- see question B3). Aliases and functions cannot be exported. There are no tracked aliases: command hashing replaces these. The use of aliases for key bindings is replaced by `bindkey'. * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). Traps and signals: Traps are not local to functions. TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). Editing: The options emacs, gmacs, trackall, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' become `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. `Trackall' is replaced by `hashcmds'. The `keyword' option does not exist and -k is instead interactivecomments. (`keyword' will not be in the next ksh release either.) Management of histories in multiple shells is different: the history list is not saved and restored after each command. \ does not escape editing chars (use ^V). Not all ksh bindings are set (e.g. `<ESC>#'; try <ESC>q). * # in an interactive shell is not treated as a comment by default. Built-in commands: Some built-ins (r, autoload, history, integer ...) were aliases in ksh. There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' `jobs' has no `-n' flag. `read' has no `-s' flag. In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' it is treated as an expression). Other idiosyncrasies: `select' always redisplays the list of selections on each loop. B2) Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in scripts/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: Logout, rehash, source, (un)limit built-in commands. *rc file for interactive shells. Directory stacks. Cshjunkie*, ignoreeof options. The CSH_NULL_GLOB option. >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) foreach ... loops; alternative syntax for other loops. Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'). $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... Escape sequences via % for prompts. Special array variables $PATH etc. are colon-separated, $path are arrays. !-type history (which may be turned off via `setopt nobanghist'). Arrays have csh-like features (see under B1)). B3) Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1. If the csh alias references "parameters" (\!:1 \!* etc.), then in zsh you need a function (referencing $1 $* etc.). Otherwise, you can use a zsh alias. 2. If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3. If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4. If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: a. convert all of them to zsh functions; or b. after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5. Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6. Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7. To begin a zsh alias with a - (dash, hyphen) character, use "alias --": csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8. Stay away from "alias -g" in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. B4) Similarities with tcsh: (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with bindkey -s (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. Bindkey -s allows limitless possibilities along these lines. B5) Similarities with bash Zsh has almost all the features that bash has (and much more); in addition it is about twice as fast, though this is less impressive than it sounds. With the new malloc by Sven Wischnowsky (only used if you used `configure --enable-zsh-mem' when configuring), zsh uses about the same amount of heap memory as bash, which was previously the biggest gripe. The only feature I am aware of that zsh doesn't have is setting a numerical value for ignoreeof --- it's always 10 --- but of course I don't use bash :-). On the other hand, zsh is not strictly POSIX compliant --- though the latest beta version is and production version 3 will be very much more so than the last production version, with the appropriate options set or when invoked as sh or ksh --- and will not use GNU readline (zle is more powerful). In fact, bash is intended more as an enhanced sh than a ksh work-alike; it doesn't handle [[ ... ]], or (yet) arrays, for example. Of course, they're working on bash, too. Some zsh-like features are suggested for future versions. B6) Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/shell/\ csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers --- but note it is only slightly larger than bash and tcsh, and uses much less memory and CPU time than tcsh. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Section C: How to get various things to work C1) How do I turn off spelling correction/globbing for an individual command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' (you can have both nocorrect and nglob, if you like). C2) How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes *before* any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. C3) Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that's_ not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. C4) Why does `$var' where var="foo bar" not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=(\"$sentence\")" after which $words is an array with the words of $sentence, or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or when `emulate ksh' or `emulate sh' is in effect. C5) Why do my autoloaded functions not autoload [the first time]? (Before version 3.0, autoloading in the Korn shell way was not allowed; this article is now a historical artefact and will eventually be removed. Note, however, that the old form of autoloading is still allowed and there are no plans to remove it.) When you put a shell function in an autoload directory (i.e. one mentioned in $FPATH), it should be written just as if it were a shell script. In other words, there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching '}' at the end. If you include those, then the first time you try to use the function, the _whole_ file is run --- in other words, zsh simply defines the function and does nothing else. As a concrete example, if you have a function which you would define on the command line as `xhead () { print -n "\033]2;$*\a"; }' and your have assigned `FPATH=~/fns', then your .zshrc should contain `autoload xhead' and the file ~/fns/xhead should contain only `print -n "\033]2;$*\a"'. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) C6) How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$[ ... ]' method will always display in decimal. C7) How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. C9) Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. C10) How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. C11) Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. C12) Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (Nohup is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. C13) How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. Section D: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. D1) What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing "CTRL-x g", which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the section I will discuss completion only. D2) What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see D4).) D3) How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via it's options. The default is for it to beep and completion to stop until you type another character. You can type ^D to see all the possible completions. This can be changed by the following options, among others (1) with nobeep set, that annoying beep goes away (2) with autolist set, when the completion is ambiguous you get a list without having to type ^D, (3) with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started (4) with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. D4) How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example 'p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say 'p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, 'p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in D2)), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the -f before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): i) multiple square brackets after a single condition give alternatives: for example, 's[foo][bar]' says apply the completion if the word begins with `foo' or `bar', ii) spaces between conditions mean both must match: for example, 'p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', iii) commas between conditions mean either can match: for example, 'c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. D5) And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question B1); note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. (According to POSIX, this is not a bug with `special' builtins.) `time' is ignored with builtins and can't be used with {...}. `set -x' (`setopt xtrace') still has a few glitches. The :q modifier doesn't split words and -q and -x don't work for variables. In vi mode, `u' can go past the original modification point. The singlelinezle option has problems with prompts containing escapes. The `r' command does not work inside $(...) or `...` expansions. Note that a few recent changes introduce incompatibilities (these are not bugs): Changes since zsh 2.5: Signal traps established with the `trap' builtin are now called with the environment of the caller, instead of as a new function level, as in ksh. Traps established as functions (e.g. `TRAPINT() {...}') work as before. The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. On the other hand, `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. The `HISTCHARS' variable is now `histchars'. Currently both are tied together for compatibility. The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. Z2) Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so any suggestions, complaints, questions and matters for discussion should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. Z3) What's on the wish-list? Mostly, a lot of the code needs a major clean-up: particular offenders are the history code (hist.c: this is under way), parameter code (params.c) and substitution code (subst.c). A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. Ksh/sh compatibility could be improved; this is a useful long term goal. Option for glob qualifiers to follow perl syntax. Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. trap '...' FOO should be eval'd rather than called as a function. `PATH=' should clear the PATH: it inserts `.'; use `unset PATH' or `path=()' for the time being. This is not really a bug as the . would be used internally in any case (cf. ksh). Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.mal.com/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1996/09/25 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zsh.FAQ,v 2.19 1996/09/25 07:32:16 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996 (see end of document) Changes since last issue: - in A4: 3.0.0 actually released, 3.0.1 under test - in C4: fixed `eval' splitting example, whoops - D3: added to and rewritten - in Z1: added =(...) bug This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. In fact, zsh is currently the most powerful freely available shell. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question A5); if you want to know what to do with insoluble problems, go to Z2). Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Section A: Introducing zsh and how to install it A0) Sources of information A1) What is it? A2) What is it good at? A3) On what machines will it run? (Plus important compilation notes) A4) What's the latest version? A5) Where do I get it? A6) I don't have root access: how do I make zsh my login shell? Section B: How does zsh differ from...? B1) sh and ksh? B2) csh? B3) Why do my csh aliases not work? (Plus other alias pitfalls.) B4) tcsh? B5) bash? B6) Shouldn't zsh be more/less like ksh/(t)csh? Section C: How to get various things to work C1) How do I turn off spelling correction/globbing for an individual command? C2) How do I get the meta key to work on my xterm? C3) Why does my terminal act funny in some way? C4) Why does `$var' where var="foo bar" not do what I expect? C5) Why do my autoloaded functions not autoload [the first time]? C6) How does base arithmetic work? C7) How do I get a newline in my prompt? C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? C9) Why can't I bind \C-s and \C-q any more? C10) How do I execute command `foo' within function `foo'? C11) Why do history substitutions with single bangs do something funny? C12) Why does zsh kill off all my background jobs when I logout? C13) How do I list all my history entries? Section D: The mysteries of completion D1) What is completion? D2) What sorts of things can be completed? D3) How does zsh deal with ambiguous completions? D4) How do I get started with programmable completion? D5) And if programmable completion isn't good enough? Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Z2) Where do I report bugs, get more info / who's working on zsh? Z3) What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Section A: Introducing zsh and how to install it A0) Sources of information Information on zsh is now available via the World Wide Web. The URL is "http://www.mal.com/zsh/". The server provides this FAQ and much else (thanks to Mark Borges for this). The FAQ is at "http://www.mal.com/zsh/FAQ/". Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question A5). (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question Z2). A1) What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); it's compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question Z2). Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. A2) What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major feature in any other freely-available shell which zsh does not also have (except smallness). Command line editing: programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), multi-line commands editable as a single buffer (even files!), variable editing (vared), command buffer stack, print text straight into the buffer for immediate editing (print -z), execution of unbound commands, menu completion, variable, editing function and option name completion, inline expansion of variables, history commands. Globbing --- extremely powerful, including: recursive globbing (cf. find), file attribute qualifiers (size, type, etc. also cf. find), full alternation and negation of patterns. Handling of multiple redirections (simpler than tee). Large number of options for tailoring. Path expansion (=foo -> /usr/bin/foo). Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). Named directories. Comprehensive integer arithmetic. Manipulation of arrays (including reverse subscripting). Spelling correction. A3) On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question Z2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question A5), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. A4) What's the latest version? Zsh 3.0.0 has now been relased; 3.0.1 is under test. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of Z1). This is longer than usual due to enhanced sh, ksh and POSIX compatibility. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question Z1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. A5) Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ Australia ftp://ftp.ips.oz.au/pub/packages/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ ftp://ftp.prz.tu-berlin.de/pub/unix/shells/zsh Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.iij.ad.jp/pub/misc/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.cso.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ (If you don't understand URL's, the first thing after the ftp:// is the hostname and the remainder after the / is the directory. You can supply these directly to a Web browser. If you're reading this with a recent version of Netscape Navigator, you may just have to click on them.) The latest full release is in zsh.tar.gz in these directories. Note that this is in gzip format: you will need GNU gzip from your nearest GNU archive to unpack it. The up-to-the-minute development version is in zsh-beta.tar.gz. There is also a version under RCS control which may be more suitable for source hackers. A6) I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the -l tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as '-zsh', you can link zsh to -zsh (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure -zsh is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Section B: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. B1) Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: i) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; ii) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); iii) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; iv) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; v) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in C4); this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question C4) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. Syntax: * Shell word splitting: see question C4). * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. Coprocesses are established by `coproc'; `|&' behaves like csh. Command line substitutions, globbing etc.: * Failure to match a globbing pattern causes an error (use NO_NOMATCH). * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but * in zsh. (GLOB_SUBST has been added to fix this.) The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) * $PSn do not do parameter substitution by default (use PROMPT_SUBST). Globbing does not allow ksh-style `pattern-lists'. Equivalents: ------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that ~ is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the ~ operator). As the `**' operator cannot be grouped (inside parentheses it is treated as *), this is the way to exclude some subdirectories from matching a `**'. Unquoted assignments do file expansion after `:'s (intended for PATHs). `integer' does not allow -i. Command execution: * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). $PATH is not searched for commands specified at invocation without -c. Aliases and functions: The order in which aliases and functions are defined is significant (function definitions with () expand aliases -- see question B3). Aliases and functions cannot be exported. There are no tracked aliases: command hashing replaces these. The use of aliases for key bindings is replaced by `bindkey'. * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). Traps and signals: Traps are not local to functions. TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). Editing: The options emacs, gmacs, trackall, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' become `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. `Trackall' is replaced by `hashcmds'. The `keyword' option does not exist and -k is instead interactivecomments. (`keyword' will not be in the next ksh release either.) Management of histories in multiple shells is different: the history list is not saved and restored after each command. \ does not escape editing chars (use ^V). Not all ksh bindings are set (e.g. `<ESC>#'; try <ESC>q). * # in an interactive shell is not treated as a comment by default. Built-in commands: Some built-ins (r, autoload, history, integer ...) were aliases in ksh. There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' `jobs' has no `-n' flag. `read' has no `-s' flag. In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' it is treated as an expression). Other idiosyncrasies: `select' always redisplays the list of selections on each loop. B2) Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in scripts/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: Logout, rehash, source, (un)limit built-in commands. *rc file for interactive shells. Directory stacks. Cshjunkie*, ignoreeof options. The CSH_NULL_GLOB option. >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) foreach ... loops; alternative syntax for other loops. Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'). $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... Escape sequences via % for prompts. Special array variables $PATH etc. are colon-separated, $path are arrays. !-type history (which may be turned off via `setopt nobanghist'). Arrays have csh-like features (see under B1)). B3) Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1. If the csh alias references "parameters" (\!:1 \!* etc.), then in zsh you need a function (referencing $1 $* etc.). Otherwise, you can use a zsh alias. 2. If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3. If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4. If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: a. convert all of them to zsh functions; or b. after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5. Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6. Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7. To begin a zsh alias with a - (dash, hyphen) character, use "alias --": csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8. Stay away from "alias -g" in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. B4) Similarities with tcsh: (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with bindkey -s (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. Bindkey -s allows limitless possibilities along these lines. B5) Similarities with bash Zsh has almost all the features that bash has (and much more); in addition it is about twice as fast, though this is less impressive than it sounds. With the new malloc by Sven Wischnowsky (only used if you used `configure --enable-zsh-mem' when configuring), zsh uses about the same amount of heap memory as bash, which was previously the biggest gripe. The only feature I am aware of that zsh doesn't have is setting a numerical value for ignoreeof --- it's always 10 --- but of course I don't use bash :-). On the other hand, zsh is not strictly POSIX compliant --- though the latest beta version is and production version 3 will be very much more so than the last production version, with the appropriate options set or when invoked as sh or ksh --- and will not use GNU readline (zle is more powerful). In fact, bash is intended more as an enhanced sh than a ksh work-alike; it doesn't handle [[ ... ]], or (yet) arrays, for example. Of course, they're working on bash, too. Some zsh-like features are suggested for future versions. B6) Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/shell/\ csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers --- but note it is only slightly larger than bash and tcsh, and uses much less memory and CPU time than tcsh. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Section C: How to get various things to work C1) How do I turn off spelling correction/globbing for an individual command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' (you can have both nocorrect and nglob, if you like). C2) How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes *before* any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. C3) Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that's_ not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. C4) Why does `$var' where var="foo bar" not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. C5) Why do my autoloaded functions not autoload [the first time]? (Before version 3.0, autoloading in the Korn shell way was not allowed; this article is now a historical artefact and will eventually be removed. Note, however, that the old form of autoloading is still allowed and there are no plans to remove it.) When you put a shell function in an autoload directory (i.e. one mentioned in $FPATH), it should be written just as if it were a shell script. In other words, there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching '}' at the end. If you include those, then the first time you try to use the function, the _whole_ file is run --- in other words, zsh simply defines the function and does nothing else. As a concrete example, if you have a function which you would define on the command line as `xhead () { print -n "\033]2;$*\a"; }' and your have assigned `FPATH=~/fns', then your .zshrc should contain `autoload xhead' and the file ~/fns/xhead should contain only `print -n "\033]2;$*\a"'. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) C6) How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$[ ... ]' method will always display in decimal. C7) How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. C9) Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. C10) How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. C11) Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. C12) Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (Nohup is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. C13) How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. Section D: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. D1) What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing "CTRL-x g", which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the section I will discuss completion only. D2) What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see D4).) D3) How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via it's options. The default is for it to beep and completion to stop until you type another character. You can type ^D to see all the possible completions. This can be changed by the following options, among others: - with nobeep set, that annoying beep goes away - with nolistbeep, beeping is only turned off for ambiguous completions - with autolist set, when the completion is ambiguous you get a list without having to type ^D - with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted - with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started - with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. D4) How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example 'p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say 'p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, 'p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in D2)), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the -f before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): i) multiple square brackets after a single condition give alternatives: for example, 's[foo][bar]' says apply the completion if the word begins with `foo' or `bar', ii) spaces between conditions mean both must match: for example, 'p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', iii) commas between conditions mean either can match: for example, 'c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. D5) And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question B1); note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. (According to POSIX, this is not a bug with `special' builtins.) `time' is ignored with builtins and can't be used with {...}. `set -x' (`setopt xtrace') still has a few glitches. The :q modifier doesn't split words and -q and -x don't work for variables. In vi mode, `u' can go past the original modification point. The singlelinezle option has problems with prompts containing escapes. The `r' command does not work inside $(...) or `...` expansions. The file produced by =(...) substitution is removed too early if the substitution appears as an argument to a shell function. Note that a few recent changes introduce incompatibilities (these are not bugs): Changes since zsh 2.5: Signal traps established with the `trap' builtin are now called with the environment of the caller, instead of as a new function level, as in ksh. Traps established as functions (e.g. `TRAPINT() {...}') work as before. The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. On the other hand, `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. The `HISTCHARS' variable is now `histchars'. Currently both are tied together for compatibility. The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. Z2) Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so any suggestions, complaints, questions and matters for discussion should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. Z3) What's on the wish-list? Mostly, a lot of the code needs a major clean-up: particular offenders are the history code (hist.c: this is under way), parameter code (params.c) and substitution code (subst.c). A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. Ksh/sh compatibility could be improved; this is a useful long term goal. Option for glob qualifiers to follow perl syntax. Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. trap '...' FOO should be eval'd rather than called as a function. `PATH=' should clear the PATH: it inserts `.'; use `unset PATH' or `path=()' for the time being. This is not really a bug as the . would be used internally in any case (cf. ksh). Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.mal.com/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1996/10/24 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zsh.FAQ,v 2.20 1996/10/24 09:15:18 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996 (see end of document) Changes since last issue: - in Z1: removed =(...) bug again mention pushd change This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. In fact, zsh is currently the most powerful freely available shell. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question A5); if you want to know what to do with insoluble problems, go to Z2). Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Section A: Introducing zsh and how to install it A0) Sources of information A1) What is it? A2) What is it good at? A3) On what machines will it run? (Plus important compilation notes) A4) What's the latest version? A5) Where do I get it? A6) I don't have root access: how do I make zsh my login shell? Section B: How does zsh differ from...? B1) sh and ksh? B2) csh? B3) Why do my csh aliases not work? (Plus other alias pitfalls.) B4) tcsh? B5) bash? B6) Shouldn't zsh be more/less like ksh/(t)csh? Section C: How to get various things to work C1) How do I turn off spelling correction/globbing for an individual command? C2) How do I get the meta key to work on my xterm? C3) Why does my terminal act funny in some way? C4) Why does `$var' where var="foo bar" not do what I expect? C5) Why do my autoloaded functions not autoload [the first time]? C6) How does base arithmetic work? C7) How do I get a newline in my prompt? C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? C9) Why can't I bind \C-s and \C-q any more? C10) How do I execute command `foo' within function `foo'? C11) Why do history substitutions with single bangs do something funny? C12) Why does zsh kill off all my background jobs when I logout? C13) How do I list all my history entries? Section D: The mysteries of completion D1) What is completion? D2) What sorts of things can be completed? D3) How does zsh deal with ambiguous completions? D4) How do I get started with programmable completion? D5) And if programmable completion isn't good enough? Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Z2) Where do I report bugs, get more info / who's working on zsh? Z3) What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Section A: Introducing zsh and how to install it A0) Sources of information Information on zsh is now available via the World Wide Web. The URL is "http://www.mal.com/zsh/". The server provides this FAQ and much else (thanks to Mark Borges for this). The FAQ is at "http://www.mal.com/zsh/FAQ/". Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question A5). (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question Z2). A1) What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); it's compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question Z2). Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. A2) What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major feature in any other freely-available shell which zsh does not also have (except smallness). Command line editing: programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), multi-line commands editable as a single buffer (even files!), variable editing (vared), command buffer stack, print text straight into the buffer for immediate editing (print -z), execution of unbound commands, menu completion, variable, editing function and option name completion, inline expansion of variables, history commands. Globbing --- extremely powerful, including: recursive globbing (cf. find), file attribute qualifiers (size, type, etc. also cf. find), full alternation and negation of patterns. Handling of multiple redirections (simpler than tee). Large number of options for tailoring. Path expansion (=foo -> /usr/bin/foo). Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). Named directories. Comprehensive integer arithmetic. Manipulation of arrays (including reverse subscripting). Spelling correction. A3) On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question Z2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question A5), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. A4) What's the latest version? Zsh 3.0.0 has now been relased; 3.0.1 is under test. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of Z1). This is longer than usual due to enhanced sh, ksh and POSIX compatibility. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question Z1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. A5) Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ Australia ftp://ftp.ips.gov.au/mirror/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ ftp://ftp.prz.tu-berlin.de/pub/unix/shells/zsh Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.iij.ad.jp/pub/misc/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.cso.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ (If you don't understand URL's, the first thing after the ftp:// is the hostname and the remainder after the / is the directory. You can supply these directly to a Web browser. If you're reading this with a recent version of Netscape Navigator, you may just have to click on them.) The latest full release is in zsh.tar.gz in these directories. Note that this is in gzip format: you will need GNU gzip from your nearest GNU archive to unpack it. The up-to-the-minute development version is in zsh-beta.tar.gz. There is also a version under RCS control which may be more suitable for source hackers. A6) I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the -l tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as '-zsh', you can link zsh to -zsh (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure -zsh is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Section B: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. B1) Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: i) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; ii) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); iii) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; iv) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; v) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in C4); this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question C4) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. Syntax: * Shell word splitting: see question C4). * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. Coprocesses are established by `coproc'; `|&' behaves like csh. Command line substitutions, globbing etc.: * Failure to match a globbing pattern causes an error (use NO_NOMATCH). * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but * in zsh. (GLOB_SUBST has been added to fix this.) The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) * $PSn do not do parameter substitution by default (use PROMPT_SUBST). Globbing does not allow ksh-style `pattern-lists'. Equivalents: ------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that ~ is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the ~ operator). As the `**' operator cannot be grouped (inside parentheses it is treated as *), this is the way to exclude some subdirectories from matching a `**'. Unquoted assignments do file expansion after `:'s (intended for PATHs). `integer' does not allow -i. Command execution: * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). $PATH is not searched for commands specified at invocation without -c. Aliases and functions: The order in which aliases and functions are defined is significant (function definitions with () expand aliases -- see question B3). Aliases and functions cannot be exported. There are no tracked aliases: command hashing replaces these. The use of aliases for key bindings is replaced by `bindkey'. * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). Traps and signals: Traps are not local to functions. TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). Editing: The options emacs, gmacs, trackall, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' become `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. `Trackall' is replaced by `hashcmds'. The `keyword' option does not exist and -k is instead interactivecomments. (`keyword' will not be in the next ksh release either.) Management of histories in multiple shells is different: the history list is not saved and restored after each command. \ does not escape editing chars (use ^V). Not all ksh bindings are set (e.g. `<ESC>#'; try <ESC>q). * # in an interactive shell is not treated as a comment by default. Built-in commands: Some built-ins (r, autoload, history, integer ...) were aliases in ksh. There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' `jobs' has no `-n' flag. `read' has no `-s' flag. In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' it is treated as an expression). Other idiosyncrasies: `select' always redisplays the list of selections on each loop. B2) Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in scripts/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: Logout, rehash, source, (un)limit built-in commands. *rc file for interactive shells. Directory stacks. Cshjunkie*, ignoreeof options. The CSH_NULL_GLOB option. >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) foreach ... loops; alternative syntax for other loops. Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'). $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... Escape sequences via % for prompts. Special array variables $PATH etc. are colon-separated, $path are arrays. !-type history (which may be turned off via `setopt nobanghist'). Arrays have csh-like features (see under B1)). B3) Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1. If the csh alias references "parameters" (\!:1 \!* etc.), then in zsh you need a function (referencing $1 $* etc.). Otherwise, you can use a zsh alias. 2. If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3. If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4. If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: a. convert all of them to zsh functions; or b. after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5. Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6. Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7. To begin a zsh alias with a - (dash, hyphen) character, use "alias --": csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8. Stay away from "alias -g" in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. B4) Similarities with tcsh: (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with bindkey -s (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. Bindkey -s allows limitless possibilities along these lines. B5) Similarities with bash Zsh has almost all the features that bash has (and much more); in addition it is about twice as fast, though this is less impressive than it sounds. With the new malloc by Sven Wischnowsky (only used if you used `configure --enable-zsh-mem' when configuring), zsh uses about the same amount of heap memory as bash, which was previously the biggest gripe. The only feature I am aware of that zsh doesn't have is setting a numerical value for ignoreeof --- it's always 10 --- but of course I don't use bash :-). On the other hand, zsh is not strictly POSIX compliant --- though the latest beta version is and production version 3 will be very much more so than the last production version, with the appropriate options set or when invoked as sh or ksh --- and will not use GNU readline (zle is more powerful). In fact, bash is intended more as an enhanced sh than a ksh work-alike; it doesn't handle [[ ... ]], or (yet) arrays, for example. Of course, they're working on bash, too. Some zsh-like features are suggested for future versions. B6) Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/shell/\ csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers --- but note it is only slightly larger than bash and tcsh, and uses much less memory and CPU time than tcsh. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Section C: How to get various things to work C1) How do I turn off spelling correction/globbing for an individual command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' (you can have both nocorrect and nglob, if you like). C2) How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes *before* any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. C3) Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that's_ not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. C4) Why does `$var' where var="foo bar" not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. C5) Why do my autoloaded functions not autoload [the first time]? (Before version 3.0, autoloading in the Korn shell way was not allowed; this article is now a historical artefact and will eventually be removed. Note, however, that the old form of autoloading is still allowed and there are no plans to remove it.) When you put a shell function in an autoload directory (i.e. one mentioned in $FPATH), it should be written just as if it were a shell script. In other words, there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching '}' at the end. If you include those, then the first time you try to use the function, the _whole_ file is run --- in other words, zsh simply defines the function and does nothing else. As a concrete example, if you have a function which you would define on the command line as `xhead () { print -n "\033]2;$*\a"; }' and your have assigned `FPATH=~/fns', then your .zshrc should contain `autoload xhead' and the file ~/fns/xhead should contain only `print -n "\033]2;$*\a"'. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) C6) How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$[ ... ]' method will always display in decimal. C7) How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. C9) Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. C10) How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. C11) Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. C12) Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (Nohup is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. C13) How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. Section D: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. D1) What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing "CTRL-x g", which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the section I will discuss completion only. D2) What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see D4).) D3) How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via it's options. The default is for it to beep and completion to stop until you type another character. You can type ^D to see all the possible completions. This can be changed by the following options, among others: - with nobeep set, that annoying beep goes away - with nolistbeep, beeping is only turned off for ambiguous completions - with autolist set, when the completion is ambiguous you get a list without having to type ^D - with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted - with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started - with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. D4) How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example 'p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say 'p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, 'p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in D2)), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the -f before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): i) multiple square brackets after a single condition give alternatives: for example, 's[foo][bar]' says apply the completion if the word begins with `foo' or `bar', ii) spaces between conditions mean both must match: for example, 'p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', iii) commas between conditions mean either can match: for example, 'c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. D5) And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question B1); note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. (According to POSIX, this is not a bug with `special' builtins.) `time' is ignored with builtins and can't be used with {...}. `set -x' (`setopt xtrace') still has a few glitches. The :q modifier doesn't split words and -q and -x don't work for variables. In vi mode, `u' can go past the original modification point. The singlelinezle option has problems with prompts containing escapes. The `r' command does not work inside $(...) or `...` expansions. Note that a few recent changes introduce incompatibilities (these are not bugs): Changes since zsh 2.5: Signal traps established with the `trap' builtin are now called with the environment of the caller, instead of as a new function level, as in ksh. Traps established as functions (e.g. `TRAPINT() {...}') work as before. The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. On the other hand, `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. The `HISTCHARS' variable is now `histchars'. Currently both are tied together for compatibility. The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. Z2) Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so any suggestions, complaints, questions and matters for discussion should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. Z3) What's on the wish-list? Mostly, a lot of the code needs a major clean-up: particular offenders are the history code (hist.c: this is under way), parameter code (params.c) and substitution code (subst.c). A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. Ksh/sh compatibility could be improved; this is a useful long term goal. Option for glob qualifiers to follow perl syntax. Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. trap '...' FOO should be eval'd rather than called as a function. `PATH=' should clear the PATH: it inserts `.'; use `unset PATH' or `path=()' for the time being. This is not really a bug as the . would be used internally in any case (cf. ksh). Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.mal.com/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1996/11/25 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zsh.FAQ,v 2.21 1996/11/25 09:13:28 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996 (see end of document) Changes since last issue: in intro: change unnecessarily provocative statement in A4): latest versions are 3.0.1 (production), 3.1.0 (test) in B5) and B6): avoid hostages to fortune in Z1): note about typeset in Z2): note about reporting bugs in Z3): rewrite code cleanup bit, mention modules, delete the 'trap' note (no longer applies). This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question A5); if you want to know what to do with insoluble problems, go to Z2). Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Section A: Introducing zsh and how to install it A0) Sources of information A1) What is it? A2) What is it good at? A3) On what machines will it run? (Plus important compilation notes) A4) What's the latest version? A5) Where do I get it? A6) I don't have root access: how do I make zsh my login shell? Section B: How does zsh differ from...? B1) sh and ksh? B2) csh? B3) Why do my csh aliases not work? (Plus other alias pitfalls.) B4) tcsh? B5) bash? B6) Shouldn't zsh be more/less like ksh/(t)csh? Section C: How to get various things to work C1) How do I turn off spelling correction/globbing for an individual command? C2) How do I get the meta key to work on my xterm? C3) Why does my terminal act funny in some way? C4) Why does `$var' where var="foo bar" not do what I expect? C5) Why do my autoloaded functions not autoload [the first time]? C6) How does base arithmetic work? C7) How do I get a newline in my prompt? C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? C9) Why can't I bind \C-s and \C-q any more? C10) How do I execute command `foo' within function `foo'? C11) Why do history substitutions with single bangs do something funny? C12) Why does zsh kill off all my background jobs when I logout? C13) How do I list all my history entries? Section D: The mysteries of completion D1) What is completion? D2) What sorts of things can be completed? D3) How does zsh deal with ambiguous completions? D4) How do I get started with programmable completion? D5) And if programmable completion isn't good enough? Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Z2) Where do I report bugs, get more info / who's working on zsh? Z3) What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Section A: Introducing zsh and how to install it A0) Sources of information Information on zsh is now available via the World Wide Web. The URL is "http://www.mal.com/zsh/". The server provides this FAQ and much else (thanks to Mark Borges for this). The FAQ is at "http://www.mal.com/zsh/FAQ/". Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question A5). (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question Z2). A1) What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); it's compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question Z2). Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. A2) What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). Command line editing: programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), multi-line commands editable as a single buffer (even files!), variable editing (vared), command buffer stack, print text straight into the buffer for immediate editing (print -z), execution of unbound commands, menu completion, variable, editing function and option name completion, inline expansion of variables, history commands. Globbing --- extremely powerful, including: recursive globbing (cf. find), file attribute qualifiers (size, type, etc. also cf. find), full alternation and negation of patterns. Handling of multiple redirections (simpler than tee). Large number of options for tailoring. Path expansion (=foo -> /usr/bin/foo). Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). Named directories. Comprehensive integer arithmetic. Manipulation of arrays (including reverse subscripting). Spelling correction. A3) On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question Z2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question A5), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. A4) What's the latest version? Zsh 3.0.1 has now been relased. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of Z1). This is longer than usual due to enhanced sh, ksh and POSIX compatibility. Version 3.1.0 is under test, though an intermediate bugfix release 3.0.2 is also expected. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question Z1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. A5) Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ Australia ftp://ftp.ips.gov.au/mirror/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ ftp://ftp.prz.tu-berlin.de/pub/unix/shells/zsh Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.iij.ad.jp/pub/misc/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.cso.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ (If you don't understand URL's, the first thing after the ftp:// is the hostname and the remainder after the / is the directory. You can supply these directly to a Web browser. If you're reading this with a recent version of Netscape Navigator, you may just have to click on them.) The latest full release is in zsh.tar.gz in these directories. Note that this is in gzip format: you will need GNU gzip from your nearest GNU archive to unpack it. The up-to-the-minute development version is in zsh-beta.tar.gz. There is also a version under RCS control which may be more suitable for source hackers. A6) I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the -l tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as '-zsh', you can link zsh to -zsh (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure -zsh is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Section B: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. B1) Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: i) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; ii) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); iii) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; iv) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; v) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in C4); this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question C4) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. Syntax: * Shell word splitting: see question C4). * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. Coprocesses are established by `coproc'; `|&' behaves like csh. Command line substitutions, globbing etc.: * Failure to match a globbing pattern causes an error (use NO_NOMATCH). * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but * in zsh. (GLOB_SUBST has been added to fix this.) The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) * $PSn do not do parameter substitution by default (use PROMPT_SUBST). Globbing does not allow ksh-style `pattern-lists'. Equivalents: ------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that ~ is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the ~ operator). As the `**' operator cannot be grouped (inside parentheses it is treated as *), this is the way to exclude some subdirectories from matching a `**'. Unquoted assignments do file expansion after `:'s (intended for PATHs). `integer' does not allow -i. Command execution: * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). $PATH is not searched for commands specified at invocation without -c. Aliases and functions: The order in which aliases and functions are defined is significant (function definitions with () expand aliases -- see question B3). Aliases and functions cannot be exported. There are no tracked aliases: command hashing replaces these. The use of aliases for key bindings is replaced by `bindkey'. * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). Traps and signals: Traps are not local to functions. TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). Editing: The options emacs, gmacs, trackall, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' become `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. `Trackall' is replaced by `hashcmds'. The `keyword' option does not exist and -k is instead interactivecomments. (`keyword' will not be in the next ksh release either.) Management of histories in multiple shells is different: the history list is not saved and restored after each command. \ does not escape editing chars (use ^V). Not all ksh bindings are set (e.g. `<ESC>#'; try <ESC>q). * # in an interactive shell is not treated as a comment by default. Built-in commands: Some built-ins (r, autoload, history, integer ...) were aliases in ksh. There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' `jobs' has no `-n' flag. `read' has no `-s' flag. In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' it is treated as an expression). Other idiosyncrasies: `select' always redisplays the list of selections on each loop. B2) Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in scripts/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: Logout, rehash, source, (un)limit built-in commands. *rc file for interactive shells. Directory stacks. Cshjunkie*, ignoreeof options. The CSH_NULL_GLOB option. >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) foreach ... loops; alternative syntax for other loops. Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'). $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... Escape sequences via % for prompts. Special array variables $PATH etc. are colon-separated, $path are arrays. !-type history (which may be turned off via `setopt nobanghist'). Arrays have csh-like features (see under B1)). B3) Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1. If the csh alias references "parameters" (\!:1 \!* etc.), then in zsh you need a function (referencing $1 $* etc.). Otherwise, you can use a zsh alias. 2. If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3. If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4. If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: a. convert all of them to zsh functions; or b. after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5. Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6. Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7. To begin a zsh alias with a - (dash, hyphen) character, use "alias --": csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8. Stay away from "alias -g" in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. B4) Similarities with tcsh: (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with bindkey -s (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. Bindkey -s allows limitless possibilities along these lines. B5) Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. B6) Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/shell/\ csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Section C: How to get various things to work C1) How do I turn off spelling correction/globbing for an individual command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' (you can have both nocorrect and nglob, if you like). C2) How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes *before* any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. C3) Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that's_ not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. C4) Why does `$var' where var="foo bar" not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. C5) Why do my autoloaded functions not autoload [the first time]? (Before version 3.0, autoloading in the Korn shell way was not allowed; this article is now a historical artefact and will eventually be removed. Note, however, that the old form of autoloading is still allowed and there are no plans to remove it.) When you put a shell function in an autoload directory (i.e. one mentioned in $FPATH), it should be written just as if it were a shell script. In other words, there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching '}' at the end. If you include those, then the first time you try to use the function, the _whole_ file is run --- in other words, zsh simply defines the function and does nothing else. As a concrete example, if you have a function which you would define on the command line as `xhead () { print -n "\033]2;$*\a"; }' and your have assigned `FPATH=~/fns', then your .zshrc should contain `autoload xhead' and the file ~/fns/xhead should contain only `print -n "\033]2;$*\a"'. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) C6) How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$[ ... ]' method will always display in decimal. C7) How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. C9) Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. C10) How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. C11) Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. C12) Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (Nohup is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. C13) How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. Section D: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. D1) What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing "CTRL-x g", which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the section I will discuss completion only. D2) What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see D4).) D3) How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type ^D to see all the possible completions. (That's assuming your at the end of the line, otherwise ^D will delete the next character and you have to use Esc-^D.) This can be changed by the following options, among others: - with nobeep set, that annoying beep goes away - with nolistbeep, beeping is only turned off for ambiguous completions - with autolist set, when the completion is ambiguous you get a list without having to type ^D - with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted - with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started - with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. D4) How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example 'p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say 'p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, 'p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in D2)), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the -f before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): i) multiple square brackets after a single condition give alternatives: for example, 's[foo][bar]' says apply the completion if the word begins with `foo' or `bar', ii) spaces between conditions mean both must match: for example, 'p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', iii) commas between conditions mean either can match: for example, 'c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. D5) And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question B1); note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. (According to POSIX, this is not a bug with `special' builtins.) `time' is ignored with builtins and can't be used with {...}. `set -x' (`setopt xtrace') still has a few glitches. The :q modifier doesn't split words and -q and -x don't work for variables. In vi mode, `u' can go past the original modification point. The singlelinezle option has problems with prompts containing escapes. The `r' command does not work inside $(...) or `...` expansions. `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. Note that a few recent changes introduce incompatibilities (these are not bugs): Changes since zsh 2.5: Signal traps established with the `trap' builtin are now called with the environment of the caller, instead of as a new function level, as in ksh. Traps established as functions (e.g. `TRAPINT() {...}') work as before. The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. On the other hand, `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. The `HISTCHARS' variable is now `histchars'. Currently both are tied together for compatibility. The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. Z2) Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so any suggestions, complaints, questions and matters for discussion should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. Z3) What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. Loadable module support (will be in 3.1 but much work still needs doing). Ksh compatibility could be improved. Option for glob qualifiers to follow perl syntax (now a traditional item). Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. `PATH=' should clear the PATH: it inserts `.'; use `unset PATH' or `path=()' for the time being. This is not really a bug as the . would be used internally in any case (cf. ksh). Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.mal.com/zsh/".
[I shall be away till 2.1.97 (that's second of January to US customers) so this is early -- pws] Archive-Name: unix-faq/shell/zsh Last-Modified: 1996/12/19 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zsh.FAQ,v 2.22 1996/12/19 09:52:11 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996 (see end of document) Changes since last issue: in A4) new version 3.0.2 in A5) update archive list, avoid product placement in C) reorder, putting the old favourite (word splitting) first in C2) added a couple of notes on noXXX. in Z1) added note that `$1=$2' doesn't work, plus workaround. This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question A5); if you want to know what to do with insoluble problems, go to Z2). Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Section A: Introducing zsh and how to install it A0) Sources of information A1) What is it? A2) What is it good at? A3) On what machines will it run? (Plus important compilation notes) A4) What's the latest version? A5) Where do I get it? A6) I don't have root access: how do I make zsh my login shell? Section B: How does zsh differ from...? B1) sh and ksh? B2) csh? B3) Why do my csh aliases not work? (Plus other alias pitfalls.) B4) tcsh? B5) bash? B6) Shouldn't zsh be more/less like ksh/(t)csh? Section C: How to get various things to work C1) Why does `$var' where var="foo bar" not do what I expect? C2) How do I turn off spelling correction/globbing for an individual command? C3) How do I get the meta key to work on my xterm? C4) Why does my terminal act funny in some way? C5) Why do my autoloaded functions not autoload [the first time]? C6) How does base arithmetic work? C7) How do I get a newline in my prompt? C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? C9) Why can't I bind \C-s and \C-q any more? C10) How do I execute command `foo' within function `foo'? C11) Why do history substitutions with single bangs do something funny? C12) Why does zsh kill off all my background jobs when I logout? C13) How do I list all my history entries? Section D: The mysteries of completion D1) What is completion? D2) What sorts of things can be completed? D3) How does zsh deal with ambiguous completions? D4) How do I get started with programmable completion? D5) And if programmable completion isn't good enough? Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Z2) Where do I report bugs, get more info / who's working on zsh? Z3) What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Section A: Introducing zsh and how to install it A0) Sources of information Information on zsh is now available via the World Wide Web. The URL is "http://www.mal.com/zsh/". The server provides this FAQ and much else (thanks to Mark Borges for this). The FAQ is at "http://www.mal.com/zsh/FAQ/". Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question A5). (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question Z2). A1) What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); it's compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question Z2). Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. A2) What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). Command line editing: programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), multi-line commands editable as a single buffer (even files!), variable editing (vared), command buffer stack, print text straight into the buffer for immediate editing (print -z), execution of unbound commands, menu completion, variable, editing function and option name completion, inline expansion of variables, history commands. Globbing --- extremely powerful, including: recursive globbing (cf. find), file attribute qualifiers (size, type, etc. also cf. find), full alternation and negation of patterns. Handling of multiple redirections (simpler than tee). Large number of options for tailoring. Path expansion (=foo -> /usr/bin/foo). Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). Named directories. Comprehensive integer arithmetic. Manipulation of arrays (including reverse subscripting). Spelling correction. A3) On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question Z2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question A5), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. A4) What's the latest version? Zsh 3.0.2 has now been relased. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of Z1). This is longer than usual due to enhanced sh, ksh and POSIX compatibility. Version 3.1.0 is under test and will be released shortly. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question Z1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. A5) Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Australia ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.prz.tu-berlin.de/pub/unix/shells/zsh Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.cso.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ (If you don't understand URL's, the first thing after the ftp:// is the hostname and the remainder after the / is the directory. You can supply these directly to a Web browser. If you're reading this with a recent Web browser, you may just have to click on them.) The latest full release is in zsh.tar.gz in these directories. Note that this is in gzip format: you will need GNU gzip from your nearest GNU archive to unpack it. The up-to-the-minute development version is in zsh-beta.tar.gz. There is also a version under RCS control which may be more suitable for source hackers. A6) I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the -l tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as '-zsh', you can link zsh to -zsh (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure -zsh is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Section B: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. B1) Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: i) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; ii) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); iii) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; iv) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; v) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in C1); this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question C1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. Syntax: * Shell word splitting: see question C1). * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. Coprocesses are established by `coproc'; `|&' behaves like csh. Command line substitutions, globbing etc.: * Failure to match a globbing pattern causes an error (use NO_NOMATCH). * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but * in zsh. (GLOB_SUBST has been added to fix this.) The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) * $PSn do not do parameter substitution by default (use PROMPT_SUBST). Globbing does not allow ksh-style `pattern-lists'. Equivalents: ------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that ~ is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the ~ operator). As the `**' operator cannot be grouped (inside parentheses it is treated as *), this is the way to exclude some subdirectories from matching a `**'. Unquoted assignments do file expansion after `:'s (intended for PATHs). `integer' does not allow -i. Command execution: * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). $PATH is not searched for commands specified at invocation without -c. Aliases and functions: The order in which aliases and functions are defined is significant (function definitions with () expand aliases -- see question B3). Aliases and functions cannot be exported. There are no tracked aliases: command hashing replaces these. The use of aliases for key bindings is replaced by `bindkey'. * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). Traps and signals: Traps are not local to functions. TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). Editing: The options emacs, gmacs, trackall, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' become `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. `Trackall' is replaced by `hashcmds'. The `keyword' option does not exist and -k is instead interactivecomments. (`keyword' will not be in the next ksh release either.) Management of histories in multiple shells is different: the history list is not saved and restored after each command. \ does not escape editing chars (use ^V). Not all ksh bindings are set (e.g. `<ESC>#'; try <ESC>q). * # in an interactive shell is not treated as a comment by default. Built-in commands: Some built-ins (r, autoload, history, integer ...) were aliases in ksh. There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' `jobs' has no `-n' flag. `read' has no `-s' flag. In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' it is treated as an expression). Other idiosyncrasies: `select' always redisplays the list of selections on each loop. B2) Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in scripts/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: Logout, rehash, source, (un)limit built-in commands. *rc file for interactive shells. Directory stacks. Cshjunkie*, ignoreeof options. The CSH_NULL_GLOB option. >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) foreach ... loops; alternative syntax for other loops. Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'). $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... Escape sequences via % for prompts. Special array variables $PATH etc. are colon-separated, $path are arrays. !-type history (which may be turned off via `setopt nobanghist'). Arrays have csh-like features (see under B1)). B3) Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1. If the csh alias references "parameters" (\!:1 \!* etc.), then in zsh you need a function (referencing $1 $* etc.). Otherwise, you can use a zsh alias. 2. If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3. If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4. If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: a. convert all of them to zsh functions; or b. after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5. Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6. Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7. To begin a zsh alias with a - (dash, hyphen) character, use "alias --": csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8. Stay away from "alias -g" in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. B4) Similarities with tcsh: (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with bindkey -s (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. Bindkey -s allows limitless possibilities along these lines. B5) Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. B6) Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/shell/\ csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Section C: How to get various things to work C1) Why does `$var' where var="foo bar" not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. C2) How do I turn off spelling correction/globbing for an individual command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' (you can have both nocorrect and noglob, if you like). Two notes: 1) a shell function won't work, the no... directives must be expanded before the rest of the command line is parsed 2) nocorrect must come earlier than noglob if both appear, since it is needed by the line editor, while noglob is only handled when the command is examined. C3) How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes *before* any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. C4) Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that's_ not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. C5) Why do my autoloaded functions not autoload [the first time]? (Before version 3.0, autoloading in the Korn shell way was not allowed; this article is now a historical artefact and will eventually be removed. Note, however, that the old form of autoloading is still allowed and there are no plans to remove it.) When you put a shell function in an autoload directory (i.e. one mentioned in $FPATH), it should be written just as if it were a shell script. In other words, there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching '}' at the end. If you include those, then the first time you try to use the function, the _whole_ file is run --- in other words, zsh simply defines the function and does nothing else. As a concrete example, if you have a function which you would define on the command line as `xhead () { print -n "\033]2;$*\a"; }' and your have assigned `FPATH=~/fns', then your .zshrc should contain `autoload xhead' and the file ~/fns/xhead should contain only `print -n "\033]2;$*\a"'. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) C6) How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$[ ... ]' method will always display in decimal. C7) How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. C8) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. C9) Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. C10) How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. C11) Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. C12) Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (Nohup is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. C13) How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. Section D: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. D1) What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing "CTRL-x g", which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the section I will discuss completion only. D2) What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see D4).) D3) How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type ^D to see all the possible completions. (That's assuming your at the end of the line, otherwise ^D will delete the next character and you have to use Esc-^D.) This can be changed by the following options, among others: - with nobeep set, that annoying beep goes away - with nolistbeep, beeping is only turned off for ambiguous completions - with autolist set, when the completion is ambiguous you get a list without having to type ^D - with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted - with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started - with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. D4) How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example 'p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say 'p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, 'p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in D2)), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the -f before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): i) multiple square brackets after a single condition give alternatives: for example, 's[foo][bar]' says apply the completion if the word begins with `foo' or `bar', ii) spaces between conditions mean both must match: for example, 'p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', iii) commas between conditions mean either can match: for example, 'c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. D5) And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question B1); note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. (According to POSIX, this is not a bug with `special' builtins.) `time' is ignored with builtins and can't be used with {...}. `set -x' (`setopt xtrace') still has a few glitches. The :q modifier doesn't split words and -q and -x don't work for variables. In vi mode, `u' can go past the original modification point. The singlelinezle option has problems with prompts containing escapes. The `r' command does not work inside $(...) or `...` expansions. `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. Note that a few recent changes introduce incompatibilities (these are not bugs): Changes since zsh 2.5: The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. Signal traps established with the `trap' builtin are now called with the environment of the caller, instead of as a new function level, as in ksh. Traps established as functions (e.g. `TRAPINT() {...}') work as before. The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. On the other hand, `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. The `HISTCHARS' variable is now `histchars'. Currently both are tied together for compatibility. The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. Z2) Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so any suggestions, complaints, questions and matters for discussion should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. Z3) What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. Loadable module support (will be in 3.1 but much work still needs doing). Ksh compatibility could be improved. Option for glob qualifiers to follow perl syntax (now a traditional item). Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.mal.com/zsh/". # Local Variables: # xref-1:(t 3279 49 0) # xref-2:(t 3330 26 1) # xref-3:(t 4822 15 2) # xref-4:(t 5730 23 3) # xref-5:(t 7201 33 4) # xref-6:(t 8463 29 5) # xref-7:(t 9612 22 6) # xref-8:(t 11414 63 7) # xref-9:(t 14065 40 8) # xref-10:(t 14256 31 9) # xref-11:(t 16824 20 10) # xref-12:(t 17309 6 11) # xref-13:(t 19025 1 12) # xref-14:(t 19118 12 13) # xref-15:(t 21657 25 14) # xref-16:(t 22340 10 15) # xref-17:(t 22953 35 16) # xref-18:(t 26738 38 17) # xref-19:(t 27268 27 18) # xref-20:(t 28201 26 19) # xref-21:(t 28702 47 20) # xref-22:(t 29943 45 21) # xref-23:(t 29990 61 22) # xref-24:(t 32588 77 23) # xref-25:(t 33499 50 24) # xref-26:(t 34376 47 25) # xref-27:(t 36140 65 26) # xref-28:(t 37468 34 27) # xref-29:(t 38114 40 28) # xref-30:(t 38480 40 29) # xref-31:(t 39062 76 30) # xref-32:(t 39411 44 31) # xref-33:(t 39980 58 32) # xref-34:(t 40329 71 33) # xref-35:(t 40704 64 34) # xref-36:(t 41529 42 35) # xref-37:(t 41704 39 36) # xref-38:(t 42081 23 37) # xref-39:(t 43106 42 38) # xref-40:(t 45470 49 39) # xref-41:(t 46818 54 40) # xref-42:(t 51767 53 41) # xref-43:(t 52485 29 42) # xref-44:(t 52516 78 43) # xref-45:(t 53719 17 44) # xref-46:(t 54850 33 45) # xref-47:(t 56581 65 46) # xref-48:(t 58224 39 47) # xref-49:(t 58554 28 48) # xref-50:(1243 12 (6)) # xref-51:(1319 3 (46)) # xref-52:(1458 10 (6)) # xref-53:(1508 3 (1)) # xref-54:(1535 3 (2)) # xref-55:(1551 3 (8)) # xref-56:(1575 3 (8)) # xref-57:(1645 3 (8)) # xref-58:(1676 3 (6)) # xref-59:(1699 3 (7)) # xref-60:(1764 10 (8)) # xref-61:(1805 3 (9)) # xref-62:(1821 3 (14)) # xref-63:(1830 3 (16)) # xref-64:(1868 26 (28)) # xref-65:(1896 3 (18)) # xref-66:(1906 3 (19)) # xref-67:(1916 3 (20)) # xref-68:(1965 10 (21)) # xref-69:(2011 3 (22)) # xref-70:(2073 3 (23)) # xref-71:(2151 3 (24)) # xref-72:(2202 3 (25)) # xref-73:(2250 3 (26)) # xref-74:(2316 3 (27)) # xref-75:(2351 3 (29)) # xref-76:(2392 3 (46)) # xref-77:(2469 3 (31)) # xref-78:(2514 4 (32)) # xref-79:(2573 4 (33)) # xref-80:(2645 4 (34)) # xref-81:(2710 4 (35)) # xref-82:(2754 10 (36)) # xref-83:(2794 3 (37)) # xref-84:(2818 3 (38)) # xref-85:(2861 3 (39)) # xref-86:(2911 3 (40)) # xref-87:(2966 3 (41)) # xref-88:(3021 10 (42)) # xref-89:(3051 3 (43)) # xref-90:(3130 3 (46)) # xref-91:(3196 3 (48)) # xref-92:(4556 3 (6)) # xref-93:(4815 3 (46)) # xref-94:(5451 11 (46)) # xref-95:(7833 15 (46)) # xref-96:(7985 3 (6)) # xref-97:(8776 17 (44)) # xref-98:(9311 18 (44)) # xref-99:(15831 3 (22)) # xref-100:(16625 12 (22)) # xref-101:(17291 12 (22)) # xref-102:(19923 12 (16)) # xref-103:(22945 3 (11)) # xref-104:(45458 7 (40)) # xref-105:(52762 12 (10)) # End:
Archive-Name: unix-faq/shell/zsh Last-Modified: 1997/01/24 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zsh.FAQ,v 2.23 1997/01/24 13:21:16 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996 (see end of document) Changes since last issue: B): note existence of `UNIX shell differences' posting B3): extra note about functions and aliases new C4): how to put the directory in the xterm title bar (entry long overdue, sorry) Z3): mention future zle changes This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question A5); if you want to know what to do with insoluble problems, go to Z2). Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Section A: Introducing zsh and how to install it A0) Sources of information A1) What is it? A2) What is it good at? A3) On what machines will it run? (Plus important compilation notes) A4) What's the latest version? A5) Where do I get it? A6) I don't have root access: how do I make zsh my login shell? Section B: How does zsh differ from...? B1) sh and ksh? B2) csh? B3) Why do my csh aliases not work? (Plus other alias pitfalls.) B4) tcsh? B5) bash? B6) Shouldn't zsh be more/less like ksh/(t)csh? Section C: How to get various things to work C1) Why does `$var' where var="foo bar" not do what I expect? C2) How do I turn off spelling correction/globbing for an individual command? C3) How do I get the meta key to work on my xterm? C4) How do I automatically display the directory in my xterm title bar? C5) Why does my terminal act funny in some way? C6) Why do my autoloaded functions not autoload [the first time]? C7) How does base arithmetic work? C8) How do I get a newline in my prompt? C9) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? C10) Why can't I bind \C-s and \C-q any more? C11) How do I execute command `foo' within function `foo'? C12) Why do history substitutions with single bangs do something funny? C13) Why does zsh kill off all my background jobs when I logout? C14) How do I list all my history entries? Section D: The mysteries of completion D1) What is completion? D2) What sorts of things can be completed? D3) How does zsh deal with ambiguous completions? D4) How do I get started with programmable completion? D5) And if programmable completion isn't good enough? Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Z2) Where do I report bugs, get more info / who's working on zsh? Z3) What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Section A: Introducing zsh and how to install it A0) Sources of information Information on zsh is now available via the World Wide Web. The URL is "http://www.mal.com/zsh/". The server provides this FAQ and much else (thanks to Mark Borges for this). The FAQ is at "http://www.mal.com/zsh/FAQ/". Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question A5). (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question Z2). A1) What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); it's compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question Z2). Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. A2) What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). Command line editing: programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), multi-line commands editable as a single buffer (even files!), variable editing (vared), command buffer stack, print text straight into the buffer for immediate editing (print -z), execution of unbound commands, menu completion, variable, editing function and option name completion, inline expansion of variables, history commands. Globbing --- extremely powerful, including: recursive globbing (cf. find), file attribute qualifiers (size, type, etc. also cf. find), full alternation and negation of patterns. Handling of multiple redirections (simpler than tee). Large number of options for tailoring. Path expansion (=foo -> /usr/bin/foo). Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). Named directories. Comprehensive integer arithmetic. Manipulation of arrays (including reverse subscripting). Spelling correction. A3) On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question Z2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question A5), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. A4) What's the latest version? Zsh 3.0.2 has now been relased. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of Z1). This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.0 has also been released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question Z1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. A5) Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Australia ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ (If you don't understand URL's, the first thing after the ftp:// is the hostname and the remainder after the / is the directory. You can supply these directly to a Web browser. If you're reading this with a recent Web browser, you may just have to click on them.) The latest full release is in zsh.tar.gz in these directories. Note that this is in gzip format: you will need GNU gzip from your nearest GNU archive to unpack it. The up-to-the-minute development version is in zsh-beta.tar.gz. There is also a version under RCS control which may be more suitable for source hackers. A6) I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the -l tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as '-zsh', you can link zsh to -zsh (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure -zsh is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Section B: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET goupr comp.unix.shell. B1) Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: i) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; ii) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); iii) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; iv) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; v) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in C1); this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question C1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. Syntax: * Shell word splitting: see question C1). * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. Coprocesses are established by `coproc'; `|&' behaves like csh. Command line substitutions, globbing etc.: * Failure to match a globbing pattern causes an error (use NO_NOMATCH). * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but * in zsh. (GLOB_SUBST has been added to fix this.) The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) * $PSn do not do parameter substitution by default (use PROMPT_SUBST). Globbing does not allow ksh-style `pattern-lists'. Equivalents: ------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that ~ is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the ~ operator). As the `**' operator cannot be grouped (inside parentheses it is treated as *), this is the way to exclude some subdirectories from matching a `**'. Unquoted assignments do file expansion after `:'s (intended for PATHs). `integer' does not allow -i. Command execution: * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). $PATH is not searched for commands specified at invocation without -c. Aliases and functions: The order in which aliases and functions are defined is significant (function definitions with () expand aliases -- see question B3). Aliases and functions cannot be exported. There are no tracked aliases: command hashing replaces these. The use of aliases for key bindings is replaced by `bindkey'. * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). Traps and signals: Traps are not local to functions. TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). Editing: The options emacs, gmacs, trackall, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' become `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. `Trackall' is replaced by `hashcmds'. The `keyword' option does not exist and -k is instead interactivecomments. (`keyword' will not be in the next ksh release either.) Management of histories in multiple shells is different: the history list is not saved and restored after each command. \ does not escape editing chars (use ^V). Not all ksh bindings are set (e.g. `<ESC>#'; try <ESC>q). * # in an interactive shell is not treated as a comment by default. Built-in commands: Some built-ins (r, autoload, history, integer ...) were aliases in ksh. There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' `jobs' has no `-n' flag. `read' has no `-s' flag. In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' it is treated as an expression). Other idiosyncrasies: `select' always redisplays the list of selections on each loop. B2) Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in scripts/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: Logout, rehash, source, (un)limit built-in commands. *rc file for interactive shells. Directory stacks. Cshjunkie*, ignoreeof options. The CSH_NULL_GLOB option. >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) foreach ... loops; alternative syntax for other loops. Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'). $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... Escape sequences via % for prompts. Special array variables $PATH etc. are colon-separated, $path are arrays. !-type history (which may be turned off via `setopt nobanghist'). Arrays have csh-like features (see under B1)). B3) Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1. If the csh alias references "parameters" (\!:1 \!* etc.), then in zsh you need a function (referencing $1 $* etc.). Otherwise, you can use a zsh alias. 2. If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3. If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4. If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: a. convert all of them to zsh functions; or b. after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5. Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6. Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7. To begin a zsh alias with a - (dash, hyphen) character, use "alias --": csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8. Stay away from "alias -g" in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. B4) Similarities with tcsh: (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with bindkey -s (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. Bindkey -s allows limitless possibilities along these lines. B5) Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. B6) Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/shell/\ csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Section C: How to get various things to work C1) Why does `$var' where var="foo bar" not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. C2) How do I turn off spelling correction/globbing for an individual command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' (you can have both nocorrect and noglob, if you like). Two notes: 1) a shell function won't work, the no... directives must be expanded before the rest of the command line is parsed 2) nocorrect must come earlier than noglob if both appear, since it is needed by the line editor, while noglob is only handled when the command is examined. C3) How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes *before* any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. C4) How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option to print causes this to be interpreted as the current directory.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. C5) Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that's_ not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. C6) Why do my autoloaded functions not autoload [the first time]? (Before version 3.0, autoloading in the Korn shell way was not allowed; this article is now a historical artefact and will eventually be removed. Note, however, that the old form of autoloading is still allowed and there are no plans to remove it.) When you put a shell function in an autoload directory (i.e. one mentioned in $FPATH), it should be written just as if it were a shell script. In other words, there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching '}' at the end. If you include those, then the first time you try to use the function, the _whole_ file is run --- in other words, zsh simply defines the function and does nothing else. As a concrete example, if you have a function which you would define on the command line as `xhead () { print -n "\033]2;$*\a"; }' and your have assigned `FPATH=~/fns', then your .zshrc should contain `autoload xhead' and the file ~/fns/xhead should contain only `print -n "\033]2;$*\a"'. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) C7) How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$[ ... ]' method will always display in decimal. C8) How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. C9) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. C10) Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. C11) How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. C12) Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. C13) Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (Nohup is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. C14) How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. Section D: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. D1) What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing "CTRL-x g", which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the section I will discuss completion only. D2) What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see D4).) D3) How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type ^D to see all the possible completions. (That's assuming your at the end of the line, otherwise ^D will delete the next character and you have to use Esc-^D.) This can be changed by the following options, among others: - with nobeep set, that annoying beep goes away - with nolistbeep, beeping is only turned off for ambiguous completions - with autolist set, when the completion is ambiguous you get a list without having to type ^D - with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted - with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started - with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. D4) How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example 'p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say 'p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, 'p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in D2)), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the -f before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): i) multiple square brackets after a single condition give alternatives: for example, 's[foo][bar]' says apply the completion if the word begins with `foo' or `bar', ii) spaces between conditions mean both must match: for example, 'p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', iii) commas between conditions mean either can match: for example, 'c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. D5) And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question B1); note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. (According to POSIX, this is not a bug with `special' builtins.) `time' is ignored with builtins and can't be used with {...}. `set -x' (`setopt xtrace') still has a few glitches. The :q modifier doesn't split words and -q and -x don't work for variables. In vi mode, `u' can go past the original modification point. The singlelinezle option has problems with prompts containing escapes. The `r' command does not work inside $(...) or `...` expansions. `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. Note that a few recent changes introduce incompatibilities (these are not bugs): Changes since zsh 2.5: The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. Signal traps established with the `trap' builtin are now called with the environment of the caller, instead of as a new function level, as in ksh. Traps established as functions (e.g. `TRAPINT() {...}') work as before. The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. On the other hand, `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. The `HISTCHARS' variable is now `histchars'. Currently both are tied together for compatibility. The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. Z2) Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so any suggestions, complaints, questions and matters for discussion should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. Z3) What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. Loadable module support (will be in 3.1 but much work still needs doing). Ksh compatibility could be improved. Option for glob qualifiers to follow perl syntax (now a traditional item). Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.mal.com/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1997/02/25 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zsh.FAQ,v 2.24 1997/02/25 10:45:30 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996 (see end of document) Changes since last issue: in Z1) zle changes between 3.0 and 3.1: history-search-{forward,backward} and cursor bindings in vi insert mode (not). This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question A5); if you want to know what to do with insoluble problems, go to Z2). Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Section A: Introducing zsh and how to install it A0) Sources of information A1) What is it? A2) What is it good at? A3) On what machines will it run? (Plus important compilation notes) A4) What's the latest version? A5) Where do I get it? A6) I don't have root access: how do I make zsh my login shell? Section B: How does zsh differ from...? B1) sh and ksh? B2) csh? B3) Why do my csh aliases not work? (Plus other alias pitfalls.) B4) tcsh? B5) bash? B6) Shouldn't zsh be more/less like ksh/(t)csh? Section C: How to get various things to work C1) Why does `$var' where var="foo bar" not do what I expect? C2) How do I turn off spelling correction/globbing for an individual command? C3) How do I get the meta key to work on my xterm? C4) How do I automatically display the directory in my xterm title bar? C5) Why does my terminal act funny in some way? C6) Why do my autoloaded functions not autoload [the first time]? C7) How does base arithmetic work? C8) How do I get a newline in my prompt? C9) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? C10) Why can't I bind \C-s and \C-q any more? C11) How do I execute command `foo' within function `foo'? C12) Why do history substitutions with single bangs do something funny? C13) Why does zsh kill off all my background jobs when I logout? C14) How do I list all my history entries? Section D: The mysteries of completion D1) What is completion? D2) What sorts of things can be completed? D3) How does zsh deal with ambiguous completions? D4) How do I get started with programmable completion? D5) And if programmable completion isn't good enough? Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Z2) Where do I report bugs, get more info / who's working on zsh? Z3) What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Section A: Introducing zsh and how to install it A0) Sources of information Information on zsh is now available via the World Wide Web. The URL is "http://www.mal.com/zsh/". The server provides this FAQ and much else (thanks to Mark Borges for this). The FAQ is at "http://www.mal.com/zsh/FAQ/". Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question A5). (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question Z2). A1) What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); it's compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question Z2). Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. A2) What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). Command line editing: programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), multi-line commands editable as a single buffer (even files!), variable editing (vared), command buffer stack, print text straight into the buffer for immediate editing (print -z), execution of unbound commands, menu completion, variable, editing function and option name completion, inline expansion of variables, history commands. Globbing --- extremely powerful, including: recursive globbing (cf. find), file attribute qualifiers (size, type, etc. also cf. find), full alternation and negation of patterns. Handling of multiple redirections (simpler than tee). Large number of options for tailoring. Path expansion (=foo -> /usr/bin/foo). Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). Named directories. Comprehensive integer arithmetic. Manipulation of arrays (including reverse subscripting). Spelling correction. A3) On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question Z2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question A5), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. A4) What's the latest version? Zsh 3.0.2 has now been relased. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of Z1). This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.0 has also been released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question Z1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. A5) Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Australia ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ (If you don't understand URL's, the first thing after the ftp:// is the hostname and the remainder after the / is the directory. You can supply these directly to a Web browser. If you're reading this with a recent Web browser, you may just have to click on them.) The latest full release is in zsh.tar.gz in these directories. Note that this is in gzip format: you will need GNU gzip from your nearest GNU archive to unpack it. The up-to-the-minute development version is in zsh-beta.tar.gz. There is also a version under RCS control which may be more suitable for source hackers. A6) I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the -l tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as '-zsh', you can link zsh to -zsh (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure -zsh is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Section B: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET goupr comp.unix.shell. B1) Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: i) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; ii) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); iii) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; iv) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; v) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in C1); this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question C1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. Syntax: * Shell word splitting: see question C1). * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. Coprocesses are established by `coproc'; `|&' behaves like csh. Command line substitutions, globbing etc.: * Failure to match a globbing pattern causes an error (use NO_NOMATCH). * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but * in zsh. (GLOB_SUBST has been added to fix this.) The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) * $PSn do not do parameter substitution by default (use PROMPT_SUBST). Globbing does not allow ksh-style `pattern-lists'. Equivalents: ------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that ~ is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the ~ operator). As the `**' operator cannot be grouped (inside parentheses it is treated as *), this is the way to exclude some subdirectories from matching a `**'. Unquoted assignments do file expansion after `:'s (intended for PATHs). `integer' does not allow -i. Command execution: * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). $PATH is not searched for commands specified at invocation without -c. Aliases and functions: The order in which aliases and functions are defined is significant (function definitions with () expand aliases -- see question B3). Aliases and functions cannot be exported. There are no tracked aliases: command hashing replaces these. The use of aliases for key bindings is replaced by `bindkey'. * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). Traps and signals: Traps are not local to functions. TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). Editing: The options emacs, gmacs, trackall, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' become `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. `Trackall' is replaced by `hashcmds'. The `keyword' option does not exist and -k is instead interactivecomments. (`keyword' will not be in the next ksh release either.) Management of histories in multiple shells is different: the history list is not saved and restored after each command. \ does not escape editing chars (use ^V). Not all ksh bindings are set (e.g. `<ESC>#'; try <ESC>q). * # in an interactive shell is not treated as a comment by default. Built-in commands: Some built-ins (r, autoload, history, integer ...) were aliases in ksh. There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' `jobs' has no `-n' flag. `read' has no `-s' flag. In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' it is treated as an expression). Other idiosyncrasies: `select' always redisplays the list of selections on each loop. B2) Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in scripts/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: Logout, rehash, source, (un)limit built-in commands. *rc file for interactive shells. Directory stacks. Cshjunkie*, ignoreeof options. The CSH_NULL_GLOB option. >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) foreach ... loops; alternative syntax for other loops. Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'). $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... Escape sequences via % for prompts. Special array variables $PATH etc. are colon-separated, $path are arrays. !-type history (which may be turned off via `setopt nobanghist'). Arrays have csh-like features (see under B1)). B3) Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1. If the csh alias references "parameters" (\!:1 \!* etc.), then in zsh you need a function (referencing $1 $* etc.). Otherwise, you can use a zsh alias. 2. If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3. If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4. If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: a. convert all of them to zsh functions; or b. after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5. Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6. Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7. To begin a zsh alias with a - (dash, hyphen) character, use "alias --": csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8. Stay away from "alias -g" in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. B4) Similarities with tcsh: (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with bindkey -s (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. Bindkey -s allows limitless possibilities along these lines. B5) Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. B6) Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/shell/\ csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Section C: How to get various things to work C1) Why does `$var' where var="foo bar" not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. C2) How do I turn off spelling correction/globbing for an individual command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' (you can have both nocorrect and noglob, if you like). Two notes: 1) a shell function won't work, the no... directives must be expanded before the rest of the command line is parsed 2) nocorrect must come earlier than noglob if both appear, since it is needed by the line editor, while noglob is only handled when the command is examined. C3) How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes *before* any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. C4) How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the ~ notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. C5) Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that's_ not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. C6) Why do my autoloaded functions not autoload [the first time]? (Before version 3.0, autoloading in the Korn shell way was not allowed; this article is now a historical artefact and will eventually be removed. Note, however, that the old form of autoloading is still allowed and there are no plans to remove it.) When you put a shell function in an autoload directory (i.e. one mentioned in $FPATH), it should be written just as if it were a shell script. In other words, there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching '}' at the end. If you include those, then the first time you try to use the function, the _whole_ file is run --- in other words, zsh simply defines the function and does nothing else. As a concrete example, if you have a function which you would define on the command line as `xhead () { print -n "\033]2;$*\a"; }' and your have assigned `FPATH=~/fns', then your .zshrc should contain `autoload xhead' and the file ~/fns/xhead should contain only `print -n "\033]2;$*\a"'. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) C7) How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$[ ... ]' method will always display in decimal. C8) How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. C9) Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. C10) Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. C11) How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. C12) Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. C13) Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (Nohup is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. C14) How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. Section D: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. D1) What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing "CTRL-x g", which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the section I will discuss completion only. D2) What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see D4).) D3) How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type ^D to see all the possible completions. (That's assuming your at the end of the line, otherwise ^D will delete the next character and you have to use Esc-^D.) This can be changed by the following options, among others: - with nobeep set, that annoying beep goes away - with nolistbeep, beeping is only turned off for ambiguous completions - with autolist set, when the completion is ambiguous you get a list without having to type ^D - with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted - with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started - with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. D4) How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example 'p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say 'p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, 'p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in D2)), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the -f before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): i) multiple square brackets after a single condition give alternatives: for example, 's[foo][bar]' says apply the completion if the word begins with `foo' or `bar', ii) spaces between conditions mean both must match: for example, 'p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', iii) commas between conditions mean either can match: for example, 'c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. D5) And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Section Z: The future of zsh Z1) What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question B1); note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. (According to POSIX, this is not a bug with `special' builtins.) `time' is ignored with builtins and can't be used with {...}. `set -x' (`setopt xtrace') still has a few glitches. The :q and :x modifiers don't work for variables. In vi mode, `u' can go past the original modification point. The singlelinezle option has problems with prompts containing escapes. The `r' command does not work inside $(...) or `...` expansions. `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): history-search-{forward,backward} (bound to M-n, M-p) now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For an approximation to the old behaviour, use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. Signal traps established with the `trap' builtin are now called with the environment of the caller, instead of as a new function level, as in ksh. Traps established as functions (e.g. `TRAPINT() {...}') work as before. The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. On the other hand, `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. The `HISTCHARS' variable is now `histchars'. Currently both are tied together for compatibility. The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. Z2) Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so any suggestions, complaints, questions and matters for discussion should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. Z3) What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. Loadable module support (will be in 3.1 but much work still needs doing). Ksh compatibility could be improved. Option for glob qualifiers to follow perl syntax (now a traditional item). Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.mal.com/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1997/03/24 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.4 1997/03/24 08:44:15 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996 (see end of document) Changes since last issue: General: Converted to YODL format to make HTML and LaTeX as well as text versions available. 2.4: Expanded note on running commands in the middle of editing lines. New 3.6: Why does zsh not work in an Emacs shell mode any more? New 3.16: How does the alternative loop syntax, e.g. `while {...} {...}' work? This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. How do I turn off spelling correction/globbing for a single command? 3.3. How do I get the meta key to work on my xterm? 3.4. How do I automatically display the directory in my xterm title bar? 3.5. Why does my terminal act funny in some way? 3.6. Why does zsh not work in an Emacs shell mode any more? 3.7. Why do my autoloaded functions not autoload [the first time]? 3.8. How does base arithmetic work? 3.9. How do I get a newline in my prompt? 3.10. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.11. Why can't I bind \C-s and \C-q any more? 3.12. How do I execute command `foo' within function `foo'? 3.13. Why do history substitutions with single bangs do something funny? 3.14. Why does zsh kill off all my background jobs when I logout? 3.15. How do I list all my history entries? 3.16. How does the alternative loop syntax, e.g. `while {...} {...}' work? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I get started with programmable completion? 4.5. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is now available via the World Wide Web. The URL is http://www.mal.com/zsh/ . The server provides this FAQ and much else (thanks to Mark Borges for this). The FAQ is at http://www.mal.com/zsh/FAQ/ . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); it's compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2. Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.2 has now been released. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.0 has also been released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Australia ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o Globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' +it is treated as an expression). o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.3: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.4: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.5: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.6: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.7: Why do my autoloaded functions not autoload [the first time]? (Before version 3.0, autoloading in the Korn shell way was not allowed; this article is now a historical artefact and will eventually be removed. Note, however, that the old form of autoloading is still allowed and there are no plans to remove it.) When you put a shell function in an autoload directory (i.e. one mentioned in $FPATH), it should be written just as if it were a shell script. In other words, there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. If you include those, then the first time you try to use the function, the _whole_ file is run --- in other words, zsh simply defines the function and does nothing else. As a concrete example, if you have a function which you would define on the command line as `xhead () { print -n "\033]2;$*\a"; }' and your have assigned `FPATH=~/fns', then your .zshrc should contain `autoload xhead' and the file ~/fns/xhead should contain only `print -n "\033]2;$*\a"'. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.8: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.9: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.10: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.11: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. 3.12: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.13: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.14: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. 3.15: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.16: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.4.) 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. 4.4: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.5: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. (According to POSIX, this is not a bug with `special' builtins.) o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o The `:q' and `:x' modifiers don't work for variables. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o history-search-{forward,backward} (bound to \M-n, \M-p) now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For an approximation to the old behaviour, use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, instead of as a new function level, as in ksh. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o On the other hand, `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so any suggestions, complaints, questions and matters for discussion should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (now a traditional item). o Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. o Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.mal.com/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1997/04/24 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.5 1997/04/24 10:19:15 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996 (see end of document) Changes since last issue: 1.1: New WWW site (at www.peak.org). 3.2: New item on ALL_EXPORT option. This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. Why does my terminal act funny in some way? 3.7. Why does zsh not work in an Emacs shell mode any more? 3.9. Why do my autoloaded functions not autoload [the first time]? 3.9. How does base arithmetic work? 3.10. How do I get a newline in my prompt? 3.11. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.12. Why can't I bind \C-s and \C-q any more? 3.13. How do I execute command `foo' within function `foo'? 3.14. Why do history substitutions with single bangs do something funny? 3.15. Why does zsh kill off all my background jobs when I logout? 3.16. How do I list all my history entries? 3.17. How does the alternative loop syntax, e.g. `while {...} {...}' work? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I get started with programmable completion? 4.5. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://www.peak.org/zsh/ (note the change of address from the end of April 1997). The server provides this FAQ and much else (thanks to Mark Borges for this). The FAQ is at http://www.peak.org/zsh/FAQ/ . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); it's compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2. Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.2 has now been released. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.0 has also been released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Australia ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o Globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' +it is treated as an expression). o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.7: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.8: Why do my autoloaded functions not autoload [the first time]? (Before version 3.0, autoloading in the Korn shell way was not allowed; this article is now a historical artefact and will eventually be removed. Note, however, that the old form of autoloading is still allowed and there are no plans to remove it.) When you put a shell function in an autoload directory (i.e. one mentioned in $FPATH), it should be written just as if it were a shell script. In other words, there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. If you include those, then the first time you try to use the function, the _whole_ file is run --- in other words, zsh simply defines the function and does nothing else. As a concrete example, if you have a function which you would define on the command line as `xhead () { print -n "\033]2;$*\a"; }' and your have assigned `FPATH=~/fns', then your .zshrc should contain `autoload xhead' and the file ~/fns/xhead should contain only `print -n "\033]2;$*\a"'. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.9: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.10: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.11: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.12: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. 3.13: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.14: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.15: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. 3.16: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.17: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.4.) 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. 4.4: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.5: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. (According to POSIX, this is not a bug with `special' builtins.) o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o The `:q' and `:x' modifiers don't work for variables. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o history-search-{forward,backward} (bound to \M-n, \M-p) now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For an approximation to the old behaviour, use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, instead of as a new function level, as in ksh. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o On the other hand, `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so any suggestions, complaints, questions and matters for discussion should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (now a traditional item). o Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. o Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.peak.org/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1997/05/29 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.6 1997/05/29 09:15:00 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996 (see end of document) Changes since last issue: 1.5: Latest versions. 1.6: Mention test versions. This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. Why does my terminal act funny in some way? 3.7. Why does zsh not work in an Emacs shell mode any more? 3.9. Why do my autoloaded functions not autoload [the first time]? 3.9. How does base arithmetic work? 3.10. How do I get a newline in my prompt? 3.11. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.12. Why can't I bind \C-s and \C-q any more? 3.13. How do I execute command `foo' within function `foo'? 3.14. Why do history substitutions with single bangs do something funny? 3.15. Why does zsh kill off all my background jobs when I logout? 3.16. How do I list all my history entries? 3.17. How does the alternative loop syntax, e.g. `while {...} {...}' work? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I get started with programmable completion? 4.5. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://www.peak.org/zsh/ (note the change of address from the end of April 1997). The server provides this FAQ and much else and is now maintained by Timothy Lumoa. The FAQ is at http://www.peak.org/zsh/FAQ/ . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); it's compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2. Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.2 has now been released. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. Version 3.0.3 is currently in test. The beta version 3.1.1 has also been released; 3.1.2 is in test. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Australia ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o Globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' +it is treated as an expression). o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.7: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.8: Why do my autoloaded functions not autoload [the first time]? (Before version 3.0, autoloading in the Korn shell way was not allowed; this article is now a historical artefact and will eventually be removed. Note, however, that the old form of autoloading is still allowed and there are no plans to remove it.) When you put a shell function in an autoload directory (i.e. one mentioned in $FPATH), it should be written just as if it were a shell script. In other words, there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. If you include those, then the first time you try to use the function, the _whole_ file is run --- in other words, zsh simply defines the function and does nothing else. As a concrete example, if you have a function which you would define on the command line as `xhead () { print -n "\033]2;$*\a"; }' and your have assigned `FPATH=~/fns', then your .zshrc should contain `autoload xhead' and the file ~/fns/xhead should contain only `print -n "\033]2;$*\a"'. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.9: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.10: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.11: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.12: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. 3.13: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.14: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.15: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. 3.16: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.17: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.4.) 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. 4.4: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.5: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. (According to POSIX, this is not a bug with `special' builtins.) o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o The `:q' and `:x' modifiers don't work for variables. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o history-search-{forward,backward} (bound to \M-n, \M-p) now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For an approximation to the old behaviour, use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, instead of as a new function level, as in ksh. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o On the other hand, `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so any suggestions, complaints, questions and matters for discussion should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (now a traditional item). o Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. o Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.peak.org/zsh/".
[Note new question 3.6 on displaying eight bit characters in completion lists etc., comments welcome --- pws] Archive-Name: unix-faq/shell/zsh Last-Modified: 1997/06/25 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.7 1997/06/25 13:45:35 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996, 1997 (see end of document) Changes since last issue: 1.5: Latest versions. 3.6: New question on displaying eight bit characters. This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. How do I make the completion list use eight bit characters? 3.7. Why does my terminal act funny in some way? 3.8. Why does zsh not work in an Emacs shell mode any more? 3.9. Why do my autoloaded functions not autoload [the first time]? 3.10. How does base arithmetic work? 3.11. How do I get a newline in my prompt? 3.12. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.13. Why can't I bind \C-s and \C-q any more? 3.14. How do I execute command `foo' within function `foo'? 3.15. Why do history substitutions with single bangs do something funny? 3.16. Why does zsh kill off all my background jobs when I logout? 3.17. How do I list all my history entries? 3.18. How does the alternative loop syntax, e.g. `while {...} {...}' work? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I get started with programmable completion? 4.5. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://www.peak.org/zsh/ (note the change of address from the end of April 1997). The server provides this FAQ and much else and is now maintained by Timothy Luoma. The FAQ is at http://www.peak.org/zsh/FAQ/ . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); it's compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2. Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.4 has now been released. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.2 has also been released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Australia ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o Globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' +it is treated as an expression). o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: How do I make the completion list use eight bit characters? You are probably creating files with non-ASCII characters, such as accented characters, and find they show up in the completion list as \M-i or something such. This is because the library routines (not zsh itself) which test whether a character is printable have replied that it is not; zsh has simply found a way to show them anyway. The answer, under a modern POSIXy operating system, is to find a locale where these are treated as printable characters. Zsh has handling for locales built in and will recognise when you set a relevant variable. You need to look in /usr/lib/locale to find one which suits you; the subdirectories correspond to the locale names. The simplest possibility is likely to be en_US, so that the simplest answer to your problem is to set LC_CTYPE=en_US when your terminal is capable of showing eight bit characters. If you only have a default domain (called C), you may need to have some additional files installed on your system. 3.7: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.8: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.9: Why do my autoloaded functions not autoload [the first time]? (Before version 3.0, autoloading in the Korn shell way was not allowed; this article is now a historical artefact and will eventually be removed. Note, however, that the old form of autoloading is still allowed and there are no plans to remove it.) When you put a shell function in an autoload directory (i.e. one mentioned in $FPATH), it should be written just as if it were a shell script. In other words, there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. If you include those, then the first time you try to use the function, the _whole_ file is run --- in other words, zsh simply defines the function and does nothing else. As a concrete example, if you have a function which you would define on the command line as `xhead () { print -n "\033]2;$*\a"; }' and your have assigned `FPATH=~/fns', then your .zshrc should contain `autoload xhead' and the file ~/fns/xhead should contain only `print -n "\033]2;$*\a"'. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.10: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.11: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.12: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.13: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. 3.14: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.15: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.16: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. 3.17: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.18: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.4.) 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. 4.4: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.5: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. (According to POSIX, this is not a bug with `special' builtins.) o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o The `:q' and `:x' modifiers don't work for variables. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o history-search-{forward,backward} (bound to \M-n, \M-p) now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For an approximation to the old behaviour, use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, instead of as a new function level, as in ksh. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o On the other hand, `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so any suggestions, complaints, questions and matters for discussion should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (now a traditional item). o Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. o Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.peak.org/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1997/07/28 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.8 1997/07/28 09:58:28 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996, 1997 (see end of document) Changes since last issue: 1.5: Latest versions. 3.6: Rewritten to make clearer. 5.2: Improved description of zsh-workers list. This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. How do I make the completion list use eight bit characters? 3.7. Why does my terminal act funny in some way? 3.8. Why does zsh not work in an Emacs shell mode any more? 3.9. Why do my autoloaded functions not autoload [the first time]? 3.10. How does base arithmetic work? 3.11. How do I get a newline in my prompt? 3.12. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.13. Why can't I bind \C-s and \C-q any more? 3.14. How do I execute command `foo' within function `foo'? 3.15. Why do history substitutions with single bangs do something funny? 3.16. Why does zsh kill off all my background jobs when I logout? 3.17. How do I list all my history entries? 3.18. How does the alternative loop syntax, e.g. `while {...} {...}' work? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I get started with programmable completion? 4.5. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://www.peak.org/zsh/ (note the change of address from the end of April 1997). The server provides this FAQ and much else and is now maintained by Timothy Luoma. The FAQ is at http://www.peak.org/zsh/FAQ/ . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); it's compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2. Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.4 has now been released. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.2 has also been released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Australia ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o Globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' +it is treated as an expression). o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: How do I make the completion list use eight bit characters? A traditional UNIX environment (character terminal and ASCII character sets) is not sufficient to be able to handle non-ASCII characters, and there are so many possible enhancements that in general this is hard. However, if you have something like an xterm using a standard character set like ISO-8859-1 (which is often the default for xterm), read on. You should also note question 3.4 on the subject of eight bit characters. You are probably creating files with names including non-ASCII accented characters, and find they show up in the completion list as \M-i or something such. This is because the library routines (not zsh itself) which test whether a character is printable have replied that it is not; zsh has simply found a way to show them anyway. The answer, under a modern POSIXy operating system, is to find a locale where these are treated as printable characters. Zsh has handling for locales built in and will recognise when you set a relevant variable. You need to look in /usr/lib/locale to find one which suits you; the subdirectories correspond to the locale names. The simplest possibility is likely to be en_US, so that the simplest answer to your problem is to set LC_CTYPE=en_US when your terminal is capable of showing eight bit characters. If you only have a default domain (called C), you may need to have some additional files installed on your system. 3.7: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.8: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.9: Why do my autoloaded functions not autoload [the first time]? (Before version 3.0, autoloading in the Korn shell way was not allowed; this article is now a historical artefact and will eventually be removed. Note, however, that the old form of autoloading is still allowed and there are no plans to remove it.) When you put a shell function in an autoload directory (i.e. one mentioned in $FPATH), it should be written just as if it were a shell script. In other words, there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. If you include those, then the first time you try to use the function, the _whole_ file is run --- in other words, zsh simply defines the function and does nothing else. As a concrete example, if you have a function which you would define on the command line as `xhead () { print -n "\033]2;$*\a"; }' and your have assigned `FPATH=~/fns', then your .zshrc should contain `autoload xhead' and the file ~/fns/xhead should contain only `print -n "\033]2;$*\a"'. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.10: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.11: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.12: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.13: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. 3.14: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.15: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.16: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. 3.17: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.18: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.4.) 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. 4.4: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.5: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. (According to POSIX, this is not a bug with `special' builtins.) o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o The `:q' and `:x' modifiers don't work for variables. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o history-search-{forward,backward} (bound to \M-n, \M-p) now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For an approximation to the old behaviour, use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, instead of as a new function level, as in ksh. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o On the other hand, `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so mail on any issues (bug reports, suggestions, complaints...) related to the development of the shell should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (now a traditional item). o Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. o Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.peak.org/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1997/09/03 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.9 1997/09/03 08:07:18 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996, 1997 (see end of document) Changes since last issue: 1.4,1.6: Mention Windows and OS/2 versions 3.9: Rewrote explanation of autoload problems This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. How do I make the completion list use eight bit characters? 3.7. Why does my terminal act funny in some way? 3.8. Why does zsh not work in an Emacs shell mode any more? 3.9. Why do my autoloaded functions not autoload [the first time]? 3.10. How does base arithmetic work? 3.11. How do I get a newline in my prompt? 3.12. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.13. Why can't I bind \C-s and \C-q any more? 3.14. How do I execute command `foo' within function `foo'? 3.15. Why do history substitutions with single bangs do something funny? 3.16. Why does zsh kill off all my background jobs when I logout? 3.17. How do I list all my history entries? 3.18. How does the alternative loop syntax, e.g. `while {...} {...}' work? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I get started with programmable completion? 4.5. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://www.peak.org/zsh/ (note the change of address from the end of April 1997). The server provides this FAQ and much else and is now maintained by Timothy Luoma. The FAQ is at http://www.peak.org/zsh/FAQ/ . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); it's compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2. Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. There are also now separate ports for Windows and OS/2, see `Where do I get it' below. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.4 has now been released. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.2 has also been released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Australia ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ The Windows port mentioned above is maintained separately by Amol Deshpande <amol@microsoft.com>; please mail Amol directly about any Windows-specific problems. This is quite new, so don't expect it to be perfect. You can get it from: ftp://ftp.blarg.net/users/amol/zsh Likewise the OS/2 port is available from TAMURA Kent <kent@tril.ibm.co.jp at http://cgi.din.or.jp/~tkent/tmp/zsh-3.0.0-os2-a01.zip 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o Globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' +it is treated as an expression). o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: How do I make the completion list use eight bit characters? A traditional UNIX environment (character terminal and ASCII character sets) is not sufficient to be able to handle non-ASCII characters, and there are so many possible enhancements that in general this is hard. However, if you have something like an xterm using a standard character set like ISO-8859-1 (which is often the default for xterm), read on. You should also note question 3.4 on the subject of eight bit characters. You are probably creating files with names including non-ASCII accented characters, and find they show up in the completion list as \M-i or something such. This is because the library routines (not zsh itself) which test whether a character is printable have replied that it is not; zsh has simply found a way to show them anyway. The answer, under a modern POSIXy operating system, is to find a locale where these are treated as printable characters. Zsh has handling for locales built in and will recognise when you set a relevant variable. You need to look in /usr/lib/locale to find one which suits you; the subdirectories correspond to the locale names. The simplest possibility is likely to be en_US, so that the simplest answer to your problem is to set LC_CTYPE=en_US when your terminal is capable of showing eight bit characters. If you only have a default domain (called C), you may need to have some additional files installed on your system. 3.7: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.8: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.9: Why do my autoloaded functions not autoload [the first time]? The problem is that there are two possible ways of autoloading a function (see the AUTOLOADING FUNCTIONS section of the zsh manual page zshmisc for more detailed information): 1) The file contains just the body of the function, i.e. there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. This is the traditional zsh method. The advantage is that the file is called exactly like a script, so can double as both. To define a function `xhead () { print -n "\033]2;$*\a"; }', the file would just contain `print -n "\033]2;$*\a"'. 2) The file contains the entire definition, and maybe even other code: it is run when the function needs to be loaded, then the function itself is called up. This is the method in ksh. To define the same function `xhead', the whole of the usual definition should be in the file. In old versions of zsh, before 3.0, only the first behaviour was allowed, so you had to make sure the file found for autoload just contained the function body. You could still define other functions in the file with the standard form for definitions, though they would be redefined each time you called the main function. In version 3.0.x, the second behaviour is activated if the file defines the autoloaded function. Unfortunately, this is incompatible with the old zsh behaviour which allowed you to redefine the function when you called it. From version 3.1, there is an option KSHAUTOLOAD to allow full ksh compatiblity, i.e. the function _must_ be in the second form above. If that is not set, zsh tries to guess which form you are using: if the file contains only a complete definition of the function in the second form, and nothing else apart from comments and whitespace, it will use the function defined in the file; otherwise, it will assume the old behaviour. The option is set if `emulate ksh' is in effect, of course. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.10: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.11: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.12: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.13: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. 3.14: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.15: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.16: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. 3.17: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.18: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.4.) 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. 4.4: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.5: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o Special variables won't be unset after e.g. `PATH=... read ...', i.e. if used with a builtin command or shell function. (According to POSIX, this is not a bug with `special' builtins.) o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o The `:q' and `:x' modifiers don't work for variables. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o history-search-{forward,backward} (bound to \M-n, \M-p) now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For an approximation to the old behaviour, use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, instead of as a new function level, as in ksh. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o On the other hand, `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so mail on any issues (bug reports, suggestions, complaints...) related to the development of the shell should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (now a traditional item). o Binding of shell functions (or commands?) to key strokes -- requires some way of accessing the editing buffer from functions and probably of executing zle functions as a command. o Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.peak.org/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1997/09/25 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.10 1997/09/25 12:33:36 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996, 1997 (see end of document) Changes since last issue: 1.5: New 3.0.x version imminent 5.1: Delete `PATH=... builtin' bug Mention closure bug and fix 5.3: Mention zle development This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. How do I make the completion list use eight bit characters? 3.7. Why does my terminal act funny in some way? 3.8. Why does zsh not work in an Emacs shell mode any more? 3.9. Why do my autoloaded functions not autoload [the first time]? 3.10. How does base arithmetic work? 3.11. How do I get a newline in my prompt? 3.12. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.13. Why can't I bind \C-s and \C-q any more? 3.14. How do I execute command `foo' within function `foo'? 3.15. Why do history substitutions with single bangs do something funny? 3.16. Why does zsh kill off all my background jobs when I logout? 3.17. How do I list all my history entries? 3.18. How does the alternative loop syntax, e.g. `while {...} {...}' work? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I get started with programmable completion? 4.5. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://www.peak.org/zsh/ (note the change of address from the end of April 1997). The server provides this FAQ and much else and is now maintained by Timothy Luoma. The FAQ is at http://www.peak.org/zsh/FAQ/ . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); it's compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2. Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. There are also now separate ports for Windows and OS/2, see `Where do I get it' below. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.5 is in test and is expected to appear within days. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.2 has also been released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Australia ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ The Windows port mentioned above is maintained separately by Amol Deshpande <amold@microsoft.com>; please mail Amol directly about any Windows-specific problems. This is quite new, so don't expect it to be perfect. You can get it from: ftp://ftp.blarg.net/users/amol/zsh Likewise the OS/2 port is available from TAMURA Kent <kent@tril.ibm.co.jp at http://cgi.din.or.jp/~tkent/tmp/zsh-3.0.0-os2-a01.zip 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o Globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' +it is treated as an expression). o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: How do I make the completion list use eight bit characters? A traditional UNIX environment (character terminal and ASCII character sets) is not sufficient to be able to handle non-ASCII characters, and there are so many possible enhancements that in general this is hard. However, if you have something like an xterm using a standard character set like ISO-8859-1 (which is often the default for xterm), read on. You should also note question 3.4 on the subject of eight bit characters. You are probably creating files with names including non-ASCII accented characters, and find they show up in the completion list as \M-i or something such. This is because the library routines (not zsh itself) which test whether a character is printable have replied that it is not; zsh has simply found a way to show them anyway. The answer, under a modern POSIXy operating system, is to find a locale where these are treated as printable characters. Zsh has handling for locales built in and will recognise when you set a relevant variable. You need to look in /usr/lib/locale to find one which suits you; the subdirectories correspond to the locale names. The simplest possibility is likely to be en_US, so that the simplest answer to your problem is to set LC_CTYPE=en_US when your terminal is capable of showing eight bit characters. If you only have a default domain (called C), you may need to have some additional files installed on your system. 3.7: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.8: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.9: Why do my autoloaded functions not autoload [the first time]? The problem is that there are two possible ways of autoloading a function (see the AUTOLOADING FUNCTIONS section of the zsh manual page zshmisc for more detailed information): 1) The file contains just the body of the function, i.e. there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. This is the traditional zsh method. The advantage is that the file is called exactly like a script, so can double as both. To define a function `xhead () { print -n "\033]2;$*\a"; }', the file would just contain `print -n "\033]2;$*\a"'. 2) The file contains the entire definition, and maybe even other code: it is run when the function needs to be loaded, then the function itself is called up. This is the method in ksh. To define the same function `xhead', the whole of the usual definition should be in the file. In old versions of zsh, before 3.0, only the first behaviour was allowed, so you had to make sure the file found for autoload just contained the function body. You could still define other functions in the file with the standard form for definitions, though they would be redefined each time you called the main function. In version 3.0.x, the second behaviour is activated if the file defines the autoloaded function. Unfortunately, this is incompatible with the old zsh behaviour which allowed you to redefine the function when you called it. From version 3.1, there is an option KSHAUTOLOAD to allow full ksh compatiblity, i.e. the function _must_ be in the second form above. If that is not set, zsh tries to guess which form you are using: if the file contains only a complete definition of the function in the second form, and nothing else apart from comments and whitespace, it will use the function defined in the file; otherwise, it will assume the old behaviour. The option is set if `emulate ksh' is in effect, of course. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.10: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.11: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.12: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.13: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. 3.14: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.15: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.16: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. 3.17: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.18: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.4.) 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. 4.4: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.5: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o The `:q' and `:x' modifiers don't work for variables. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. o Nested closures in extended globbing and pattern matching, such as [[ fofo = (fo#)# ]] are not correctly handled (this will be fixed in version 3.1). Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o history-search-{forward,backward} (bound to \M-n, \M-p) now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For an approximation to the old behaviour, use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, instead of as a new function level, as in ksh. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o Mytt(foo=*) does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so mail on any issues (bug reports, suggestions, complaints...) related to the development of the shell should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (now a traditional item). o Binding of shell functions to key strokes, accessing editing buffer from functions, executing zle functions as a command: now under development for 3.1. o Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.peak.org/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1997/10/27 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.11 1997/10/27 16:07:02 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996, 1997 (see end of document) Changes since last issue: 1.6: New patch archive 2.1: Mention `cmd1 && cmd2 &' difference. 5.1: Mention $(r) bug fix This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. How do I make the completion list use eight bit characters? 3.7. Why does my terminal act funny in some way? 3.8. Why does zsh not work in an Emacs shell mode any more? 3.9. Why do my autoloaded functions not autoload [the first time]? 3.10. How does base arithmetic work? 3.11. How do I get a newline in my prompt? 3.12. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.13. Why can't I bind \C-s and \C-q any more? 3.14. How do I execute command `foo' within function `foo'? 3.15. Why do history substitutions with single bangs do something funny? 3.16. Why does zsh kill off all my background jobs when I logout? 3.17. How do I list all my history entries? 3.18. How does the alternative loop syntax, e.g. `while {...} {...}' work? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I get started with programmable completion? 4.5. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://www.peak.org/zsh/ (note the change of address from the end of April 1997). The server provides this FAQ and much else and is now maintained by Timothy Luoma. The FAQ is at http://www.peak.org/zsh/FAQ/ . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); it's compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2. Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. There are also now separate ports for Windows and OS/2, see `Where do I get it' below. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.5 is in test and is expected to appear within days. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.2 has also been released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Australia ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ The Windows port mentioned above is maintained separately by Amol Deshpande <amold@microsoft.com>; please mail Amol directly about any Windows-specific problems. This is quite new, so don't expect it to be perfect. You can get it from: ftp://ftp.blarg.net/users/amol/zsh Likewise the OS/2 port is available from TAMURA Kent <kent@tril.ibm.co.jp at http://cgi.din.or.jp/~tkent/tmp/zsh-3.0.0-os2-a01.zip Starting from mid-October 1997, there is an archive of patches sent to the maintainers' mailing list. Note that these may not all be added to the shell, and some may already have been; you simply have to search for something you might want which is not in the version you have. Also, there may be some prerequisites earlier in the archive. It can be found on the zsh WWW pages (as described in 1.1) at: http://www.peak.org/zsh/Patches/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. o In `cmd1 && cmd2 &', only `cmd2' instead of the whole expression is run in the background in zsh. The manual implies this is a bug. Use `{ cmd1 && cmd2 } &' as a workaround. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o Globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' +it is treated as an expression). o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: How do I make the completion list use eight bit characters? A traditional UNIX environment (character terminal and ASCII character sets) is not sufficient to be able to handle non-ASCII characters, and there are so many possible enhancements that in general this is hard. However, if you have something like an xterm using a standard character set like ISO-8859-1 (which is often the default for xterm), read on. You should also note question 3.4 on the subject of eight bit characters. You are probably creating files with names including non-ASCII accented characters, and find they show up in the completion list as \M-i or something such. This is because the library routines (not zsh itself) which test whether a character is printable have replied that it is not; zsh has simply found a way to show them anyway. The answer, under a modern POSIXy operating system, is to find a locale where these are treated as printable characters. Zsh has handling for locales built in and will recognise when you set a relevant variable. You need to look in /usr/lib/locale to find one which suits you; the subdirectories correspond to the locale names. The simplest possibility is likely to be en_US, so that the simplest answer to your problem is to set LC_CTYPE=en_US when your terminal is capable of showing eight bit characters. If you only have a default domain (called C), you may need to have some additional files installed on your system. 3.7: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.8: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.9: Why do my autoloaded functions not autoload [the first time]? The problem is that there are two possible ways of autoloading a function (see the AUTOLOADING FUNCTIONS section of the zsh manual page zshmisc for more detailed information): 1) The file contains just the body of the function, i.e. there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. This is the traditional zsh method. The advantage is that the file is called exactly like a script, so can double as both. To define a function `xhead () { print -n "\033]2;$*\a"; }', the file would just contain `print -n "\033]2;$*\a"'. 2) The file contains the entire definition, and maybe even other code: it is run when the function needs to be loaded, then the function itself is called up. This is the method in ksh. To define the same function `xhead', the whole of the usual definition should be in the file. In old versions of zsh, before 3.0, only the first behaviour was allowed, so you had to make sure the file found for autoload just contained the function body. You could still define other functions in the file with the standard form for definitions, though they would be redefined each time you called the main function. In version 3.0.x, the second behaviour is activated if the file defines the autoloaded function. Unfortunately, this is incompatible with the old zsh behaviour which allowed you to redefine the function when you called it. From version 3.1, there is an option KSHAUTOLOAD to allow full ksh compatiblity, i.e. the function _must_ be in the second form above. If that is not set, zsh tries to guess which form you are using: if the file contains only a complete definition of the function in the second form, and nothing else apart from comments and whitespace, it will use the function defined in the file; otherwise, it will assume the old behaviour. The option is set if `emulate ksh' is in effect, of course. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.10: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.11: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.12: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.13: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. 3.14: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.15: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.16: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. 3.17: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.18: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.4.) 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. 4.4: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.5: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. (A fix for this will appear shortly.) o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. o Nested closures in extended globbing and pattern matching, such as [[ fofo = (fo#)# ]] are not correctly handled (this will be fixed in version 3.1). Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o history-search-{forward,backward} (bound to \M-n, \M-p) now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For an approximation to the old behaviour, use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, as in ksh, instead of as a new function level. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o Mytt(foo=*) does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so mail on any issues (bug reports, suggestions, complaints...) related to the development of the shell should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (now a traditional item). o Binding of shell functions to key strokes, accessing editing buffer from functions, executing zle functions as a command: now under development for 3.1. o Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.peak.org/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1997/10/27 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.12 1997/11/25 08:42:40 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996, 1997 (see end of document) Changes since last issue: None This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. How do I make the completion list use eight bit characters? 3.7. Why does my terminal act funny in some way? 3.8. Why does zsh not work in an Emacs shell mode any more? 3.9. Why do my autoloaded functions not autoload [the first time]? 3.10. How does base arithmetic work? 3.11. How do I get a newline in my prompt? 3.12. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.13. Why can't I bind \C-s and \C-q any more? 3.14. How do I execute command `foo' within function `foo'? 3.15. Why do history substitutions with single bangs do something funny? 3.16. Why does zsh kill off all my background jobs when I logout? 3.17. How do I list all my history entries? 3.18. How does the alternative loop syntax, e.g. `while {...} {...}' work? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I get started with programmable completion? 4.5. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://www.peak.org/zsh/ (note the change of address from the end of April 1997). The server provides this FAQ and much else and is now maintained by Timothy Luoma. The FAQ is at http://www.peak.org/zsh/FAQ/ . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); it's compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2. Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. There are also now separate ports for Windows and OS/2, see `Where do I get it' below. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.5 is in test and is expected to appear within days. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.2 has also been released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Australia ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ The Windows port mentioned above is maintained separately by Amol Deshpande <amold@microsoft.com>; please mail Amol directly about any Windows-specific problems. This is quite new, so don't expect it to be perfect. You can get it from: ftp://ftp.blarg.net/users/amol/zsh Likewise the OS/2 port is available from TAMURA Kent <kent@tril.ibm.co.jp at http://cgi.din.or.jp/~tkent/tmp/zsh-3.0.0-os2-a01.zip Starting from mid-October 1997, there is an archive of patches sent to the maintainers' mailing list. Note that these may not all be added to the shell, and some may already have been; you simply have to search for something you might want which is not in the version you have. Also, there may be some prerequisites earlier in the archive. It can be found on the zsh WWW pages (as described in 1.1) at: http://www.peak.org/zsh/Patches/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. o In `cmd1 && cmd2 &', only `cmd2' instead of the whole expression is run in the background in zsh. The manual implies this is a bug. Use `{ cmd1 && cmd2 } &' as a workaround. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o Globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o In `let "i = foo"', foo is evaluated as a number, not an expression (although in `let "i = $foo"' +it is treated as an expression). o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: How do I make the completion list use eight bit characters? A traditional UNIX environment (character terminal and ASCII character sets) is not sufficient to be able to handle non-ASCII characters, and there are so many possible enhancements that in general this is hard. However, if you have something like an xterm using a standard character set like ISO-8859-1 (which is often the default for xterm), read on. You should also note question 3.4 on the subject of eight bit characters. You are probably creating files with names including non-ASCII accented characters, and find they show up in the completion list as \M-i or something such. This is because the library routines (not zsh itself) which test whether a character is printable have replied that it is not; zsh has simply found a way to show them anyway. The answer, under a modern POSIXy operating system, is to find a locale where these are treated as printable characters. Zsh has handling for locales built in and will recognise when you set a relevant variable. You need to look in /usr/lib/locale to find one which suits you; the subdirectories correspond to the locale names. The simplest possibility is likely to be en_US, so that the simplest answer to your problem is to set LC_CTYPE=en_US when your terminal is capable of showing eight bit characters. If you only have a default domain (called C), you may need to have some additional files installed on your system. 3.7: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.8: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.9: Why do my autoloaded functions not autoload [the first time]? The problem is that there are two possible ways of autoloading a function (see the AUTOLOADING FUNCTIONS section of the zsh manual page zshmisc for more detailed information): 1) The file contains just the body of the function, i.e. there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. This is the traditional zsh method. The advantage is that the file is called exactly like a script, so can double as both. To define a function `xhead () { print -n "\033]2;$*\a"; }', the file would just contain `print -n "\033]2;$*\a"'. 2) The file contains the entire definition, and maybe even other code: it is run when the function needs to be loaded, then the function itself is called up. This is the method in ksh. To define the same function `xhead', the whole of the usual definition should be in the file. In old versions of zsh, before 3.0, only the first behaviour was allowed, so you had to make sure the file found for autoload just contained the function body. You could still define other functions in the file with the standard form for definitions, though they would be redefined each time you called the main function. In version 3.0.x, the second behaviour is activated if the file defines the autoloaded function. Unfortunately, this is incompatible with the old zsh behaviour which allowed you to redefine the function when you called it. From version 3.1, there is an option KSHAUTOLOAD to allow full ksh compatiblity, i.e. the function _must_ be in the second form above. If that is not set, zsh tries to guess which form you are using: if the file contains only a complete definition of the function in the second form, and nothing else apart from comments and whitespace, it will use the function defined in the file; otherwise, it will assume the old behaviour. The option is set if `emulate ksh' is in effect, of course. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.10: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.11: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.12: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.13: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. 3.14: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.15: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.16: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. 3.17: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.18: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.4.) 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. 4.4: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.5: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. (A fix for this will appear shortly.) o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. o Nested closures in extended globbing and pattern matching, such as [[ fofo = (fo#)# ]] are not correctly handled (this will be fixed in version 3.1). Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o history-search-{forward,backward} (bound to \M-n, \M-p) now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For an approximation to the old behaviour, use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, as in ksh, instead of as a new function level. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o Mytt(foo=*) does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so mail on any issues (bug reports, suggestions, complaints...) related to the development of the shell should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (now a traditional item). o Binding of shell functions to key strokes, accessing editing buffer from functions, executing zle functions as a command: now under development for 3.1. o Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.peak.org/zsh/".
[This is early because I will be away for three weeks --- pws] Archive-Name: unix-faq/shell/zsh Last-Modified: 1997/12/19 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.13 1997/12/19 10:42:31 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996, 1997 (see end of document) Changes since last issue: 1.1: Mention new reference card (under development). 1.5: 3.0.5 has appeared (and had last time, too). This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. How do I make the completion list use eight bit characters? 3.7. Why does my terminal act funny in some way? 3.8. Why does zsh not work in an Emacs shell mode any more? 3.9. Why do my autoloaded functions not autoload [the first time]? 3.10. How does base arithmetic work? 3.11. How do I get a newline in my prompt? 3.12. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.13. Why can't I bind \C-s and \C-q any more? 3.14. How do I execute command `foo' within function `foo'? 3.15. Why do history substitutions with single bangs do something funny? 3.16. Why does zsh kill off all my background jobs when I logout? 3.17. How do I list all my history entries? 3.18. How does the alternative loop syntax, e.g. `while {...} {...}' work? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I get started with programmable completion? 4.5. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://www.peak.org/zsh/ (note the change of address from the end of April 1997). The server provides this FAQ and much else and is now maintained by Timothy Luoma. The FAQ is at http://www.peak.org/zsh/FAQ/ . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. There is now a preliminary version of a reference card for zsh 3.0, which you can find (while it's being developed) at http://www.ifh.de/~pws/computing/refcard.ps This is optimised for A4 paper. The LaTeX source is in the same place with the extension .tex. It is not a good place from which to learn zsh for the first time. (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); its compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2. Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. There are also now separate ports for Windows and OS/2, see `Where do I get it' below. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.5 is the latest production version. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.2 has also been released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Australia ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ The Windows port mentioned above is maintained separately by Amol Deshpande <amold@microsoft.com>; please mail Amol directly about any Windows-specific problems. This is quite new, so don't expect it to be perfect. You can get it from: ftp://ftp.blarg.net/users/amol/zsh Likewise the OS/2 port is available from TAMURA Kent <kent@tril.ibm.co.jp> at http://cgi.din.or.jp/~tkent/tmp/zsh-3.0.0-os2-a01.zip Starting from mid-October 1997, there is an archive of patches sent to the maintainers' mailing list. Note that these may not all be added to the shell, and some may already have been; you simply have to search for something you might want which is not in the version you have. Also, there may be some prerequisites earlier in the archive. It can be found on the zsh WWW pages (as described in 1.1) at: http://www.peak.org/zsh/Patches/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. o In `cmd1 && cmd2 &', only `cmd2' instead of the whole expression is run in the background in zsh. The manual implies this is a bug. Use `{ cmd1 && cmd2 } &' as a workaround. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o Globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o In `let "i = foo"', foo is evaluated as a number, not an expression (in `let "i = $foo"', however, it is treated as an expression). o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. The introduction of loadable in modules in version 3.1 should help. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: How do I make the completion list use eight bit characters? A traditional UNIX environment (character terminal and ASCII character sets) is not sufficient to be able to handle non-ASCII characters, and there are so many possible enhancements that in general this is hard. However, if you have something like an xterm using a standard character set like ISO-8859-1 (which is often the default for xterm), read on. You should also note question 3.4 on the subject of eight bit characters. You are probably creating files with names including non-ASCII accented characters, and find they show up in the completion list as \M-i or something such. This is because the library routines (not zsh itself) which test whether a character is printable have replied that it is not; zsh has simply found a way to show them anyway. The answer, under a modern POSIXy operating system, is to find a locale where these are treated as printable characters. Zsh has handling for locales built in and will recognise when you set a relevant variable. You need to look in /usr/lib/locale to find one which suits you; the subdirectories correspond to the locale names. The simplest possibility is likely to be en_US, so that the simplest answer to your problem is to set LC_CTYPE=en_US when your terminal is capable of showing eight bit characters. If you only have a default domain (called C), you may need to have some additional files installed on your system. 3.7: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.8: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.9: Why do my autoloaded functions not autoload [the first time]? The problem is that there are two possible ways of autoloading a function (see the AUTOLOADING FUNCTIONS section of the zsh manual page zshmisc for more detailed information): 1) The file contains just the body of the function, i.e. there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. This is the traditional zsh method. The advantage is that the file is called exactly like a script, so can double as both. To define a function `xhead () { print -n "\033]2;$*\a"; }', the file would just contain `print -n "\033]2;$*\a"'. 2) The file contains the entire definition, and maybe even other code: it is run when the function needs to be loaded, then the function itself is called up. This is the method in ksh. To define the same function `xhead', the whole of the usual definition should be in the file. In old versions of zsh, before 3.0, only the first behaviour was allowed, so you had to make sure the file found for autoload just contained the function body. You could still define other functions in the file with the standard form for definitions, though they would be redefined each time you called the main function. In version 3.0.x, the second behaviour is activated if the file defines the autoloaded function. Unfortunately, this is incompatible with the old zsh behaviour which allowed you to redefine the function when you called it. From version 3.1, there is an option KSHAUTOLOAD to allow full ksh compatiblity, i.e. the function _must_ be in the second form above. If that is not set, zsh tries to guess which form you are using: if the file contains only a complete definition of the function in the second form, and nothing else apart from comments and whitespace, it will use the function defined in the file; otherwise, it will assume the old behaviour. The option is set if `emulate ksh' is in effect, of course. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.10: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.11: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.12: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.13: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. 3.14: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.15: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.16: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. 3.17: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.18: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.4.) 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. 4.4: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.5: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. (A fix for this will appear shortly.) o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. o Nested closures in extended globbing and pattern matching, such as [[ fofo = (fo#)# ]] are not correctly handled (this will be fixed in version 3.1). Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o history-search-{forward,backward} (bound to \M-n, \M-p) now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For an approximation to the old behaviour, use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, as in ksh, instead of as a new function level. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o Mytt(foo=*) does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so mail on any issues (bug reports, suggestions, complaints...) related to the development of the shell should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (now a traditional item). o Binding of shell functions to key strokes, accessing editing buffer from functions, executing zle functions as a command: now under development for 3.1. o Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.peak.org/zsh/".
[ The FAQ doesn't mention zsh-3.1.2-zefram3 since that's not on the usual distribution network. If the current situation goes on I will eventually have to add it - pws] Archive-Name: unix-faq/shell/zsh Last-Modified: 1998/1/26 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.14 1998/01/26 09:01:19 pws Exp pws $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996, 1997, 1998 (see end of document) Changes since last issue: No changes (except this one, and the date of course). This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. How do I make the completion list use eight bit characters? 3.7. Why does my terminal act funny in some way? 3.8. Why does zsh not work in an Emacs shell mode any more? 3.9. Why do my autoloaded functions not autoload [the first time]? 3.10. How does base arithmetic work? 3.11. How do I get a newline in my prompt? 3.12. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.13. Why can't I bind \C-s and \C-q any more? 3.14. How do I execute command `foo' within function `foo'? 3.15. Why do history substitutions with single bangs do something funny? 3.16. Why does zsh kill off all my background jobs when I logout? 3.17. How do I list all my history entries? 3.18. How does the alternative loop syntax, e.g. `while {...} {...}' work? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I get started with programmable completion? 4.5. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://www.peak.org/zsh/ (note the change of address from the end of April 1997). The server provides this FAQ and much else and is now maintained by Timothy Luoma. The FAQ is at http://www.peak.org/zsh/FAQ/ . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. There is now a preliminary version of a reference card for zsh 3.0, which you can find (while it's being developed) at http://www.ifh.de/~pws/computing/refcard.ps This is optimised for A4 paper. The LaTeX source is in the same place with the extension .tex. It is not a good place from which to learn zsh for the first time. (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); its compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2. Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. There are also now separate ports for Windows and OS/2, see `Where do I get it' below. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.5 is the latest production version. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.2 has also been released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Australia ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ The Windows port mentioned above is maintained separately by Amol Deshpande <amold@microsoft.com>; please mail Amol directly about any Windows-specific problems. This is quite new, so don't expect it to be perfect. You can get it from: ftp://ftp.blarg.net/users/amol/zsh Likewise the OS/2 port is available from TAMURA Kent <kent@tril.ibm.co.jp> at http://cgi.din.or.jp/~tkent/tmp/zsh-3.0.0-os2-a01.zip Starting from mid-October 1997, there is an archive of patches sent to the maintainers' mailing list. Note that these may not all be added to the shell, and some may already have been; you simply have to search for something you might want which is not in the version you have. Also, there may be some prerequisites earlier in the archive. It can be found on the zsh WWW pages (as described in 1.1) at: http://www.peak.org/zsh/Patches/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. o In `cmd1 && cmd2 &', only `cmd2' instead of the whole expression is run in the background in zsh. The manual implies this is a bug. Use `{ cmd1 && cmd2 } &' as a workaround. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o Globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o In `let "i = foo"', foo is evaluated as a number, not an expression (in `let "i = $foo"', however, it is treated as an expression). o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. The introduction of loadable in modules in version 3.1 should help. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: How do I make the completion list use eight bit characters? A traditional UNIX environment (character terminal and ASCII character sets) is not sufficient to be able to handle non-ASCII characters, and there are so many possible enhancements that in general this is hard. However, if you have something like an xterm using a standard character set like ISO-8859-1 (which is often the default for xterm), read on. You should also note question 3.4 on the subject of eight bit characters. You are probably creating files with names including non-ASCII accented characters, and find they show up in the completion list as \M-i or something such. This is because the library routines (not zsh itself) which test whether a character is printable have replied that it is not; zsh has simply found a way to show them anyway. The answer, under a modern POSIXy operating system, is to find a locale where these are treated as printable characters. Zsh has handling for locales built in and will recognise when you set a relevant variable. You need to look in /usr/lib/locale to find one which suits you; the subdirectories correspond to the locale names. The simplest possibility is likely to be en_US, so that the simplest answer to your problem is to set LC_CTYPE=en_US when your terminal is capable of showing eight bit characters. If you only have a default domain (called C), you may need to have some additional files installed on your system. 3.7: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.8: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.9: Why do my autoloaded functions not autoload [the first time]? The problem is that there are two possible ways of autoloading a function (see the AUTOLOADING FUNCTIONS section of the zsh manual page zshmisc for more detailed information): 1) The file contains just the body of the function, i.e. there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. This is the traditional zsh method. The advantage is that the file is called exactly like a script, so can double as both. To define a function `xhead () { print -n "\033]2;$*\a"; }', the file would just contain `print -n "\033]2;$*\a"'. 2) The file contains the entire definition, and maybe even other code: it is run when the function needs to be loaded, then the function itself is called up. This is the method in ksh. To define the same function `xhead', the whole of the usual definition should be in the file. In old versions of zsh, before 3.0, only the first behaviour was allowed, so you had to make sure the file found for autoload just contained the function body. You could still define other functions in the file with the standard form for definitions, though they would be redefined each time you called the main function. In version 3.0.x, the second behaviour is activated if the file defines the autoloaded function. Unfortunately, this is incompatible with the old zsh behaviour which allowed you to redefine the function when you called it. From version 3.1, there is an option KSHAUTOLOAD to allow full ksh compatiblity, i.e. the function _must_ be in the second form above. If that is not set, zsh tries to guess which form you are using: if the file contains only a complete definition of the function in the second form, and nothing else apart from comments and whitespace, it will use the function defined in the file; otherwise, it will assume the old behaviour. The option is set if `emulate ksh' is in effect, of course. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.10: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.11: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.12: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.13: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. 3.14: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.15: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.16: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. 3.17: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.18: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.4.) 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. 4.4: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.5: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. (A fix for this will appear shortly.) o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. o Nested closures in extended globbing and pattern matching, such as [[ fofo = (fo#)# ]] are not correctly handled (this will be fixed in version 3.1). Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o history-search-{forward,backward} (bound to \M-n, \M-p) now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For an approximation to the old behaviour, use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, as in ksh, instead of as a new function level. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o Mytt(foo=*) does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so mail on any issues (bug reports, suggestions, complaints...) related to the development of the shell should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (now a traditional item). o Binding of shell functions to key strokes, accessing editing buffer from functions, executing zle functions as a command: now under development for 3.1. o Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.peak.org/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1998/3/2 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.15 1998/03/02 09:14:41 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996, 1997, 1998 (see end of document) Changes since last issue: 3.19 New: `why is my history not being saved?' This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. How do I make the completion list use eight bit characters? 3.7. Why does my terminal act funny in some way? 3.8. Why does zsh not work in an Emacs shell mode any more? 3.9. Why do my autoloaded functions not autoload [the first time]? 3.10. How does base arithmetic work? 3.11. How do I get a newline in my prompt? 3.12. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.13. Why can't I bind \C-s and \C-q any more? 3.14. How do I execute command `foo' within function `foo'? 3.15. Why do history substitutions with single bangs do something funny? 3.16. Why does zsh kill off all my background jobs when I logout? 3.17. How do I list all my history entries? 3.18. How does the alternative loop syntax, e.g. `while {...} {...}' work? 3.19. Why is my history not being saved? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I get started with programmable completion? 4.5. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://www.peak.org/zsh/ (note the change of address from the end of April 1997). The server provides this FAQ and much else and is now maintained by Timothy Luoma. The FAQ is at http://www.peak.org/zsh/FAQ/ . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. There is now a preliminary version of a reference card for zsh 3.0, which you can find (while it's being developed) at http://www.ifh.de/~pws/computing/refcard.ps This is optimised for A4 paper. The LaTeX source is in the same place with the extension .tex. It is not a good place from which to learn zsh for the first time. (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); its compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2. Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. There are also now separate ports for Windows and OS/2, see `Where do I get it' below. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.5 is the latest production version. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.2 has also been released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@cs.elte.hu>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Australia ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ The Windows port mentioned above is maintained separately by Amol Deshpande <amold@microsoft.com>; please mail Amol directly about any Windows-specific problems. This is quite new, so don't expect it to be perfect. You can get it from: ftp://ftp.blarg.net/users/amol/zsh Likewise the OS/2 port is available from TAMURA Kent <kent@tril.ibm.co.jp> at http://cgi.din.or.jp/~tkent/tmp/zsh-3.0.0-os2-a01.zip Starting from mid-October 1997, there is an archive of patches sent to the maintainers' mailing list. Note that these may not all be added to the shell, and some may already have been; you simply have to search for something you might want which is not in the version you have. Also, there may be some prerequisites earlier in the archive. It can be found on the zsh WWW pages (as described in 1.1) at: http://www.peak.org/zsh/Patches/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. o In `cmd1 && cmd2 &', only `cmd2' instead of the whole expression is run in the background in zsh. The manual implies this is a bug. Use `{ cmd1 && cmd2 } &' as a workaround. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o Globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o In `let "i = foo"', foo is evaluated as a number, not an expression (in `let "i = $foo"', however, it is treated as an expression). o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. The introduction of loadable in modules in version 3.1 should help. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: How do I make the completion list use eight bit characters? A traditional UNIX environment (character terminal and ASCII character sets) is not sufficient to be able to handle non-ASCII characters, and there are so many possible enhancements that in general this is hard. However, if you have something like an xterm using a standard character set like ISO-8859-1 (which is often the default for xterm), read on. You should also note question 3.4 on the subject of eight bit characters. You are probably creating files with names including non-ASCII accented characters, and find they show up in the completion list as \M-i or something such. This is because the library routines (not zsh itself) which test whether a character is printable have replied that it is not; zsh has simply found a way to show them anyway. The answer, under a modern POSIXy operating system, is to find a locale where these are treated as printable characters. Zsh has handling for locales built in and will recognise when you set a relevant variable. You need to look in /usr/lib/locale to find one which suits you; the subdirectories correspond to the locale names. The simplest possibility is likely to be en_US, so that the simplest answer to your problem is to set LC_CTYPE=en_US when your terminal is capable of showing eight bit characters. If you only have a default domain (called C), you may need to have some additional files installed on your system. 3.7: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.8: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.9: Why do my autoloaded functions not autoload [the first time]? The problem is that there are two possible ways of autoloading a function (see the AUTOLOADING FUNCTIONS section of the zsh manual page zshmisc for more detailed information): 1) The file contains just the body of the function, i.e. there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. This is the traditional zsh method. The advantage is that the file is called exactly like a script, so can double as both. To define a function `xhead () { print -n "\033]2;$*\a"; }', the file would just contain `print -n "\033]2;$*\a"'. 2) The file contains the entire definition, and maybe even other code: it is run when the function needs to be loaded, then the function itself is called up. This is the method in ksh. To define the same function `xhead', the whole of the usual definition should be in the file. In old versions of zsh, before 3.0, only the first behaviour was allowed, so you had to make sure the file found for autoload just contained the function body. You could still define other functions in the file with the standard form for definitions, though they would be redefined each time you called the main function. In version 3.0.x, the second behaviour is activated if the file defines the autoloaded function. Unfortunately, this is incompatible with the old zsh behaviour which allowed you to redefine the function when you called it. From version 3.1, there is an option KSHAUTOLOAD to allow full ksh compatiblity, i.e. the function _must_ be in the second form above. If that is not set, zsh tries to guess which form you are using: if the file contains only a complete definition of the function in the second form, and nothing else apart from comments and whitespace, it will use the function defined in the file; otherwise, it will assume the old behaviour. The option is set if `emulate ksh' is in effect, of course. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.10: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.11: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.12: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.13: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. 3.14: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.15: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.16: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. 3.17: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.18: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. 3.19: Why is my history not being saved? In zsh, you need to set three variables to make sure your history is written out when the shell exits. For example, HISTSIZE=200 HISTFILE=~/.zsh_history SAVEHIST=200 $HISTSIZE tells the shell how many lines to keep internally, $HISTFILE tells it where to write the history, and $SAVEHIST, the easiest one to forget, tells it how many to write out. The simplest possibility is to set it to the same as $HISTSIZE as above. There are also various options affecting history; see the manual. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.4.) 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. 4.4: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.5: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. (A fix for this will appear shortly.) o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. o Nested closures in extended globbing and pattern matching, such as [[ fofo = (fo#)# ]] are not correctly handled (this will be fixed in version 3.1). Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o history-search-{forward,backward} (bound to \M-n, \M-p) now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For an approximation to the old behaviour, use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, as in ksh, instead of as a new function level. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o Mytt(foo=*) does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so mail on any issues (bug reports, suggestions, complaints...) related to the development of the shell should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (now a traditional item). o Binding of shell functions to key strokes, accessing editing buffer from functions, executing zle functions as a command: now under development for 3.1. o Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.peak.org/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1998/3/24 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.16 1998/03/24 08:53:23 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996, 1997, 1998 (see end of document) Changes since last issue: 1.6 New address for Zoltan This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. How do I make the completion list use eight bit characters? 3.7. Why does my terminal act funny in some way? 3.8. Why does zsh not work in an Emacs shell mode any more? 3.9. Why do my autoloaded functions not autoload [the first time]? 3.10. How does base arithmetic work? 3.11. How do I get a newline in my prompt? 3.12. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.13. Why can't I bind \C-s and \C-q any more? 3.14. How do I execute command `foo' within function `foo'? 3.15. Why do history substitutions with single bangs do something funny? 3.16. Why does zsh kill off all my background jobs when I logout? 3.17. How do I list all my history entries? 3.18. How does the alternative loop syntax, e.g. `while {...} {...}' work? 3.19. Why is my history not being saved? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I get started with programmable completion? 4.5. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://www.peak.org/zsh/ (note the change of address from the end of April 1997). The server provides this FAQ and much else and is now maintained by Timothy Luoma. The FAQ is at http://www.peak.org/zsh/FAQ/ . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. There is now a preliminary version of a reference card for zsh 3.0, which you can find (while it's being developed) at http://www.ifh.de/~pws/computing/refcard.ps This is optimised for A4 paper. The LaTeX source is in the same place with the extension .tex. It is not a good place from which to learn zsh for the first time. (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); its compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2. Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. There are also now separate ports for Windows and OS/2, see `Where do I get it' below. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.5 is the latest production version. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.2 has also been released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Zoltan Hidvegi <hzoli@frontiernet.net>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Australia ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ The Windows port mentioned above is maintained separately by Amol Deshpande <amold@microsoft.com>; please mail Amol directly about any Windows-specific problems. This is quite new, so don't expect it to be perfect. You can get it from: ftp://ftp.blarg.net/users/amol/zsh Likewise the OS/2 port is available from TAMURA Kent <kent@tril.ibm.co.jp> at http://cgi.din.or.jp/~tkent/tmp/zsh-3.0.0-os2-a01.zip Starting from mid-October 1997, there is an archive of patches sent to the maintainers' mailing list. Note that these may not all be added to the shell, and some may already have been; you simply have to search for something you might want which is not in the version you have. Also, there may be some prerequisites earlier in the archive. It can be found on the zsh WWW pages (as described in 1.1) at: http://www.peak.org/zsh/Patches/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. o In `cmd1 && cmd2 &', only `cmd2' instead of the whole expression is run in the background in zsh. The manual implies this is a bug. Use `{ cmd1 && cmd2 } &' as a workaround. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o Globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o In `let "i = foo"', foo is evaluated as a number, not an expression (in `let "i = $foo"', however, it is treated as an expression). o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. The introduction of loadable in modules in version 3.1 should help. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: How do I make the completion list use eight bit characters? A traditional UNIX environment (character terminal and ASCII character sets) is not sufficient to be able to handle non-ASCII characters, and there are so many possible enhancements that in general this is hard. However, if you have something like an xterm using a standard character set like ISO-8859-1 (which is often the default for xterm), read on. You should also note question 3.4 on the subject of eight bit characters. You are probably creating files with names including non-ASCII accented characters, and find they show up in the completion list as \M-i or something such. This is because the library routines (not zsh itself) which test whether a character is printable have replied that it is not; zsh has simply found a way to show them anyway. The answer, under a modern POSIXy operating system, is to find a locale where these are treated as printable characters. Zsh has handling for locales built in and will recognise when you set a relevant variable. You need to look in /usr/lib/locale to find one which suits you; the subdirectories correspond to the locale names. The simplest possibility is likely to be en_US, so that the simplest answer to your problem is to set LC_CTYPE=en_US when your terminal is capable of showing eight bit characters. If you only have a default domain (called C), you may need to have some additional files installed on your system. 3.7: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.8: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.9: Why do my autoloaded functions not autoload [the first time]? The problem is that there are two possible ways of autoloading a function (see the AUTOLOADING FUNCTIONS section of the zsh manual page zshmisc for more detailed information): 1) The file contains just the body of the function, i.e. there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. This is the traditional zsh method. The advantage is that the file is called exactly like a script, so can double as both. To define a function `xhead () { print -n "\033]2;$*\a"; }', the file would just contain `print -n "\033]2;$*\a"'. 2) The file contains the entire definition, and maybe even other code: it is run when the function needs to be loaded, then the function itself is called up. This is the method in ksh. To define the same function `xhead', the whole of the usual definition should be in the file. In old versions of zsh, before 3.0, only the first behaviour was allowed, so you had to make sure the file found for autoload just contained the function body. You could still define other functions in the file with the standard form for definitions, though they would be redefined each time you called the main function. In version 3.0.x, the second behaviour is activated if the file defines the autoloaded function. Unfortunately, this is incompatible with the old zsh behaviour which allowed you to redefine the function when you called it. From version 3.1, there is an option KSHAUTOLOAD to allow full ksh compatiblity, i.e. the function _must_ be in the second form above. If that is not set, zsh tries to guess which form you are using: if the file contains only a complete definition of the function in the second form, and nothing else apart from comments and whitespace, it will use the function defined in the file; otherwise, it will assume the old behaviour. The option is set if `emulate ksh' is in effect, of course. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.10: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.11: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.12: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.13: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. 3.14: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.15: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.16: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. 3.17: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.18: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. 3.19: Why is my history not being saved? In zsh, you need to set three variables to make sure your history is written out when the shell exits. For example, HISTSIZE=200 HISTFILE=~/.zsh_history SAVEHIST=200 $HISTSIZE tells the shell how many lines to keep internally, $HISTFILE tells it where to write the history, and $SAVEHIST, the easiest one to forget, tells it how many to write out. The simplest possibility is to set it to the same as $HISTSIZE as above. There are also various options affecting history; see the manual. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.4.) 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. 4.4: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.5: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. (A fix for this will appear shortly.) o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. o Nested closures in extended globbing and pattern matching, such as [[ fofo = (fo#)# ]] are not correctly handled (this will be fixed in version 3.1). Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o history-search-{forward,backward} (bound to \M-n, \M-p) now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For an approximation to the old behaviour, use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, as in ksh, instead of as a new function level. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o Mytt(foo=*) does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so mail on any issues (bug reports, suggestions, complaints...) related to the development of the shell should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (now a traditional item). o Binding of shell functions to key strokes, accessing editing buffer from functions, executing zle functions as a command: now under development for 3.1. o Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.peak.org/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1998/4/24 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.17 1998/04/24 17:10:21 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996, 1997, 1998 (see end of document) Changes since last issue: 1.6 New archive maintainer 3.7 New item: why do the cursor (arrow) keys not work? This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. How do I make the completion list use eight bit characters? 3.7. Why do the cursor (arrow) keys not work? 3.8. Why does my terminal act funny in some way? 3.9. Why does zsh not work in an Emacs shell mode any more? 3.10. Why do my autoloaded functions not autoload [the first time]? 3.11. How does base arithmetic work? 3.12. How do I get a newline in my prompt? 3.13. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.14. Why can't I bind \C-s and \C-q any more? 3.15. How do I execute command `foo' within function `foo'? 3.16. Why do history substitutions with single bangs do something funny? 3.17. Why does zsh kill off all my background jobs when I logout? 3.18. How do I list all my history entries? 3.19. How does the alternative loop syntax, e.g. `while {...} {...}' work? 3.20. Why is my history not being saved? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I get started with programmable completion? 4.5. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://www.peak.org/zsh/ (note the change of address from the end of April 1997). The server provides this FAQ and much else and is now maintained by Timothy Luoma. The FAQ is at http://www.peak.org/zsh/FAQ/ . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. There is now a preliminary version of a reference card for zsh 3.0, which you can find (while it's being developed) at http://www.ifh.de/~pws/computing/refcard.ps This is optimised for A4 paper. The LaTeX source is in the same place with the extension .tex. It is not a good place from which to learn zsh for the first time. (As a method of reading this in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); its compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2. Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. There are also now separate ports for Windows and OS/2, see `Where do I get it' below. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This make the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.5 is the latest production version. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.2 has also been released; 3.1.3 is expected to appear shortly. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Andrew Main <zefram@tao.co.uk>. The following are known mirrors (kept frequently up to date); the first is the official archive site. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. Australia ftp://mason.primenet.com.au/pub/zsh/ ftp://ftp.ips.gov.au/mirror/zsh/ Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ The Windows port mentioned above is maintained separately by Amol Deshpande <amold@microsoft.com>; please mail Amol directly about any Windows-specific problems. This is quite new, so don't expect it to be perfect. You can get it from: ftp://ftp.blarg.net/users/amol/zsh Likewise the OS/2 port is available from TAMURA Kent <kent@tril.ibm.co.jp> at http://cgi.din.or.jp/~tkent/tmp/zsh-3.0.0-os2-a01.zip Starting from mid-October 1997, there is an archive of patches sent to the maintainers' mailing list. Note that these may not all be added to the shell, and some may already have been; you simply have to search for something you might want which is not in the version you have. Also, there may be some prerequisites earlier in the archive. It can be found on the zsh WWW pages (as described in 1.1) at: http://www.peak.org/zsh/Patches/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. o In `cmd1 && cmd2 &', only `cmd2' instead of the whole expression is run in the background in zsh. The manual implies this is a bug. Use `{ cmd1 && cmd2 } &' as a workaround. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o Globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o In `let "i = foo"', foo is evaluated as a number, not an expression (in `let "i = $foo"', however, it is treated as an expression). o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. The introduction of loadable in modules in version 3.1 should help. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (shwordsplit) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of shwordsplit. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on shwordsplit for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled shwordsplit; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). Shwordsplit is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: How do I make the completion list use eight bit characters? A traditional UNIX environment (character terminal and ASCII character sets) is not sufficient to be able to handle non-ASCII characters, and there are so many possible enhancements that in general this is hard. However, if you have something like an xterm using a standard character set like ISO-8859-1 (which is often the default for xterm), read on. You should also note question 3.4 on the subject of eight bit characters. You are probably creating files with names including non-ASCII accented characters, and find they show up in the completion list as \M-i or something such. This is because the library routines (not zsh itself) which test whether a character is printable have replied that it is not; zsh has simply found a way to show them anyway. The answer, under a modern POSIXy operating system, is to find a locale where these are treated as printable characters. Zsh has handling for locales built in and will recognise when you set a relevant variable. You need to look in /usr/lib/locale to find one which suits you; the subdirectories correspond to the locale names. The simplest possibility is likely to be en_US, so that the simplest answer to your problem is to set LC_CTYPE=en_US when your terminal is capable of showing eight bit characters. If you only have a default domain (called C), you may need to have some additional files installed on your system. 3.7: Why do the cursor (arrow) keys not work? The cursor keys send different codes depending on the terminal; zsh only binds the most well known versions. If you see these problems, try putting the following in your .zshrc: bindkey "$(echotc kl)" backward-char bindkey "$(echotc kr)" forward-char bindkey "$(echotc ku)" up-line-or-history bindkey "$(echotc kd)" down-line-or-history If you use vi mode, use `vi-backward-char' and `vi-forward-char' where appropriate. Note, however, that up to version 3.0 binding arbitrary multiple key sequences can cause problems, so check that this works with your set up first. Also, from version 3.1.3, more sequences are supported by default, namely those in the form `<ESC>O' followed by A, B, C or D, as well as the corresponding set beginning `<ESC>[', so this may be redundant. 3.8: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.9: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.10: Why do my autoloaded functions not autoload [the first time]? The problem is that there are two possible ways of autoloading a function (see the AUTOLOADING FUNCTIONS section of the zsh manual page zshmisc for more detailed information): 1) The file contains just the body of the function, i.e. there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. This is the traditional zsh method. The advantage is that the file is called exactly like a script, so can double as both. To define a function `xhead () { print -n "\033]2;$*\a"; }', the file would just contain `print -n "\033]2;$*\a"'. 2) The file contains the entire definition, and maybe even other code: it is run when the function needs to be loaded, then the function itself is called up. This is the method in ksh. To define the same function `xhead', the whole of the usual definition should be in the file. In old versions of zsh, before 3.0, only the first behaviour was allowed, so you had to make sure the file found for autoload just contained the function body. You could still define other functions in the file with the standard form for definitions, though they would be redefined each time you called the main function. In version 3.0.x, the second behaviour is activated if the file defines the autoloaded function. Unfortunately, this is incompatible with the old zsh behaviour which allowed you to redefine the function when you called it. From version 3.1, there is an option KSHAUTOLOAD to allow full ksh compatiblity, i.e. the function _must_ be in the second form above. If that is not set, zsh tries to guess which form you are using: if the file contains only a complete definition of the function in the second form, and nothing else apart from comments and whitespace, it will use the function defined in the file; otherwise, it will assume the old behaviour. The option is set if `emulate ksh' is in effect, of course. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.11: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.12: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.13: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.14: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in .zshrc. 3.15: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.16: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.17: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. 3.18: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.19: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. 3.20: Why is my history not being saved? In zsh, you need to set three variables to make sure your history is written out when the shell exits. For example, HISTSIZE=200 HISTFILE=~/.zsh_history SAVEHIST=200 $HISTSIZE tells the shell how many lines to keep internally, $HISTFILE tells it where to write the history, and $SAVEHIST, the easiest one to forget, tells it how many to write out. The simplest possibility is to set it to the same as $HISTSIZE as above. There are also various options affecting history; see the manual. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin comman, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.4.) 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. 4.4: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.5: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. (A fix for this will appear shortly.) o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. o Nested closures in extended globbing and pattern matching, such as [[ fofo = (fo#)# ]] are not correctly handled (this will be fixed in version 3.1). Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o history-search-{forward,backward} (bound to \M-n, \M-p) now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For an approximation to the old behaviour, use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, as in ksh, instead of as a new function level. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o Mytt(foo=*) does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so mail on any issues (bug reports, suggestions, complaints...) related to the development of the shell should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (now a traditional item). o Binding of shell functions to key strokes, accessing editing buffer from functions, executing zle functions as a command: now under development for 3.1. o Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman and Zoltan Hidvegi, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://www.peak.org/zsh/".
------- Forwarded Message Date: Thu, 25 Jun 1998 05:14:41 -0400 From: Peter Stephenson <pws@ibmth.df.unipi.it> To: zsh-announce@math.gatech.edu Subject: Z-Shell Frequently Asked Questions (monthly posting) Archive-Name: unix-faq/shell/zsh Last-Modified: 1998/6/1 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.23 1998/06/01 08:55:08 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996, 1997, 1998 (see end of document) Changes since issue posted May 1998: 1.5 New beta version 3.1.4. 1.6 Updated list of sites. 4.3 Note about listambiguous and autolist. 5.2 Finally caught up with mailing list archive. This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. How do I make the completion list use eight bit characters? 3.7. Why do the cursor (arrow) keys not work? 3.8. Why does my terminal act funny in some way? 3.9. Why does zsh not work in an Emacs shell mode any more? 3.10. Why do my autoloaded functions not autoload [the first time]? 3.11. How does base arithmetic work? 3.12. How do I get a newline in my prompt? 3.13. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.14. Why can't I bind \C-s and \C-q any more? 3.15. How do I execute command `foo' within function `foo'? 3.16. Why do history substitutions with single bangs do something funny? 3.17. Why does zsh kill off all my background jobs when I logout? 3.18. How do I list all my history entries? 3.19. How does the alternative loop syntax, e.g. `while {...} {...}' work? 3.20. Why is my history not being saved? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I get started with programmable completion? 4.5. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? Acknowledgments Copyright - --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://sunsite.auc.dk/zsh/ (note the change of address from the end of April 1998). The server provides this FAQ and much else and is now maintained by Karsten Thygesen and others (mail zsh@sunsite.auc.dk with any related messages). The FAQ is at http://sunsite.auc.dk/zsh/FAQ/ . This document was originally written in YODL, allowing it to be converted easily into various other formats. The master source file lives at http://sunsite.auc.dk/zsh/FAQ/zshfaq.yo . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. There is now a preliminary version of a reference card for zsh 3.0, which you can find (while it's being developed) at http://www.ifh.de/~pws/computing/refcard.ps This is optimised for A4 paper. The LaTeX source is in the same place with the extension .tex. It is not a good place from which to learn zsh for the first time. (As a method of reading the following in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); its compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2. Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. There are also now separate ports for Windows and OS/2, see `Where do I get it' below. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This makes the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.5 is the latest production version. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.4 has been released. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Andrew Main <zefram@tao.co.uk>. The following are known mirrors (kept frequently up to date); the first is the official archive site, currently in Australia. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. The following list also appears on the WWW at http://www.zsh.org . Home site ftp://ftp.zsh.org Australia ftp://ftp.ips.gov.au/mirror/zsh/ Denmark ftp://sunsite.auc.dk/pub/unix/shells/zsh Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Israel ftp://ftp.math.technion.ac.il/mirror/ftp.zsh.org/pub/zsh/ http://www.math.technion.ac.il/mirror/ftp.zsh.org/pub/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Romania ftp://ftp.roedu.net/pub/mirrors/ftp.zsh.org/pub/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ The Windows port mentioned above is maintained separately by Amol Deshpande <amold@microsoft.com>; please mail Amol directly about any Windows-specific problems. This is quite new, so don't expect it to be perfect. You can get it from: ftp://ftp.blarg.net/users/amol/zsh Likewise the OS/2 port is available from TAMURA Kent <kent@tril.ibm.co.jp> at http://cgi.din.or.jp/~tkent/tmp/zsh-3.0.0-os2-a01.zip Starting from mid-October 1997, there is an archive of patches sent to the maintainers' mailing list. Note that these may not all be added to the shell, and some may already have been; you simply have to search for something you might want which is not in the version you have. Also, there may be some prerequisites earlier in the archive. It can be found on the zsh WWW pages (as described in 1.1) at: http://sunsite.auc.dk/zsh/Patches/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences with ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_GLOB, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. Handling of coprocess file descriptors is also different. o In `cmd1 && cmd2 &', only `cmd2' instead of the whole expression is run in the background in zsh. The manual implies this is a bug. Use `{ cmd1 && cmd2 } &' as a workaround. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o * Standard globbing does not allow ksh-style `pattern-lists'. Equivalents: - ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. - ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. From version 3.1.3, the ksh forms are fully supported when the option KSH_GLOB is in effect; for previous versions you must use the table above. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o In `let "i = foo"', foo is evaluated as a number, not an expression (in `let "i = $foo"', however, it is treated as an expression). o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. The introduction of loadable in modules in version 3.1 should help. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (SHWORDSPLIT) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of SHWORDSPLIT. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on SHWORDSPLIT for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled SHWORDSPLIT; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). SHWORDSPLIT is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: How do I make the completion list use eight bit characters? A traditional UNIX environment (character terminal and ASCII character sets) is not sufficient to be able to handle non-ASCII characters, and there are so many possible enhancements that in general this is hard. However, if you have something like an xterm using a standard character set like ISO-8859-1 (which is often the default for xterm), read on. You should also note question 3.4 on the subject of eight bit characters. You are probably creating files with names including non-ASCII accented characters, and find they show up in the completion list as \M-i or something such. This is because the library routines (not zsh itself) which test whether a character is printable have replied that it is not; zsh has simply found a way to show them anyway. The answer, under a modern POSIXy operating system, is to find a locale where these are treated as printable characters. Zsh has handling for locales built in and will recognise when you set a relevant variable. You need to look in /usr/lib/locale to find one which suits you; the subdirectories correspond to the locale names. The simplest possibility is likely to be en_US, so that the simplest answer to your problem is to set LC_CTYPE=en_US when your terminal is capable of showing eight bit characters. If you only have a default domain (called C), you may need to have some additional files installed on your system. 3.7: Why do the cursor (arrow) keys not work? The cursor keys send different codes depending on the terminal; zsh only binds the most well known versions. If you see these problems, try putting the following in your .zshrc: bindkey "$(echotc kl)" backward-char bindkey "$(echotc kr)" forward-char bindkey "$(echotc ku)" up-line-or-history bindkey "$(echotc kd)" down-line-or-history If you use vi mode, use `vi-backward-char' and `vi-forward-char' where appropriate. Note, however, that up to version 3.0 binding arbitrary multiple key sequences can cause problems, so check that this works with your set up first. Also, from version 3.1.3, more sequences are supported by default, namely those in the form `<ESC>O' followed by A, B, C or D, as well as the corresponding set beginning `<ESC>[', so this may be redundant. 3.8: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.9: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.10: Why do my autoloaded functions not autoload [the first time]? The problem is that there are two possible ways of autoloading a function (see the AUTOLOADING FUNCTIONS section of the zsh manual page zshmisc for more detailed information): 1) The file contains just the body of the function, i.e. there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. This is the traditional zsh method. The advantage is that the file is called exactly like a script, so can double as both. To define a function `xhead () { print -n "\033]2;$*\a"; }', the file would just contain `print -n "\033]2;$*\a"'. 2) The file contains the entire definition, and maybe even other code: it is run when the function needs to be loaded, then the function itself is called up. This is the method in ksh. To define the same function `xhead', the whole of the usual definition should be in the file. In old versions of zsh, before 3.0, only the first behaviour was allowed, so you had to make sure the file found for autoload just contained the function body. You could still define other functions in the file with the standard form for definitions, though they would be redefined each time you called the main function. In version 3.0.x, the second behaviour is activated if the file defines the autoloaded function. Unfortunately, this is incompatible with the old zsh behaviour which allowed you to redefine the function when you called it. From version 3.1, there is an option KSHAUTOLOAD to allow full ksh compatiblity, i.e. the function _must_ be in the second form above. If that is not set, zsh tries to guess which form you are using: if the file contains only a complete definition of the function in the second form, and nothing else apart from comments and whitespace, it will use the function defined in the file; otherwise, it will assume the old behaviour. The option is set if `emulate ksh' is in effect, of course. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.11: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.12: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.13: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.14: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in your .zshrc file. 3.15: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.16: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.17: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. Likewise, you can start a background job with `&!' instead of just `&' at the end, which will automatically disown the job. 3.18: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.19: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. 3.20: Why is my history not being saved? In zsh, you need to set three variables to make sure your history is written out when the shell exits. For example, HISTSIZE=200 HISTFILE=~/.zsh_history SAVEHIST=200 $HISTSIZE tells the shell how many lines to keep internally, $HISTFILE tells it where to write the history, and $SAVEHIST, the easiest one to forget, tells it how many to write out. The simplest possibility is to set it to the same as $HISTSIZE as above. There are also various options affecting history; see the manual. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin command, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.4.) 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. o Finally, although it affects all completion lists, including those explicitly requested, note also alwayslastprompt, which causes the cursor to return to the line you were editing after printing the list, provided that is short enough. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. Note that from version 3.1 listambiguous is set by default; if you use autolist, you may well want to `unsetopt listambiguous'. 4.4: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. You must be careful to put the whole expression inside quotation marks, so that it appears as a single argument to compctl. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.5: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed what's on the line already, but it can return anything it likes via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. (This is fixed in 3.1.) o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. o Nested closures in extended globbing and pattern matching, such as [[ fofo = (fo#)# ]] are not correctly handled, and there were problems with complicated exclusions using `^' or `~'. (These are fixed in version 3.1.3.) Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o The options ALWAYS_LAST_PROMPT (return to the line you were editing after displaying completion lists) and LIST_AMBIGUOUS (show matching files when there are several) are now set by default. This is in response to complaints that too many zsh features are never noticed by many users. To turn them off, just put `unsetopt alwayslastprompt listambiguous' in your .zshrc file. o history-search-{forward,backward} (bound to \M-n, \M-p) now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For an approximation to the old behaviour, use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, as in ksh, instead of as a new function level. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so mail on any issues (bug reports, suggestions, complaints...) related to the development of the shell should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. More recent mailings up to date are to be found at http://www.zsh.org/mla/ at the main zsh archive in Australia. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (a traditional item). o Binding of shell functions to key strokes, accessing editing buffer from functions, executing zle functions as a command: now under development for 3.1. o Users should be able to create their own foopath/FOOPATH array/path combinations. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman, Zoltan Hidvegi and Andrew Main, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://sunsite.auc.dk/zsh/". ------- End of Forwarded Message
Archive-Name: unix-faq/shell/zsh Last-Modified: 1998/7/27 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.25 1998/07/27 13:59:48 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996, 1997, 1998 (see end of document) Changes since issue posted June 1998: 2.1 `let' behaviour more ksh-like, `$LINENO' not. 4.5 Mention `read -c'. 5.1 Slight update on history-search-backward saga 5.4 Note on year 2000 issues This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. How do I make the completion list use eight bit characters? 3.7. Why do the cursor (arrow) keys not work? 3.8. Why does my terminal act funny in some way? 3.9. Why does zsh not work in an Emacs shell mode any more? 3.10. Why do my autoloaded functions not autoload [the first time]? 3.11. How does base arithmetic work? 3.12. How do I get a newline in my prompt? 3.13. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.14. Why can't I bind \C-s and \C-q any more? 3.15. How do I execute command `foo' within function `foo'? 3.16. Why do history substitutions with single bangs do something funny? 3.17. Why does zsh kill off all my background jobs when I logout? 3.18. How do I list all my history entries? 3.19. How does the alternative loop syntax, e.g. `while {...} {...}' work? 3.20. Why is my history not being saved? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I get started with programmable completion? 4.5. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? 5.4. Will zsh have problems in the year 2000? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://sunsite.auc.dk/zsh/ (note the change of address from the end of April 1998). The server provides this FAQ and much else and is now maintained by Karsten Thygesen and others (mail zsh@sunsite.auc.dk with any related messages). The FAQ is at http://sunsite.auc.dk/zsh/FAQ/ . This document was originally written in YODL, allowing it to be converted easily into various other formats. The master source file lives at http://sunsite.auc.dk/zsh/FAQ/zshfaq.yo . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. There is now a preliminary version of a reference card for zsh 3.0, which you can find (while it's being developed) at http://www.ifh.de/~pws/computing/refcard.ps This is optimised for A4 paper. The LaTeX source is in the same place with the extension .tex. It is not a good place from which to learn zsh for the first time. (As a method of reading the following in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); its compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2). Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. There are also now separate ports for Windows and OS/2, see `Where do I get it' below. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This makes the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.5 is the latest production version. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.4 is also available. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Andrew Main <zefram@tao.co.uk>. The following are known mirrors (kept frequently up to date); the first is the official archive site, currently in Australia. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. The following list also appears on the WWW at http://www.zsh.org . Home site ftp://ftp.zsh.org Australia ftp://ftp.ips.gov.au/mirror/zsh/ Denmark ftp://sunsite.auc.dk/pub/unix/shells/zsh Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Israel ftp://ftp.math.technion.ac.il/mirror/ftp.zsh.org/pub/zsh/ http://www.math.technion.ac.il/mirror/ftp.zsh.org/pub/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Romania ftp://ftp.roedu.net/pub/mirrors/ftp.zsh.org/pub/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) ftp://src.doc.ic.ac.uk/packages/unix/shells/zsh/ USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ The Windows port mentioned above is maintained separately by Amol Deshpande <amold@microsoft.com>; please mail Amol directly about any Windows-specific problems. This is quite new, so don't expect it to be perfect. You can get it from: ftp://ftp.blarg.net/users/amol/zsh Likewise the OS/2 port is available from TAMURA Kent <kent@tril.ibm.co.jp> at http://cgi.din.or.jp/~tkent/tmp/zsh-3.0.0-os2-a01.zip Starting from mid-October 1997, there is an archive of patches sent to the maintainers' mailing list. Note that these may not all be added to the shell, and some may already have been; you simply have to search for something you might want which is not in the version you have. Also, there may be some prerequisites earlier in the archive. It can be found on the zsh WWW pages (as described in 1.1) at: http://sunsite.auc.dk/zsh/Patches/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences from ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different for versions before 3.1.3 --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_GLOB, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. Handling of coprocess file descriptors is also different. o In `cmd1 && cmd2 &', only `cmd2' instead of the whole expression is run in the background in zsh. The manual implies this is a bug. Use `{ cmd1 && cmd2 } &' as a workaround. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o * Standard globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. From version 3.1.3, the ksh forms are fully supported when the option KSH_GLOB is in effect; for previous versions you must use the table above. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o The line number in `$LINENO' can be capricious in zsh scripts. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. The introduction of loadable in modules in version 3.1 should help. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (SHWORDSPLIT) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of SHWORDSPLIT. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on SHWORDSPLIT for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled SHWORDSPLIT; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). SHWORDSPLIT is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: How do I make the completion list use eight bit characters? A traditional UNIX environment (character terminal and ASCII character sets) is not sufficient to be able to handle non-ASCII characters, and there are so many possible enhancements that in general this is hard. However, if you have something like an xterm using a standard character set like ISO-8859-1 (which is often the default for xterm), read on. You should also note question 3.4 on the subject of eight bit characters. You are probably creating files with names including non-ASCII accented characters, and find they show up in the completion list as \M-i or something such. This is because the library routines (not zsh itself) which test whether a character is printable have replied that it is not; zsh has simply found a way to show them anyway. The answer, under a modern POSIXy operating system, is to find a locale where these are treated as printable characters. Zsh has handling for locales built in and will recognise when you set a relevant variable. You need to look in /usr/lib/locale to find one which suits you; the subdirectories correspond to the locale names. The simplest possibility is likely to be en_US, so that the simplest answer to your problem is to set LC_CTYPE=en_US when your terminal is capable of showing eight bit characters. If you only have a default domain (called C), you may need to have some additional files installed on your system. 3.7: Why do the cursor (arrow) keys not work? The cursor keys send different codes depending on the terminal; zsh only binds the most well known versions. If you see these problems, try putting the following in your .zshrc: bindkey "$(echotc kl)" backward-char bindkey "$(echotc kr)" forward-char bindkey "$(echotc ku)" up-line-or-history bindkey "$(echotc kd)" down-line-or-history If you use vi mode, use `vi-backward-char' and `vi-forward-char' where appropriate. Note, however, that up to version 3.0 binding arbitrary multiple key sequences can cause problems, so check that this works with your set up first. Also, from version 3.1.3, more sequences are supported by default, namely those in the form `<ESC>O' followed by A, B, C or D, as well as the corresponding set beginning `<ESC>[', so this may be redundant. 3.8: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.9: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.10: Why do my autoloaded functions not autoload [the first time]? The problem is that there are two possible ways of autoloading a function (see the AUTOLOADING FUNCTIONS section of the zsh manual page zshmisc for more detailed information): 1) The file contains just the body of the function, i.e. there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. This is the traditional zsh method. The advantage is that the file is called exactly like a script, so can double as both. To define a function `xhead () { print -n "\033]2;$*\a"; }', the file would just contain `print -n "\033]2;$*\a"'. 2) The file contains the entire definition, and maybe even other code: it is run when the function needs to be loaded, then the function itself is called up. This is the method in ksh. To define the same function `xhead', the whole of the usual definition should be in the file. In old versions of zsh, before 3.0, only the first behaviour was allowed, so you had to make sure the file found for autoload just contained the function body. You could still define other functions in the file with the standard form for definitions, though they would be redefined each time you called the main function. In version 3.0.x, the second behaviour is activated if the file defines the autoloaded function. Unfortunately, this is incompatible with the old zsh behaviour which allowed you to redefine the function when you called it. From version 3.1, there is an option KSHAUTOLOAD to allow full ksh compatiblity, i.e. the function _must_ be in the second form above. If that is not set, zsh tries to guess which form you are using: if the file contains only a complete definition of the function in the second form, and nothing else apart from comments and whitespace, it will use the function defined in the file; otherwise, it will assume the old behaviour. The option is set if `emulate ksh' is in effect, of course. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.11: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.12: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.13: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.14: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in your .zshrc file. 3.15: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.16: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.17: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. Likewise, you can start a background job with `&!' instead of just `&' at the end, which will automatically disown the job. 3.18: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.19: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. 3.20: Why is my history not being saved? In zsh, you need to set three variables to make sure your history is written out when the shell exits. For example, HISTSIZE=200 HISTFILE=~/.zsh_history SAVEHIST=200 $HISTSIZE tells the shell how many lines to keep internally, $HISTFILE tells it where to write the history, and $SAVEHIST, the easiest one to forget, tells it how many to write out. The simplest possibility is to set it to the same as $HISTSIZE as above. There are also various options affecting history; see the manual. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin command, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.4.) 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. o Finally, although it affects all completion lists, including those explicitly requested, note also alwayslastprompt, which causes the cursor to return to the line you were editing after printing the list, provided that is short enough. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. Note that from version 3.1 listambiguous is set by default; if you use autolist, you may well want to `unsetopt listambiguous'. 4.4: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. You must be careful to put the whole expression inside quotation marks, so that it appears as a single argument to compctl. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.5: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed the part of the word already typed, and can read the rest of the line with `read -c'. It can return a set of completions via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. (This is fixed in 3.1.) o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. o Nested closures in extended globbing and pattern matching, such as [[ fofo = (fo#)# ]] are not correctly handled, and there were problems with complicated exclusions using `^' or `~'. (These are fixed in version 3.1.3.) Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o The options ALWAYS_LAST_PROMPT (return to the line you were editing after displaying completion lists) and LIST_AMBIGUOUS (show matching files when there are several) are now set by default. This is in response to complaints that too many zsh features are never noticed by many users. To turn them off, just put `unsetopt alwayslastprompt listambiguous' in your .zshrc file. o history-search-{forward,backward} now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For this reason, `\M-n' and `\M-p' use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. It is possible to write functions which go a little closer to the original behaviour; further changes are still possible. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, as in ksh, instead of as a new function level. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so mail on any issues (bug reports, suggestions, complaints...) related to the development of the shell should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. More recent mailings up to date are to be found at http://www.zsh.org/mla/ at the main zsh archive in Australia. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (a traditional item). o Binding of shell functions to key strokes, accessing editing buffer from functions, executing zle functions as a command: now under development for 3.1. o Users should be able to create their own foopath/FOOPATH array/path combinations. 5.4: Will zsh have problems in the year 2000? (This information was written by Bart Schaefer. Note it is a description of the state of affairs as seen by the developers, it is not a guarantee!) You can confirm the following by looking at the source code yourself if necessary; there's no other definitive reference: Zsh uses UNIX/POSIX time_t, timeval, and tm data types for internal date manipulations. These types either do not store year values at all (for example, time_t is measured in seconds since midnight, Jan 1, 1970) or store them as integer types and NOT as pairs of digits. Thus there can be no overflows at year 2000. On some unix systems, time_t is a 32-bit value and will overflow during the year 2038, but more modern systems use a 64-bit time_t. The only input and output of dates that zsh performs is optional history time-stamping. This is performed using time_t values converted to long integers, which are either 32 or 64 bits, see above. Note, however, that zsh does provide facilities for formatted date output, so it's possible that scripts written for zsh might employ 2-digit years. Shell scripts should always be considered separate programs and therefore evaluated individually. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman, Zoltan Hidvegi and Andrew Main, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997, 1998. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://sunsite.auc.dk/zsh/".
[ After today I shall be away for three weeks, 2 2/7 without email. Please try not to introduce any major incompatibilities into the shell while I'm gone :-) --- pws ] Archive-Name: unix-faq/shell/zsh Last-Modified: 1998/8/21 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.27 1998/08/21 08:39:10 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996, 1997, 1998 (see end of document) Changes since issue posted July 1998: 4.2 Mention directory completion. 4.4 New item `how do I complete in the middle of words / just what's before the cursor?'. This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. How do I make the completion list use eight bit characters? 3.7. Why do the cursor (arrow) keys not work? 3.8. Why does my terminal act funny in some way? 3.9. Why does zsh not work in an Emacs shell mode any more? 3.10. Why do my autoloaded functions not autoload [the first time]? 3.11. How does base arithmetic work? 3.12. How do I get a newline in my prompt? 3.13. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.14. Why can't I bind \C-s and \C-q any more? 3.15. How do I execute command `foo' within function `foo'? 3.16. Why do history substitutions with single bangs do something funny? 3.17. Why does zsh kill off all my background jobs when I logout? 3.18. How do I list all my history entries? 3.19. How does the alternative loop syntax, e.g. `while {...} {...}' work? 3.20. Why is my history not being saved? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I complete in the middle of words / just what's before the cursor? 4.5. How do I get started with programmable completion? 4.6. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? 5.4. Will zsh have problems in the year 2000? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://sunsite.auc.dk/zsh/ (note the change of address from the end of April 1998). The server provides this FAQ and much else and is now maintained by Karsten Thygesen and others (mail zsh@sunsite.auc.dk with any related messages). The FAQ is at http://sunsite.auc.dk/zsh/FAQ/ . This document was originally written in YODL, allowing it to be converted easily into various other formats. The master source file lives at http://sunsite.auc.dk/zsh/FAQ/zshfaq.yo . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. There is now a preliminary version of a reference card for zsh 3.0, which you can find (while it's being developed) at http://www.ifh.de/~pws/computing/refcard.ps This is optimised for A4 paper. The LaTeX source is in the same place with the extension .tex. It is not a good place from which to learn zsh for the first time. (As a method of reading the following in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); its compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2). Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. There are also now separate ports for Windows and OS/2, see `Where do I get it' below. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This makes the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.5 is the latest production version. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.4 is also available. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Andrew Main <zefram@tao.co.uk>. The following are known mirrors (kept frequently up to date); the first is the official archive site, currently in Australia. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. The following list also appears on the WWW at http://www.zsh.org . Home site ftp://ftp.zsh.org Australia ftp://ftp.ips.gov.au/mirror/zsh/ Denmark ftp://sunsite.auc.dk/pub/unix/shells/zsh Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Israel ftp://ftp.math.technion.ac.il/mirror/ftp.zsh.org/pub/zsh/ http://www.math.technion.ac.il/mirror/ftp.zsh.org/pub/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Romania ftp://ftp.roedu.net/pub/mirrors/ftp.zsh.org/pub/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) ftp://src.doc.ic.ac.uk/packages/unix/shells/zsh/ USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ The Windows port mentioned above is maintained separately by Amol Deshpande <amold@microsoft.com>; please mail Amol directly about any Windows-specific problems. This is quite new, so don't expect it to be perfect. You can get it from: ftp://ftp.blarg.net/users/amol/zsh Likewise the OS/2 port is available from TAMURA Kent <kent@tril.ibm.co.jp> at http://cgi.din.or.jp/~tkent/tmp/zsh-3.0.0-os2-a01.zip Starting from mid-October 1997, there is an archive of patches sent to the maintainers' mailing list. Note that these may not all be added to the shell, and some may already have been; you simply have to search for something you might want which is not in the version you have. Also, there may be some prerequisites earlier in the archive. It can be found on the zsh WWW pages (as described in 1.1) at: http://sunsite.auc.dk/zsh/Patches/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences from ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different for versions before 3.1.3 --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_GLOB, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. Handling of coprocess file descriptors is also different. o In `cmd1 && cmd2 &', only `cmd2' instead of the whole expression is run in the background in zsh. The manual implies this is a bug. Use `{ cmd1 && cmd2 } &' as a workaround. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o * Standard globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. From version 3.1.3, the ksh forms are fully supported when the option KSH_GLOB is in effect; for previous versions you must use the table above. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o The line number in `$LINENO' can be capricious in zsh scripts. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. The introduction of loadable in modules in version 3.1 should help. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (SHWORDSPLIT) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of SHWORDSPLIT. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on SHWORDSPLIT for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled SHWORDSPLIT; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). SHWORDSPLIT is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: How do I make the completion list use eight bit characters? A traditional UNIX environment (character terminal and ASCII character sets) is not sufficient to be able to handle non-ASCII characters, and there are so many possible enhancements that in general this is hard. However, if you have something like an xterm using a standard character set like ISO-8859-1 (which is often the default for xterm), read on. You should also note question 3.4 on the subject of eight bit characters. You are probably creating files with names including non-ASCII accented characters, and find they show up in the completion list as \M-i or something such. This is because the library routines (not zsh itself) which test whether a character is printable have replied that it is not; zsh has simply found a way to show them anyway. The answer, under a modern POSIXy operating system, is to find a locale where these are treated as printable characters. Zsh has handling for locales built in and will recognise when you set a relevant variable. You need to look in /usr/lib/locale to find one which suits you; the subdirectories correspond to the locale names. The simplest possibility is likely to be en_US, so that the simplest answer to your problem is to set LC_CTYPE=en_US when your terminal is capable of showing eight bit characters. If you only have a default domain (called C), you may need to have some additional files installed on your system. 3.7: Why do the cursor (arrow) keys not work? The cursor keys send different codes depending on the terminal; zsh only binds the most well known versions. If you see these problems, try putting the following in your .zshrc: bindkey "$(echotc kl)" backward-char bindkey "$(echotc kr)" forward-char bindkey "$(echotc ku)" up-line-or-history bindkey "$(echotc kd)" down-line-or-history If you use vi mode, use `vi-backward-char' and `vi-forward-char' where appropriate. Note, however, that up to version 3.0 binding arbitrary multiple key sequences can cause problems, so check that this works with your set up first. Also, from version 3.1.3, more sequences are supported by default, namely those in the form `<ESC>O' followed by A, B, C or D, as well as the corresponding set beginning `<ESC>[', so this may be redundant. 3.8: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.9: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.10: Why do my autoloaded functions not autoload [the first time]? The problem is that there are two possible ways of autoloading a function (see the AUTOLOADING FUNCTIONS section of the zsh manual page zshmisc for more detailed information): 1) The file contains just the body of the function, i.e. there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. This is the traditional zsh method. The advantage is that the file is called exactly like a script, so can double as both. To define a function `xhead () { print -n "\033]2;$*\a"; }', the file would just contain `print -n "\033]2;$*\a"'. 2) The file contains the entire definition, and maybe even other code: it is run when the function needs to be loaded, then the function itself is called up. This is the method in ksh. To define the same function `xhead', the whole of the usual definition should be in the file. In old versions of zsh, before 3.0, only the first behaviour was allowed, so you had to make sure the file found for autoload just contained the function body. You could still define other functions in the file with the standard form for definitions, though they would be redefined each time you called the main function. In version 3.0.x, the second behaviour is activated if the file defines the autoloaded function. Unfortunately, this is incompatible with the old zsh behaviour which allowed you to redefine the function when you called it. From version 3.1, there is an option KSHAUTOLOAD to allow full ksh compatiblity, i.e. the function _must_ be in the second form above. If that is not set, zsh tries to guess which form you are using: if the file contains only a complete definition of the function in the second form, and nothing else apart from comments and whitespace, it will use the function defined in the file; otherwise, it will assume the old behaviour. The option is set if `emulate ksh' is in effect, of course. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.11: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.12: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.13: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.14: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in your .zshrc file. 3.15: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.16: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.17: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. Likewise, you can start a background job with `&!' instead of just `&' at the end, which will automatically disown the job. 3.18: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.19: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. 3.20: Why is my history not being saved? In zsh, you need to set three variables to make sure your history is written out when the shell exits. For example, HISTSIZE=200 HISTFILE=~/.zsh_history SAVEHIST=200 $HISTSIZE tells the shell how many lines to keep internally, $HISTFILE tells it where to write the history, and $SAVEHIST, the easiest one to forget, tells it how many to write out. The simplest possibility is to set it to the same as $HISTSIZE as above. There are also various options affecting history; see the manual. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin command, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. A useful addition for zsh from version 3.1 is directory completion: compctl -/ cd Before, you had to use -g, but this is neater: it takes care of things like ignoring directories beginning with a dot unless you've typed the dot yourself, and whole directory paths are understood. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.5.) Also, from version 3.1 you can always handle directories at the same time as other files just by adding -/ to the list. 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. o Finally, although it affects all completion lists, including those explicitly requested, note also alwayslastprompt, which causes the cursor to return to the line you were editing after printing the list, provided that is short enough. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. Note that from version 3.1 listambiguous is set by default; if you use autolist, you may well want to `unsetopt listambiguous'. 4.4: How do I complete in the middle of words / just what's before the cursor? Sometimes you have a word on the command-line (let's stick to file names) which is incomplete in the middle. Normally if you hit tab in zsh, it will simply go to the end of the word and try to complete there. However, there are two ways of changing this. First, there is the option COMPLETE_IN_WORD. This tries to fill in the word at the point of the cursor. For example, if the current directory contains `foobar', then with the option set, you can complete `fbar' to `foobar' by moving the cursor to the `b' and hitting tab. That's not the full story, however. Sometimes you just want the part of the word before the cursor completed. For example, the word is `/usr/loc/b', which you want to complete to `/usr/local/bin'. Normally, zsh won't do this in one go because there are two bits missing (but see below!), so you need to complete the `/usr/loc' on its own first. For this you need the function expand-or-complete-prefix: it works mostly like the usual function bound to tab, but it ignores anything on the right of the cursor. If you always want this behaviour (some other shells do this), bind it to tab; otherwise put another binding, e.g. `^X TAB' in ~/.zshrc: bindkey "^X^I" expand-or-complete-prefix then in the example you can move to just after `/usr/loc', hit whatever key you've just bound, move to the end, and hit tab. (Note that AUTO_REMOVE_SLASH behaviour applies here, see the manual.) Even that doesn't exhaust the possibilities. Included with the source distribution is the file Functions/multicomp, a function which you can bind as an alternative form of default completion (see below for a description of alternative completion), e.g. compctl -D -f + -U -Q -K multicomp and whole sequences of directories, like `/usr/loc/b' or even `/u/l/b' can be completed in one go. It works best with menucompletion if the result is ambiguous. 4.5: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. You must be careful to put the whole expression inside quotation marks, so that it appears as a single argument to compctl. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.6: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed the part of the word already typed, and can read the rest of the line with `read -c'. It can return a set of completions via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. (This is fixed in 3.1.) o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. o Nested closures in extended globbing and pattern matching, such as [[ fofo = (fo#)# ]] are not correctly handled, and there were problems with complicated exclusions using `^' or `~'. (These are fixed in version 3.1.3.) Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o The options ALWAYS_LAST_PROMPT (return to the line you were editing after displaying completion lists) and LIST_AMBIGUOUS (show matching files when there are several) are now set by default. This is in response to complaints that too many zsh features are never noticed by many users. To turn them off, just put `unsetopt alwayslastprompt listambiguous' in your .zshrc file. o history-search-{forward,backward} now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For this reason, `\M-n' and `\M-p' use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. It is possible to write functions which go a little closer to the original behaviour; further changes are still possible. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, as in ksh, instead of as a new function level. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so mail on any issues (bug reports, suggestions, complaints...) related to the development of the shell should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. More recent mailings up to date are to be found at http://www.zsh.org/mla/ at the main zsh archive in Australia. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (a traditional item). o Binding of shell functions to key strokes, accessing editing buffer from functions, executing zle functions as a command: now under development for 3.1. o Users should be able to create their own foopath/FOOPATH array/path combinations. 5.4: Will zsh have problems in the year 2000? (This information was written by Bart Schaefer. Note it is a description of the state of affairs as seen by the developers, it is not a guarantee!) You can confirm the following by looking at the source code yourself if necessary; there's no other definitive reference: Zsh uses UNIX/POSIX time_t, timeval, and tm data types for internal date manipulations. These types either do not store year values at all (for example, time_t is measured in seconds since midnight, Jan 1, 1970) or store them as integer types and NOT as pairs of digits. Thus there can be no overflows at year 2000. On some unix systems, time_t is a 32-bit value and will overflow during the year 2038, but more modern systems use a 64-bit time_t. The only input and output of dates that zsh performs is optional history time-stamping. This is performed using time_t values converted to long integers, which are either 32 or 64 bits, see above. Note, however, that zsh does provide facilities for formatted date output, so it's possible that scripts written for zsh might employ 2-digit years. Shell scripts should always be considered separate programs and therefore evaluated individually. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman, Zoltan Hidvegi and Andrew Main, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997, 1998. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://sunsite.auc.dk/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1998/9/24 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.29 1998/09/24 09:56:03 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996, 1997, 1998 (see end of document) Changes since issue posted August 1998: 1.1 Add note on contributed scripts and functions at web site. 4.5 Extra note on differences between `+' and `-x' in compctl 5.1 Moved item on quirks of $LINENO here, as it's really a bug This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. How do I make the completion list use eight bit characters? 3.7. Why do the cursor (arrow) keys not work? 3.8. Why does my terminal act funny in some way? 3.9. Why does zsh not work in an Emacs shell mode any more? 3.10. Why do my autoloaded functions not autoload [the first time]? 3.11. How does base arithmetic work? 3.12. How do I get a newline in my prompt? 3.13. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.14. Why can't I bind \C-s and \C-q any more? 3.15. How do I execute command `foo' within function `foo'? 3.16. Why do history substitutions with single bangs do something funny? 3.17. Why does zsh kill off all my background jobs when I logout? 3.18. How do I list all my history entries? 3.19. How does the alternative loop syntax, e.g. `while {...} {...}' work? 3.20. Why is my history not being saved? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I complete in the middle of words / just what's before the cursor? 4.5. How do I get started with programmable completion? 4.6. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? 5.4. Will zsh have problems in the year 2000? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://sunsite.auc.dk/zsh/ (note the change of address from the end of April 1998). The server provides this FAQ and much else and is now maintained by Karsten Thygesen and others (mail zsh@sunsite.auc.dk with any related messages). The FAQ is at http://sunsite.auc.dk/zsh/FAQ/ . The site also contains some contributed zsh scripts and functions; we are delighted to add more, or simply links to your own collection. This document was originally written in YODL, allowing it to be converted easily into various other formats. The master source file lives at http://sunsite.auc.dk/zsh/FAQ/zshfaq.yo . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. There is now a preliminary version of a reference card for zsh 3.0, which you can find (while it's being developed) at http://www.ifh.de/~pws/computing/refcard.ps This is optimised for A4 paper. The LaTeX source is in the same place with the extension .tex. It is not a good place from which to learn zsh for the first time. (As a method of reading the following in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); its compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2). Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. There are also now separate ports for Windows and OS/2, see `Where do I get it' below. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This makes the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.5 is the latest production version. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.4 is also available. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Andrew Main <zefram@tao.co.uk>. The following are known mirrors (kept frequently up to date); the first is the official archive site, currently in Australia. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. The following list also appears on the WWW at http://www.zsh.org . Home site ftp://ftp.zsh.org Australia ftp://ftp.ips.gov.au/mirror/zsh/ Denmark ftp://sunsite.auc.dk/pub/unix/shells/zsh Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Israel ftp://ftp.math.technion.ac.il/mirror/ftp.zsh.org/pub/zsh/ http://www.math.technion.ac.il/mirror/ftp.zsh.org/pub/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Romania ftp://ftp.roedu.net/pub/mirrors/ftp.zsh.org/pub/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) ftp://src.doc.ic.ac.uk/packages/unix/shells/zsh/ USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ The Windows port mentioned above is maintained separately by Amol Deshpande <amold@microsoft.com>; please mail Amol directly about any Windows-specific problems. This is quite new, so don't expect it to be perfect. You can get it from: ftp://ftp.blarg.net/users/amol/zsh Likewise the OS/2 port is available from TAMURA Kent <kent@tril.ibm.co.jp> at http://cgi.din.or.jp/~tkent/tmp/zsh-3.0.0-os2-a01.zip Starting from mid-October 1997, there is an archive of patches sent to the maintainers' mailing list. Note that these may not all be added to the shell, and some may already have been; you simply have to search for something you might want which is not in the version you have. Also, there may be some prerequisites earlier in the archive. It can be found on the zsh WWW pages (as described in 1.1) at: http://sunsite.auc.dk/zsh/Patches/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences from ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different for versions before 3.1.3 --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_GLOB, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. Handling of coprocess file descriptors is also different. o In `cmd1 && cmd2 &', only `cmd2' instead of the whole expression is run in the background in zsh. The manual implies this is a bug. Use `{ cmd1 && cmd2 } &' as a workaround. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o * Standard globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. From version 3.1.3, the ksh forms are fully supported when the option KSH_GLOB is in effect; for previous versions you must use the table above. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. The introduction of loadable in modules in version 3.1 should help. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (SHWORDSPLIT) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of SHWORDSPLIT. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on SHWORDSPLIT for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled SHWORDSPLIT; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). SHWORDSPLIT is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: How do I make the completion list use eight bit characters? A traditional UNIX environment (character terminal and ASCII character sets) is not sufficient to be able to handle non-ASCII characters, and there are so many possible enhancements that in general this is hard. However, if you have something like an xterm using a standard character set like ISO-8859-1 (which is often the default for xterm), read on. You should also note question 3.4 on the subject of eight bit characters. You are probably creating files with names including non-ASCII accented characters, and find they show up in the completion list as \M-i or something such. This is because the library routines (not zsh itself) which test whether a character is printable have replied that it is not; zsh has simply found a way to show them anyway. The answer, under a modern POSIXy operating system, is to find a locale where these are treated as printable characters. Zsh has handling for locales built in and will recognise when you set a relevant variable. You need to look in /usr/lib/locale to find one which suits you; the subdirectories correspond to the locale names. The simplest possibility is likely to be en_US, so that the simplest answer to your problem is to set LC_CTYPE=en_US when your terminal is capable of showing eight bit characters. If you only have a default domain (called C), you may need to have some additional files installed on your system. 3.7: Why do the cursor (arrow) keys not work? The cursor keys send different codes depending on the terminal; zsh only binds the most well known versions. If you see these problems, try putting the following in your .zshrc: bindkey "$(echotc kl)" backward-char bindkey "$(echotc kr)" forward-char bindkey "$(echotc ku)" up-line-or-history bindkey "$(echotc kd)" down-line-or-history If you use vi mode, use `vi-backward-char' and `vi-forward-char' where appropriate. Note, however, that up to version 3.0 binding arbitrary multiple key sequences can cause problems, so check that this works with your set up first. Also, from version 3.1.3, more sequences are supported by default, namely those in the form `<ESC>O' followed by A, B, C or D, as well as the corresponding set beginning `<ESC>[', so this may be redundant. 3.8: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.9: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.10: Why do my autoloaded functions not autoload [the first time]? The problem is that there are two possible ways of autoloading a function (see the AUTOLOADING FUNCTIONS section of the zsh manual page zshmisc for more detailed information): 1) The file contains just the body of the function, i.e. there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. This is the traditional zsh method. The advantage is that the file is called exactly like a script, so can double as both. To define a function `xhead () { print -n "\033]2;$*\a"; }', the file would just contain `print -n "\033]2;$*\a"'. 2) The file contains the entire definition, and maybe even other code: it is run when the function needs to be loaded, then the function itself is called up. This is the method in ksh. To define the same function `xhead', the whole of the usual definition should be in the file. In old versions of zsh, before 3.0, only the first behaviour was allowed, so you had to make sure the file found for autoload just contained the function body. You could still define other functions in the file with the standard form for definitions, though they would be redefined each time you called the main function. In version 3.0.x, the second behaviour is activated if the file defines the autoloaded function. Unfortunately, this is incompatible with the old zsh behaviour which allowed you to redefine the function when you called it. From version 3.1, there is an option KSHAUTOLOAD to allow full ksh compatiblity, i.e. the function _must_ be in the second form above. If that is not set, zsh tries to guess which form you are using: if the file contains only a complete definition of the function in the second form, and nothing else apart from comments and whitespace, it will use the function defined in the file; otherwise, it will assume the old behaviour. The option is set if `emulate ksh' is in effect, of course. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.11: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.12: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.13: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.14: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in your .zshrc file. 3.15: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.16: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.17: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. Likewise, you can start a background job with `&!' instead of just `&' at the end, which will automatically disown the job. 3.18: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.19: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. 3.20: Why is my history not being saved? In zsh, you need to set three variables to make sure your history is written out when the shell exits. For example, HISTSIZE=200 HISTFILE=~/.zsh_history SAVEHIST=200 $HISTSIZE tells the shell how many lines to keep internally, $HISTFILE tells it where to write the history, and $SAVEHIST, the easiest one to forget, tells it how many to write out. The simplest possibility is to set it to the same as $HISTSIZE as above. There are also various options affecting history; see the manual. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin command, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. A useful addition for zsh from version 3.1 is directory completion: compctl -/ cd Before, you had to use -g, but this is neater: it takes care of things like ignoring directories beginning with a dot unless you've typed the dot yourself, and whole directory paths are understood. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.5.) Also, from version 3.1 you can always handle directories at the same time as other files just by adding -/ to the list. 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. o Finally, although it affects all completion lists, including those explicitly requested, note also alwayslastprompt, which causes the cursor to return to the line you were editing after printing the list, provided that is short enough. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. Note that from version 3.1 listambiguous is set by default; if you use autolist, you may well want to `unsetopt listambiguous'. 4.4: How do I complete in the middle of words / just what's before the cursor? Sometimes you have a word on the command-line (let's stick to file names) which is incomplete in the middle. Normally if you hit tab in zsh, it will simply go to the end of the word and try to complete there. However, there are two ways of changing this. First, there is the option COMPLETE_IN_WORD. This tries to fill in the word at the point of the cursor. For example, if the current directory contains `foobar', then with the option set, you can complete `fbar' to `foobar' by moving the cursor to the `b' and hitting tab. That's not the full story, however. Sometimes you just want the part of the word before the cursor completed. For example, the word is `/usr/loc/b', which you want to complete to `/usr/local/bin'. Normally, zsh won't do this in one go because there are two bits missing (but see below!), so you need to complete the `/usr/loc' on its own first. For this you need the function expand-or-complete-prefix: it works mostly like the usual function bound to tab, but it ignores anything on the right of the cursor. If you always want this behaviour (some other shells do this), bind it to tab; otherwise put another binding, e.g. `^X TAB' in ~/.zshrc: bindkey "^X^I" expand-or-complete-prefix then in the example you can move to just after `/usr/loc', hit whatever key you've just bound, move to the end, and hit tab. (Note that AUTO_REMOVE_SLASH behaviour applies here, see the manual.) Even that doesn't exhaust the possibilities. Included with the source distribution is the file Functions/multicomp, a function which you can bind as an alternative form of default completion (see below for a description of alternative completion), e.g. compctl -D -f + -U -Q -K multicomp and whole sequences of directories, like `/usr/loc/b' or even `/u/l/b' can be completed in one go. It works best with menucompletion if the result is ambiguous. 4.5: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). (Note the difference in the ways `+' and `-x' work. A `+' completion will always try and find completions for what's before the `+' first; it will only produce a list for what's after if the first list was empty. On the other hand, if a condition for a `-x' matches, the appropriate set of completions is always used, even if the list of completions produced is empty.) The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. You must be careful to put the whole expression inside quotation marks, so that it appears as a single argument to compctl. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.6: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed the part of the word already typed, and can read the rest of the line with `read -c'. It can return a set of completions via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o Zsh's notion of the current line number (via $LINENO) is sometimes not well handled, particularly when using functions and traps. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. (This is fixed in 3.1.) o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. o Nested closures in extended globbing and pattern matching, such as [[ fofo = (fo#)# ]] are not correctly handled, and there were problems with complicated exclusions using `^' or `~'. (These are fixed in version 3.1.3.) Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o The options ALWAYS_LAST_PROMPT (return to the line you were editing after displaying completion lists) and LIST_AMBIGUOUS (show matching files when there are several) are now set by default. This is in response to complaints that too many zsh features are never noticed by many users. To turn them off, just put `unsetopt alwayslastprompt listambiguous' in your .zshrc file. o history-search-{forward,backward} now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For this reason, `\M-n' and `\M-p' use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. It is possible to write functions which go a little closer to the original behaviour; further changes are still possible. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, as in ksh, instead of as a new function level. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so mail on any issues (bug reports, suggestions, complaints...) related to the development of the shell should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. More recent mailings up to date are to be found at http://www.zsh.org/mla/ at the main zsh archive in Australia. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (a traditional item). o Binding of shell functions to key strokes, accessing editing buffer from functions, executing zle functions as a command: now under development for 3.1. o Users should be able to create their own foopath/FOOPATH array/path combinations. 5.4: Will zsh have problems in the year 2000? (This information was written by Bart Schaefer. Note it is a description of the state of affairs as seen by the developers, it is not a guarantee!) You can confirm the following by looking at the source code yourself if necessary; there's no other definitive reference: Zsh uses UNIX/POSIX time_t, timeval, and tm data types for internal date manipulations. These types either do not store year values at all (for example, time_t is measured in seconds since midnight, Jan 1, 1970) or store them as integer types and NOT as pairs of digits. Thus there can be no overflows at year 2000. On some unix systems, time_t is a 32-bit value and will overflow during the year 2038, but more modern systems use a 64-bit time_t. The only input and output of dates that zsh performs is optional history time-stamping. This is performed using time_t values converted to long integers, which are either 32 or 64 bits, see above. Note, however, that zsh does provide facilities for formatted date output, so it's possible that scripts written for zsh might employ 2-digit years. Shell scripts should always be considered separate programs and therefore evaluated individually. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman, Zoltan Hidvegi and Andrew Main, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997, 1998. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://sunsite.auc.dk/zsh/".
Archive-Name: unix-faq/shell/zsh Last-Modified: 1998/10/26 Submitted-By: pws@amtp.liv.ac.uk (Peter Stephenson) Version: $Id: zshfaq.yo,v 1.31 1998/10/26 09:43:13 pws Exp $ Frequency: Monthly Copyright: (C) P.W. Stephenson, 1995, 1996, 1997, 1998 (see end of document) Changes since issue posted September 1998: 2.1 Another `typeset' difference turned up. 5.4 Slight addition to Y2K item (prompt formatting) This document contains a list of frequently-asked (or otherwise significant) questions concerning the Z-shell, a command interpreter for many UNIX systems which is freely available to anyone with FTP access. Zsh is among the most powerful freely available Bourne-like shell for interactive use. If you have never heard of `sh', `csh' or `ksh', then you are probably better off to start by reading a general introduction to UNIX rather than this document. If you just want to know how to get your hands on the latest version, skip to question 1.6; if you want to know what to do with insoluble problems, go to 5.2. Notation: Quotes `like this' are ordinary textual quotation marks. Other uses of quotation marks are input to the shell. Contents: Chapter 1: Introducing zsh and how to install it 1.1. Sources of information 1.2. What is it? 1.3. What is it good at? 1.4. On what machines will it run? (Plus important compilation notes) 1.5. What's the latest version? 1.6. Where do I get it? 1.7. I don't have root access: how do I make zsh my login shell? Chapter 2: How does zsh differ from...? 2.1. sh and ksh? 2.2. csh? 2.3. Why do my csh aliases not work? (Plus other alias pitfalls.) 2.4. tcsh? 2.5. bash? 2.6. Shouldn't zsh be more/less like ksh/(t)csh? Chapter 3: How to get various things to work 3.1. Why does `$var' where `var="foo bar"' not do what I expect? 3.2. What is the difference between `export' and the ALL_EXPORT option? 3.3. How do I turn off spelling correction/globbing for a single command? 3.4. How do I get the meta key to work on my xterm? 3.5. How do I automatically display the directory in my xterm title bar? 3.6. How do I make the completion list use eight bit characters? 3.7. Why do the cursor (arrow) keys not work? 3.8. Why does my terminal act funny in some way? 3.9. Why does zsh not work in an Emacs shell mode any more? 3.10. Why do my autoloaded functions not autoload [the first time]? 3.11. How does base arithmetic work? 3.12. How do I get a newline in my prompt? 3.13. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny? 3.14. Why can't I bind \C-s and \C-q any more? 3.15. How do I execute command `foo' within function `foo'? 3.16. Why do history substitutions with single bangs do something funny? 3.17. Why does zsh kill off all my background jobs when I logout? 3.18. How do I list all my history entries? 3.19. How does the alternative loop syntax, e.g. `while {...} {...}' work? 3.20. Why is my history not being saved? Chapter 4: The mysteries of completion 4.1. What is completion? 4.2. What sorts of things can be completed? 4.3. How does zsh deal with ambiguous completions? 4.4. How do I complete in the middle of words / just what's before the cursor? 4.5. How do I get started with programmable completion? 4.6. And if programmable completion isn't good enough? Chapter 5: The future of zsh 5.1. What bugs are currently known and unfixed? (Plus recent important changes) 5.2. Where do I report bugs, get more info / who's working on zsh? 5.3. What's on the wish-list? 5.4. Will zsh have problems in the year 2000? Acknowledgments Copyright --- End of Contents --- Chapter 1: Introducing zsh and how to install it 1.1: Sources of information Information on zsh is available via the World Wide Web. The URL is http://sunsite.auc.dk/zsh/ (note the change of address from the end of April 1998). The server provides this FAQ and much else and is now maintained by Karsten Thygesen and others (mail zsh@sunsite.auc.dk with any related messages). The FAQ is at http://sunsite.auc.dk/zsh/FAQ/ . The site also contains some contributed zsh scripts and functions; we are delighted to add more, or simply links to your own collection. This document was originally written in YODL, allowing it to be converted easily into various other formats. The master source file lives at http://sunsite.auc.dk/zsh/FAQ/zshfaq.yo . Another useful source of information is the collection of FAQ articles posted frequently to the Usenet news groups comp.unix.questions, comp.unix.shells and comp.answers with answers to general questions about UNIX. The fifth of the seven articles deals with shells, including zsh, with a brief description of differences. (This article also talks about shell startup files which would otherwise rate a mention here.) There is also a separate FAQ on shell differences and how to change your shell. Usenet FAQs are available via FTP from rtfm.mit.edu and mirrors and also on the World Wide Web; see USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html The latest version of this FAQ is also available directly from any of the zsh archive sites listed in question 1.6. There is now a preliminary version of a reference card for zsh 3.0, which you can find (while it's being developed) at http://www.ifh.de/~pws/computing/refcard.ps This is optimised for A4 paper. The LaTeX source is in the same place with the extension .tex. It is not a good place from which to learn zsh for the first time. (As a method of reading the following in Emacs, you can type \M-2 \C-x $ to make all the indented text vanish, then \M-0 \C-x $ when you are on the title you want.) For any more eclectic information, you should contact the mailing list: see question 5.2. 1.2: What is it? Zsh is a UNIX command interpreter (shell) which of the standard shells most resembles the Korn shell (ksh); its compatibility with the 1988 Korn shell has been gradually increasing. It includes enhancements of many types, notably in the command-line editor, options for customising its behaviour, filename globbing, features to make C-shell (csh) users feel more at home and extra features drawn from tcsh (another `custom' shell). It was written by Paul Falstad when a student at Princeton; however, Paul doesn't maintain it any more and enquiries should be sent to the mailing list (see question 5.2). Zsh is distributed under a standard Berkeley style copyright. For more information, the files Doc/intro.txt or Doc/intro.troff included with the source distribution are highly recommended. A list of features is given in FEATURES, also with the source. 1.3: What is it good at? Here are some things that zsh is particularly good at. No claim of exclusivity is made, especially as shells copy one another, though in the areas of command line editing and globbing zsh is well ahead of the competition. I am not aware of a major interactive feature in any other freely-available shell which zsh does not also have (except smallness). o Command line editing: o programmable completion: incorporates the ability to use the full power of zsh globbing (compctl -g), o multi-line commands editable as a single buffer (even files!), o variable editing (vared), o command buffer stack, o print text straight into the buffer for immediate editing (print -z), o execution of unbound commands, o menu completion, o variable, editing function and option name completion, o inline expansion of variables, history commands. o Globbing --- extremely powerful, including: o recursive globbing (cf. find), o file attribute qualifiers (size, type, etc. also cf. find), o full alternation and negation of patterns. o Handling of multiple redirections (simpler than tee). o Large number of options for tailoring. o Path expansion (=foo -> /usr/bin/foo). o Adaptable messages for spelling, watch, time as well as prompt (including conditional expressions). o Named directories. o Comprehensive integer arithmetic. o Manipulation of arrays (including reverse subscripting). o Spelling correction. 1.4: On what machines will it run? From version 3.0, zsh uses GNU autoconf as the installation mechanism. This considerably increases flexibility over the old `buildzsh' mechanism. Consequently, zsh should compile and run on any modern version of UNIX, and a great many not-so-modern versions too. The file Etc/MACHINES in the distribution has more details. There are also now separate ports for Windows and OS/2, see `Where do I get it' below. If you need to change something to support a new machine, it would be appreciated if you could add any necessary preprocessor code and alter configure.in and config.h.in to configure zsh automatically, then send the required context diffs to the list (see question 5.2). Changes based on version 2.5 are very unlikely to be useful. To get it to work, retrieve the source distribution (see question 1.6), un-gzip it, un-tar it and read the INSTALL file in the top directory. Also read the Etc/MACHINES file for up-to-date information on compilation on certain architectures. *Note for users of nawk* (The following information comes from Zoltan Hidvegi): On some systems nawk is broken and produces an incorrect signames.h file. This makes the signals code unusable. This often happens on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems. 1.5: What's the latest version? Zsh 3.0.5 is the latest production version. The new major number 3.0 largely reflects the considerable internal changes in zsh to make it more reliable, consistent and (where possible) compatible. Those planning on upgrading their zsh installation should take a look at the list of incompatibilities at the end of 5.1. This is longer than usual due to enhanced sh, ksh and POSIX compatibility. The beta version 3.1.4 is also available. Development of zsh is usually patch by patch, with each intermediate version publicly available. Note that this `open' development system does mean bugs are sometimes introduced into the most recent archived version. These are usually fixed quickly. Note also that as the shell changes, it may become incompatible with older versions; see the end of question 5.1 for a partial list. Changes of this kind are almost always forced by an awkward or unnecessary feature in the original design (as perceived by current users), or to enhance compatibility with other Bourne shell derivatives, or (most recently) to provide POSIX compliancy. 1.6: Where do I get it? The archive is now run by Andrew Main <zefram@tao.co.uk>. The following are known mirrors (kept frequently up to date); the first is the official archive site, currently in Australia. All are available by anonymous FTP. The major sites keep test versions in the 'testing' subdirectory: such up-to-the-minute development versions should only be retrieved if you actually plan to help test the latest version of the shell. The following list also appears on the WWW at http://www.zsh.org . Home site ftp://ftp.zsh.org Australia ftp://ftp.ips.gov.au/mirror/zsh/ Denmark ftp://sunsite.auc.dk/pub/unix/shells/zsh Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/ France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/ Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/ ftp://ftp.gmd.de/packages/zsh/ ftp://ftp.uni-trier.de/pub/unix/shell/zsh/ Hungary ftp://ftp.cs.elte.hu/pub/zsh/ (also http://www.cs.elte.hu/pub/zsh/ ) Israel ftp://ftp.math.technion.ac.il/mirror/ftp.zsh.org/pub/zsh/ http://www.math.technion.ac.il/mirror/ftp.zsh.org/pub/zsh/ Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/ ftp://ftp.nis.co.jp/pub/shells/zsh/ Norway ftp://ftp.uit.no/pub/unix/shells/zsh/ Romania ftp://ftp.roedu.net/pub/mirrors/ftp.zsh.org/pub/zsh/ Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/ Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/ UK ftp://ftp.net.lut.ac.uk/zsh/ (also by FSP at port 21) ftp://src.doc.ic.ac.uk/packages/unix/shells/zsh/ USA ftp://ftp.math.gatech.edu/pub/zsh/ ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/ ftp://ftp.sterling.com/zsh/ ftp://ftp.rge.com/pub/shells/zsh/ The Windows port mentioned above is maintained separately by Amol Deshpande <amold@microsoft.com>; please mail Amol directly about any Windows-specific problems. This is quite new, so don't expect it to be perfect. You can get it from: ftp://ftp.blarg.net/users/amol/zsh Likewise the OS/2 port is available from TAMURA Kent <kent@tril.ibm.co.jp> at http://cgi.din.or.jp/~tkent/tmp/zsh-3.0.0-os2-a01.zip Starting from mid-October 1997, there is an archive of patches sent to the maintainers' mailing list. Note that these may not all be added to the shell, and some may already have been; you simply have to search for something you might want which is not in the version you have. Also, there may be some prerequisites earlier in the archive. It can be found on the zsh WWW pages (as described in 1.1) at: http://sunsite.auc.dk/zsh/Patches/ 1.7: I don't have root access: how do I make zsh my login shell? Unfortunately, on many machines you can't use `chsh' to change your shell unless the name of the shell is contained in /etc/shells, so if you have your own copy of zsh you need some sleight-of-hand to use it when you log on. (Simply typing `zsh' is not really a solution since you still have your original login shell waiting for when you exit.) The basic idea is to use `exec <zsh-path>' to replace the current shell with zsh. Often you can do this in a login file such as .profile (if your shell is sh or ksh) or .login (if it's csh). Make sure you have some way of altering the file (e.g. via FTP) before you try this as `exec' is often rather unforgiving. If you have zsh in a subdirectory `bin' of your home directory, put this in .profile: [ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l or if your login shell is csh or tcsh, put this in .login: if ( -f ~/bin/zsh ) exec ~/bin/zsh -l (in each case the `-l' tells zsh it is a login shell). If you want to check this works before committing yourself to it, you can make the login shell ask whether to exec zsh. The following work for Bourne-like shells: [ -f $HOME/bin/zsh ] && { echo "Type Y to run zsh: \c" read line [ "$line" = Y ] && exec $HOME/bin/zsh -l } and for C-shell-like shells: if ( -f ~/bin/zsh ) then echo -n "Type Y to run zsh: " if ( "$<" == Y ) exec ~/bin/zsh -l endif It's not a good idea to put this (even without the -l) into .cshrc, at least without some tests on what the csh is supposed to be doing, as that will cause _every_ instance of csh to turn into a zsh and will cause csh scripts (yes, unfortunately some people write these) which do not call `csh -f' to fail. If you want to tell xterm to run zsh, change the SHELL environment variable to the full path of zsh at the same time as you exec zsh (in fact, this is sensible for consistency even if you aren't using xterm). If you have to exec zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec zsh'. If you like your login shell to appear in the process list as `-zsh', you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh ~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure `-zsh' is in your path.) This has the same effect as the `-l' option. Footnote: if you DO have root access, make sure zsh goes in /etc/shells on all appropriate machines, including NIS clients, or you may have problems with FTP to that machine. Chapter 2: How does zsh differ from...? As has already been mentioned, zsh is most similar to ksh, while many of the additions are to please csh users. Here are some more detailed notes. See also the article `UNIX shell differences and how to change your shell' posted frequently to the USENET group comp.unix.shell. 2.1: Differences from sh and ksh Most features of ksh (and hence also of sh) are implemented in zsh; problems can arise because the implementation is slightly different. Note also that not all ksh's are the same either. I have based this on the 11/16/88f version of ksh; differences from ksh93 will be more substantial. As a summary of the status: 1) because of all the options it is not safe to assume a general zsh run by a user will behave as if sh or ksh compatible; 2) invoking zsh as sh or ksh (or if either is a symbolic link to zsh) sets appropriate options and improves compatibility (from within zsh itself, calling `ARGV0=sh zsh' will also work); 3) from version 3.0 onward the degree of compatibility with sh under these circumstances is very high: zsh can now be used with GNU configure or perl's Configure, for example; 4) the degree of compatibility with ksh is also high, but a few things are missing: for example the more sophisticated pattern-matching expressions are different for versions before 3.1.3 --- see the detailed list below; 5) also from 3.0, the command `emulate' is available: `emulate ksh' and `emulate sh' set various options as well as changing the effect of single-letter option flags as if the shell had been invoked with the appropriate name. Including the commands `emulate sh; setopt localoptions' in a shell function will turn on sh emulation for that function only. The classic difference is word splitting, discussed in 3.1; this catches out very many beginning zsh users. As explained there, this is actually a bug in every other shell. The answer is to set SH_WORD_SPLIT for backward compatibility. The next most classic difference is that unmatched glob patterns cause the command to abort; set NO_NOMATCH for those. Here is a list of various options which will increase ksh compatibility, though maybe decrease zsh's abilities: see the manual entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs in some versions of ksh), KSH_ARRAYS, KSH_GLOB, KSH_OPTION_PRINT, LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP, NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT, POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS, SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE. Note that you can also disable any built-in commands which get in your way. If invoked as `ksh', the shell will try and set suitable options. Here are some differences from ksh which might prove significant for ksh programmers, some of which may be interpreted as bugs; there must be more. Note that this list is deliberately rather full and that most of the items are fairly minor. Those marked `*' perform in a ksh-like manner if the shell is invoked with the name `ksh', or if `emulate ksh' is in effect. Capitalised words with underlines refer to shell options. o Syntax: o * Shell word splitting: see question 3.1. o * Arrays are (by default) more csh-like than ksh-like: subscripts start at 1, not 0; array[0] refers to array[1]; `$array' refers to the whole array, not $array[0]; braces are unnecessary: $a[1] == ${a[1]}, etc. The KSH_ARRAYS option is now available. o Coprocesses are established by `coproc'; `|&' behaves like csh. Handling of coprocess file descriptors is also different. o In `cmd1 && cmd2 &', only `cmd2' instead of the whole expression is run in the background in zsh. The manual implies this is a bug. Use `{ cmd1 && cmd2 } &' as a workaround. o Command line substitutions, globbing etc.: o * Failure to match a globbing pattern causes an error (use NO_NOMATCH). o * The results of parameter substitutions are treated as plain text: `foo="*"; print $foo' prints all files in ksh but `*' in zsh. (GLOB_SUBST has been added to fix this.) o The backslash in $(echo '\$x') is treated differently: in ksh, it is not stripped, in zsh it is. (The `...` form gives the same in both shells.) o * $PSn do not do parameter substitution by default (use PROMPT_SUBST). o * Standard globbing does not allow ksh-style `pattern-lists'. Equivalents: ---------------------------------------------------------------------- ksh zsh Meaning ----- ----- --------- !(foo) ^foo Anything but foo. or foo1~foo2 Anything matching foo1 but foo2[1]. @(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ... ?(foo) (foo|) Zero or one occurrences of foo. *(foo) (foo)# Zero or more occurrences of foo. +(foo) (foo)## One or more occurrences of foo. ---------------------------------------------------------------------- The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB. From version 3.1.3, the ksh forms are fully supported when the option KSH_GLOB is in effect; for previous versions you must use the table above. [1] Note that `~' is the only globbing operator to have a lower precedence than `/'. For example, `**/foo~*bar*' matches any file in a subdirectory called `foo', except where `bar' occurred somewhere in the path (e.g. `users/barstaff/foo' will be excluded by the `~' operator). As the `**' operator cannot be grouped (inside parentheses it is treated as `*'), this is the way to exclude some subdirectories from matching a `**'. o Unquoted assignments do file expansion after `:'s (intended for PATHs). o `integer' does not allow `-i'. o `typeset' and `integer' have special behaviour for assignments in ksh, but not in zsh. For example, this doesn't work in zsh: integer k=$(wc -l ~/.zshrc) because the return value from wc includes leading whitespace which causes wordsplitting. Ksh handles the assignment specially as a single word. o Command execution: o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc; note also $ZDOTDIR). o $PATH is not searched for commands specified at invocation without -c. o Aliases and functions: o The order in which aliases and functions are defined is significant: function definitions with () expand aliases -- see question 2.3. o Aliases and functions cannot be exported. o There are no tracked aliases: command hashing replaces these. o The use of aliases for key bindings is replaced by `bindkey'. o * Options are not local to functions (use LOCAL_OPTIONS; note this may always be unset locally to propagate options settings from a function to the calling level). o Traps and signals: o Traps are not local to functions. o TRAPERR has become TRAPZERR (this was forced by UNICOS which has SIGERR). o Editing: o The options emacs, gmacs, viraw are not supported. Use bindkey to change the editing behaviour: `set -o {emacs,vi}' becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use `bindkey \^t gosmacs-transpose-characters'. o The `keyword' option does not exist and `-k' is instead interactivecomments. (`keyword' will not be in the next ksh release either.) o Management of histories in multiple shells is different: the history list is not saved and restored after each command. o `\' does not escape editing chars (use `^V'). o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q'). o * `#' in an interactive shell is not treated as a comment by default. o Built-in commands: o Some built-ins (r, autoload, history, integer ...) were aliases in ksh. o There is no built-in command newgrp: use e.g. `alias newgrp="exec newgrp"' o `jobs' has no `-n' flag. o `read' has no `-s' flag. o Other idiosyncrasies: o `select' always redisplays the list of selections on each loop. 2.2: Similarities with csh Although certain features aim to ease the withdrawal symptoms of csh (ab)users, the syntax is in general rather different and you should certainly not try to run scripts without modification. The c2z script is provided with the source (in Misc/c2z) to help convert .cshrc and .login files; see also the next question concerning aliases, particularly those with arguments. Csh-compatibility additions include: o logout, rehash, source, (un)limit built-in commands. o *rc file for interactive shells. o Directory stacks. o cshjunkie*, ignoreeof options. o The CSH_NULL_GLOB option. o >&, |& etc. redirection. (Note that `>file 2>&1' is the standard Bourne shell command for csh's `>&file'.) o foreach ... loops; alternative syntax for other loops. o Alternative syntax `if ( ... ) ...', though this still doesn't work like csh: it expects a command in the parentheses. Also `for', `which'. o $PROMPT as well as $PS1, $status as well as $?, $#argv as well as $#, .... o Escape sequences via % for prompts. o Special array variables $PATH etc. are colon-separated, $path are arrays. o !-type history (which may be turned off via `setopt nobanghist'). o Arrays have csh-like features (see under 2.1). 2.3: Why do my csh aliases not work? (Plus other alias pitfalls.) First of all, check you are using the syntax alias newcmd='list of commands' and not alias newcmd 'list of commands' which won't work. (It tells you if `newcmd' and `list of commands' are already defined as aliases.) Otherwise, your aliases probably contain references to the command line of the form `\!*', etc. Zsh does not handle this behaviour as it has shell functions which provide a way of solving this problem more consistent with other forms of argument handling. For example, the csh alias alias cd 'cd \!*; echo $cwd' can be replaced by the zsh function, cd() { builtin cd $*; echo $PWD; } (the `builtin' tells zsh to use its own `cd', avoiding an infinite loop) or, perhaps better, cd() { builtin cd $*; print -D $PWD; } (which converts your home directory to a ~). In fact, this problem is better solved by defining the special function chpwd() (see the manual). Note also that the `;' at the end of the function is optional in zsh, but not in ksh or sh (for sh's where it exists). Here is Bart Schaefer's guide to converting csh aliases for zsh. 1) If the csh alias references "parameters" (\!:1, \!* etc.), then in zsh you need a function (referencing $1, $* etc.). Otherwise, you can use a zsh alias. 2) If you use a zsh function, you need to refer _at_least_ to $* in the body (inside the { }). Parameters don't magically appear inside the { } the way they get appended to an alias. 3) If the csh alias references its own name (alias rm "rm -i"), then in a zsh function you need the "command" keyword (function rm() { command rm -i $* }), but in a zsh alias you don't (alias rm="rm -i"). 4) If you have aliases that refer to each other (alias ls "ls -C"; alias lf "ls -F" ==> lf == ls -C -F) then you must either: o convert all of them to zsh functions; or o after converting, be sure your .zshrc defines all of your aliases before it defines any of your functions. Those first four are all you really need, but here are four more for heavy csh alias junkies: 5) Mapping from csh alias "parameter referencing" into zsh function (assuming shwordsplit and ksharrays are NOT set in zsh): csh zsh ===== ========== \!* $* (or $argv) \!^ $1 (or $argv[1]) \!:1 $1 \!:2 $2 (or $argv[2], etc.) \!$ $*[$#] (or $argv[$#], or $*[-1]) \!:1-4 $*[1,4] \!:1- $*[1,$#-1] (or $*[1,-2]) \!^- $*[1,$#-1] \!*:q "$@" ($*:q doesn't work (yet)) \!*:x $=* ($*:x doesn't work (yet)) 6) Remember that it is NOT a syntax error in a zsh function to refer to a position ($1, $2, etc.) greater than the number of parameters. (E.g., in a csh alias, a reference to \!:5 will cause an error if 4 or fewer arguments are given; in a zsh function, $5 is the empty string if there are 4 or fewer parameters.) 7) To begin a zsh alias with a - (dash, hyphen) character, use `alias --': csh zsh =============== ================== alias - "fg %-" alias -- -="fg %-" 8) Stay away from `alias -g' in zsh until you REALLY know what you're doing. There is one other serious problem with aliases: consider alias l='/bin/ls -F' l() { /bin/ls -la $* | more } `l' in the function definition is in command position and is expanded as an alias, defining `/bin/ls' and `-F' as functions which call `/bin/ls', which gets a bit recursive. This can be avoided if you use `function' to define a function, which doesn't expand aliases. It is possible to argue for extra warnings somewhere in this mess. Luckily, it is not possible to define `function' as an alias. Bart Schaefer's rule is: Define first those aliases you expect to use in the body of a function, but define the function first if the alias has the same name as the function. 2.4: Similarities with tcsh (The sections on csh apply too, of course.) Certain features have been borrowed from tcsh, including $watch, run-help, $savehist, $histlit, periodic commands etc., extended prompts, sched and which built-ins. Programmable completion was inspired by, but is entirely different to, tcsh's `complete'. (There is a perl script called lete2ctl in the Misc directory of the source distribution to convert `complete' to `compctl' statements.) This list is not definitive: some features have gone in the other direction. If you're missing the editor function run-fg-editor, try something with `bindkey -s' (which binds a string to a keystroke), e.g. bindkey -s '^z' '\eqfg %$EDITOR:t\n' which pushes the current line onto the stack and tries to bring a job with the basename of your editor into the foreground. `bindkey -s' allows limitless possibilities along these lines. You can execute any command in the middle of editing a line in the same way, corresponding to tcsh's `-c' option: bindkey -s '^p' '\eqpwd\n' In both these examples, the `\eq' saves the current input line to be restored after the command runs; a better effect with multiline buffers is achieved if you also have bindkey '\eq' push-input to save the entire buffer. 2.5: Similarities with bash The Bourne-Again Shell, bash, is another enhanced Bourne-like shell; the most obvious difference from zsh is that it does not attempt to emulate the Korn shell. Since both shells are under active development it is probably not sensible to be too specific here. Broadly, bash has paid more attention to standards compliancy (i.e. POSIX) for longer, and has so far avoided the more abstruse interactive features (programmable completion, etc.) that zsh has. 2.6: Shouldn't zsh be more/less like ksh/(t)csh? People often ask why zsh has all these `unnecessary' csh-like features, or alternatively why zsh doesn't understand more csh syntax. This is far from a definitive answer and the debate will no doubt continue. Paul's object in writing zsh was to produce a ksh-like shell which would have features familiar to csh users. For a long time, csh was the preferred interactive shell and there is a strong resistance to changing to something unfamiliar, hence the additional syntax and CSH_JUNKIE options. This argument still holds. On the other hand, the arguments for having what is close to a plug-in replacement for ksh are, if anything, even more powerful: the deficiencies of csh as a programming language are well known (look in any Usenet FAQ archive, e.g. http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\ shell/csh-whynot/faq.html if you are in any doubt) and zsh is able to run many standard scripts such as /etc/rc. Of course, this makes zsh rather large and feature-ridden so that it seems to appeal mainly to hackers. The only answer, perhaps not entirely satisfactory, is that you have to ignore the bits you don't want. The introduction of loadable in modules in version 3.1 should help. Chapter 3: How to get various things to work 3.1: Why does `$var' where `var="foo bar"' not do what I expect? In most Bourne-shell derivatives, multiple-word variables such as var="foo bar" are split into words when passed to a command or used in a `for foo in $var' loop. By default, zsh does not have that behaviour: the variable remains intact. (This is not a bug! See below.) An option (SHWORDSPLIT) exists to provide compatibility. For example, defining the function args to show the number of its arguments: args() { echo $#; } and with our definition of `var', args $var produces the output `1'. After setopt shwordsplit the same function produces the output `2', as with sh and ksh. Unless you need strict sh/ksh compatibility, you should ask yourself whether you really want this behaviour, as it can produce unexpected effects for variables with entirely innocuous embedded spaces. This can cause horrendous quoting problems when invoking scripts from other shells. The natural way to produce word-splitting behaviour in zsh is via arrays. For example, set -A array one two three twenty (or array=(one two three twenty) if you prefer), followed by args $array produces the output `4', regardless of the setting of SHWORDSPLIT. Arrays are also much more versatile than single strings. Probably if this mechanism had always been available there would never have been automatic word splitting in scalars, which is a sort of uncontrollable poor man's array. Note that this happens regardless of the value of the internal field separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo' you get the answer 1. Other ways of causing word splitting include a judicious use of `eval': sentence="Longtemps, je me suis couch\\'e de bonne heure." eval "words=($sentence)" after which $words is an array with the words of $sentence (note characters special to the shell, such as the `'' in this example, must already be quoted), or, less standard but more reliable, turning on SHWORDSPLIT for one variable only: args ${=sentence} always returns 8 with the above definition of `args'. (In older versions of zsh, ${=foo} toggled SHWORDSPLIT; now it forces it on.) Note also the "$@" method of word splitting is always available in zsh functions and scripts (though strictly this does array splitting, not word splitting). SHWORDSPLIT is set when zsh is invoked with the names `ksh' or `sh', or (entirely equivalent) when `emulate ksh' or `emulate sh' is in effect. 3.2: What is the difference between `export' and the ALL_EXPORT option? Normally, you would put a variable into the environment by using `export var'. The command `setopt allexport' causes all variables which are subsequently set (N.B. not all the ones which already exist) to be put into the environment. This may seem a useful shorthand, but in practice it can have unhelpful side effects: 1) Since every variable is in the environment as well as remembered by the shell, the memory for it needs to be allocated twice. This is bigger as well as slower. 2) It really is *every* variable which is exported, even loop variables in `for' loops. This is probably a waste. 3) An arbitrary variable created by the user might have a special meaning to a command. Since all shell variables are visible to commands, there is no protection against this. For these reasons it is usually best to avoid ALL_EXPORT unless you have a specific use for it. One safe use is to set it before creating a list of variables in an initialisation file, then unset it immediately afterwards. Only those variables will be automatically exported. 3.3: How do I turn off spelling correction/globbing for a single command? In the first case, you presumably have `setopt correctall' in an initialisation file, so that zsh checks the spelling of each word in the command line. You probably do not want this behaviour for commands which do not operate on existing files. The answer is to alias the offending command to itself with `nocorrect' stuck on the front, e.g. alias mkdir='nocorrect mkdir' To turn off globbing, the rationale is identical: alias mkdir='noglob mkdir' You can have both nocorrect and noglob, if you like, but the nocorrect must come first, since it is needed by the line editor, while noglob is only handled when the command is examined. Note also that a shell function won't work: the no... directives must be expanded before the rest of the command line is parsed. 3.4: How do I get the meta key to work on my xterm? As stated in the manual, zsh needs to be told about the meta key by using `bindkey -me' or `bindkey -mv' in your .zshrc or on the command line. You probably also need to tell the terminal driver to allow the `meta' bit of the character through; `stty pass8' is the usual incantation. Sample .zshrc entry: [[ $TERM = "xterm" ]] && stty pass8 && bindkey -me or, on SYSVR4-ish systems without pass8, [[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me (disable parity detection, don't strip high bit, use 8-bit characters). Make sure this comes _before_ any bindkey entries in your .zshrc which redefine keys normally defined in the emacs/vi keymap. You don't need the `bindkey' to be able to define your own sequences with the meta key, though you still need the `stty'. 3.5: How do I automatically display the directory in my xterm title bar? You should use the special function `chpwd', which is called when the directory changes. The following checks that standard output is a terminal, then puts the directory in the title bar if the terminal is an xterm or a sun-cmd. chpwd() { [[ -t 1 ]] || return case $TERM in sun-cmd) print -Pn "\e]l%~\e\\" ;; xterm) print -Pn "\e]2;%~\a" ;; esac } Change `%~' if you want the message to be different. (The `-P' option interprets such sequences just like in prompts, in this case producing the current directory; you can of course use `$PWD' here, but that won't use the `~' notation which I find clearer.) Note that when the xterm starts up you will probably want to call chpwd directly: just put `chpwd' in .zshrc after it is defined or autoloaded. 3.6: How do I make the completion list use eight bit characters? A traditional UNIX environment (character terminal and ASCII character sets) is not sufficient to be able to handle non-ASCII characters, and there are so many possible enhancements that in general this is hard. However, if you have something like an xterm using a standard character set like ISO-8859-1 (which is often the default for xterm), read on. You should also note question 3.4 on the subject of eight bit characters. You are probably creating files with names including non-ASCII accented characters, and find they show up in the completion list as \M-i or something such. This is because the library routines (not zsh itself) which test whether a character is printable have replied that it is not; zsh has simply found a way to show them anyway. The answer, under a modern POSIXy operating system, is to find a locale where these are treated as printable characters. Zsh has handling for locales built in and will recognise when you set a relevant variable. You need to look in /usr/lib/locale to find one which suits you; the subdirectories correspond to the locale names. The simplest possibility is likely to be en_US, so that the simplest answer to your problem is to set LC_CTYPE=en_US when your terminal is capable of showing eight bit characters. If you only have a default domain (called C), you may need to have some additional files installed on your system. 3.7: Why do the cursor (arrow) keys not work? The cursor keys send different codes depending on the terminal; zsh only binds the most well known versions. If you see these problems, try putting the following in your .zshrc: bindkey "$(echotc kl)" backward-char bindkey "$(echotc kr)" forward-char bindkey "$(echotc ku)" up-line-or-history bindkey "$(echotc kd)" down-line-or-history If you use vi mode, use `vi-backward-char' and `vi-forward-char' where appropriate. Note, however, that up to version 3.0 binding arbitrary multiple key sequences can cause problems, so check that this works with your set up first. Also, from version 3.1.3, more sequences are supported by default, namely those in the form `<ESC>O' followed by A, B, C or D, as well as the corresponding set beginning `<ESC>[', so this may be redundant. 3.8: Why does my terminal act funny in some way? If you are using an OpenWindows cmdtool as your terminal, any escape sequences (such as those produced by cursor keys) will be swallowed up and never reach zsh. Either use shelltool or avoid commands with escape sequences. You can also disable scrolling from the cmdtool pane menu (which effectively turns it into a shelltool). If you still want scrolling, try using an xterm with the scrollbar activated. If that's not the problem, and you are using stty to change some tty settings, make sure you haven't asked zsh to freeze the tty settings: type ttyctl -u before any stty commands you use. On the other hand, if you aren't using stty and have problems you may need the opposite: `ttyctl -f' freezes the terminal to protect it from hiccups introduced by other programmes (kermit has been known to do this). If _that_'s not the problem, and you are having difficulties with external commands (not part of zsh), and you think some terminal setting is wrong (e.g. ^V is getting interpreted as `literal next character' when you don't want it to be), try ttyctl -u STTY='lnext "^-"' commandname (in this example), or just export STTY for all commands to see. Note that zsh doesn't reset the terminal completely afterwards: just the modes it uses itself and a number of special processing characters (see the stty(1) manual page). At some point there may be an overhaul which allows the terminal modes used by the shell to be modified separately from those seen by external programmes. This is partially implemented already: from 2.5, the shell is less susceptible to mode changes inherited from programmes than it used to be. 3.9: Why does zsh not work in an Emacs shell mode any more? (This information comes from Bart Schaefer and other zsh-workers.) Emacs 19.29 or thereabouts stopped using a terminal type of "emacs" in shell buffers, and instead sets it to "dumb". Zsh only kicks in its special I'm-inside-emacs initialization when the terminal type is "emacs". Probably the most reliable way of dealing with this is to look for the environment variable `$EMACS', which is set to `t' in Emacs' shell mode. Putting [[ $EMACS = t ]] && unsetopt zle in your .zshrc should be sufficient. Another method is to put #!/bin/sh TERM=emacs exec zsh into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and tell emacs to use that as the shell by adding (setenv "ESHELL" "~/bin/eshell") to ~/.emacs. 3.10: Why do my autoloaded functions not autoload [the first time]? The problem is that there are two possible ways of autoloading a function (see the AUTOLOADING FUNCTIONS section of the zsh manual page zshmisc for more detailed information): 1) The file contains just the body of the function, i.e. there should be no line at the beginning saying `function foo {' or `foo () {', and consequently no matching `}' at the end. This is the traditional zsh method. The advantage is that the file is called exactly like a script, so can double as both. To define a function `xhead () { print -n "\033]2;$*\a"; }', the file would just contain `print -n "\033]2;$*\a"'. 2) The file contains the entire definition, and maybe even other code: it is run when the function needs to be loaded, then the function itself is called up. This is the method in ksh. To define the same function `xhead', the whole of the usual definition should be in the file. In old versions of zsh, before 3.0, only the first behaviour was allowed, so you had to make sure the file found for autoload just contained the function body. You could still define other functions in the file with the standard form for definitions, though they would be redefined each time you called the main function. In version 3.0.x, the second behaviour is activated if the file defines the autoloaded function. Unfortunately, this is incompatible with the old zsh behaviour which allowed you to redefine the function when you called it. From version 3.1, there is an option KSHAUTOLOAD to allow full ksh compatiblity, i.e. the function _must_ be in the second form above. If that is not set, zsh tries to guess which form you are using: if the file contains only a complete definition of the function in the second form, and nothing else apart from comments and whitespace, it will use the function defined in the file; otherwise, it will assume the old behaviour. The option is set if `emulate ksh' is in effect, of course. (A neat trick to autoload all functions in a given directory is to include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in parentheses removes the directory part of the filenames, leaving just the function names.) 3.11: How does base arithmetic work? The ksh syntax is now understood, i.e. let 'foo = 16#ff' or equivalently (( foo = 16#ff )) or even foo=$[16#ff] (note that `foo=$((16#ff))' is now supported). The original syntax was (( foo = [16]ff )) --- this was based on a misunderstanding of the ksh manual page. It still works but its use is deprecated. Then echo $foo gives the answer `255'. It is possible to declare variables explicitly to be integers, via typeset -i foo which has a different effect: namely the base used in the first assignment (hexadecimal in the example) is subsequently used whenever `foo' is displayed (although the internal representation is unchanged). To ensure foo is always displayed in decimal, declare it as typeset -i 10 foo which requests base 10 for output. You can change the output base of an existing variable in this fashion. Using the `$(( ... ))' method will always display in decimal. 3.12: How do I get a newline in my prompt? You can place a literal newline in quotes, i.e. PROMPT="Hi Joe, what now?%# " If you have the bad taste to set the option cshjunkiequotes, which inhibits such behaviour, you will have to bracket this with `unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it in your .zshrc before the option is set. Arguably the prompt code should handle `print'-like escapes. Feel free to write this :-). Otherwise, you can use PROMPT=$(print "Hi Joe,\nwhat now?%# ") in your initialisation file. 3.13: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny? You probably have the extendedglob option set in which case ^ and # are metacharacters. ^a matches any file except one called a, so the line is interpreted as bindkey followed by a list of files. Quote the ^ with a backslash or put quotation marks around ^a. 3.14: Why can't I bind \C-s and \C-q any more? The control-s and control-q keys now do flow control by default, unless you have turned this off with `stty -ixon' or redefined the keys which control it with `stty start' or `stty stop'. (This is done by the system, not zsh; the shell simply respects these settings.) In other words, \C-s stops all output to the terminal, while \C-q resumes it. There is an option NO_FLOW_CONTROL to stop zsh from allowing flow control and hence restoring the use of the keys: put `setopt noflowcontrol' in your .zshrc file. 3.15: How do I execute command `foo' within function `foo'? The command `command foo' does just that. You don't need this with aliases, but you do with functions. Note that error messages like zsh: job table full or recursion limit exceeded are a good sign that you tried calling `foo' in function `foo' without using `command'. If `foo' is a builtin rather than an external command, use `builtin foo' instead. 3.16: Why do history substitutions with single bangs do something funny? If you have a command like "echo !-2:$ !$", the first history substitution then sets a default to which later history substitutions with single unqualified bangs refer, so that !$ becomes equivalent to !-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer to the last command. 3.17: Why does zsh kill off all my background jobs when I logout? Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives you the option of having background jobs killed or not: the `nohup' option exists if you don't want them killed. Note that you can always run programs with `nohup' in front of the pipeline whether or not the option is set, which will prevent that job from being killed on logout. (`nohup' is actually an external command.) The `disown' builtin is very useful in this respect: if zsh informs you that you have background jobs when you try to logout, you can `disown' all the ones you don't want killed when you exit. This is also a good way of making jobs you don't need the shell to know about (such as commands which create new windows) invisible to the shell. Likewise, you can start a background job with `&!' instead of just `&' at the end, which will automatically disown the job. 3.18: How do I list all my history entries? Tell zsh to start from entry 1: `history 1'. Those entries at the start which are no longer in memory will be silently omitted. 3.19: How does the alternative loop syntax, e.g. `while {...} {...}' work? Zsh provides an alternative to the traditional sh-like forms with `do', while TEST; do COMMANDS; done allowing you to have the COMMANDS delimited with some other command structure, often `{...}'. The rules are quite complicated and in most scripts it is probably safer --- and certainly more compatible --- to stick with the sh-like rules. If you are wondering, the following is a rough guide. To make it work you must make sure the TEST itself is clearly delimited. For example, this works: while (( i++ < 10 )) { echo i is $i; } but this does _not_: while let "i++ < 10"; { echo i is $i; } # Wrong! The reason is that after `while', any sort of command list is valid. This includes the whole list `let "i++ < 10"; { echo i $i; }'; the parser simply doesn't know when to stop. Furthermore, it is wrong to miss out the semicolon, as this makes the `{...}' part of the argument to `let'. A newline behaves the same as a semicolon, so you can't put the brace on the next line as in C. So when using this syntax, the test following the `while' must be wrapped up: any of `((...))', `[[...]]', `{...}' or `(...)' will have this effect. (They have their usual syntactic meanings too, of course; they are not interchangeable.) Note that here too it is wrong to put in the semicolon, as then the case becomes identical to the preceding one: while (( i++ < 10 )); { echo i is $i; } # Wrong! The same is true of the `if' and `until' constructs: if { true } { echo yes } else { echo no } but with `for', which only needs a list of words, you can get away with it: for foo in a b; { echo foo is $a; bar=$foo; } since the parser knows it only needs everything up to the first semicolon. For the same reason, there is no problem with the `repeat', `case' or `select' constructs; in fact, `repeat' doesn't even need the semicolon since it knows the repeat count is just one word. This is independent of the behaviour of the SHORTLOOPS option (see manual), which you are in any case encouraged even more strongly not to use in programs as it can be very confusing. 3.20: Why is my history not being saved? In zsh, you need to set three variables to make sure your history is written out when the shell exits. For example, HISTSIZE=200 HISTFILE=~/.zsh_history SAVEHIST=200 $HISTSIZE tells the shell how many lines to keep internally, $HISTFILE tells it where to write the history, and $SAVEHIST, the easiest one to forget, tells it how many to write out. The simplest possibility is to set it to the same as $HISTSIZE as above. There are also various options affecting history; see the manual. Chapter 4: The mysteries of completion Programmable completion using the `compctl' command is one of the most powerful, and also potentially confusing, features of zsh; here I give a short introduction. There is a set of example completions supplied with the source in Misc/compctl-examples; completion definitions for many of the most obvious commands can be found there. 4.1: What is completion? `Completion' is where you hit a particular command key (TAB is the standard one) and the shell tries to guess the word you are typing and finish it for you --- a godsend for long file names, in particular, but in zsh there are many, many more possibilities than that. There is also a related process, `expansion', where the shell sees you have typed something which would be turned by the shell into something else, such as a variable turning into its value ($PWD becomes /home/users/mydir) or a history reference (!! becomes everything on the last command line). In zsh, when you hit TAB it will look to see if there is an expansion to be done; if there is, it does that, otherwise it tries to perform completion. (You can see if the word would be expanded --- not completed --- by TAB by typing `\C-x g', which lists expansions.) Expansion is generally fairly intuitive and not under user control; for the rest of the chapter I will discuss completion only. 4.2: What sorts of things can be completed? The simplest sort is filename completion, mentioned above. Unless you have made special arrangements, as described below, then after you type a command name, anything else you type is assumed by the completion system to be a filename. If you type part of a word and hit TAB, zsh will see if it matches the first part a file name and if it does it will automatically insert the rest. The other simple type is command completion, which applies (naturally) to the first word on the line. In this case, zsh assumes the word is some command to be executed lying in your $PATH (or something else you can execute, like a builtin command, a function or an alias) and tries to complete that. Other forms of completion have to be set up by special arrangement. See the manual entry for compctl for a list of all the flags: you can make commands complete variable names, user names, job names, etc., etc. For example, one common use is that you have an array variable, $hosts, which contains names of other machines you use frequently on the network: hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu) then you can tell zsh that when you use telnet (or ftp, or ...), the argument will be one of those names: compctl -k hosts telnet ftp ... so that if you type `telnet fr' and hit TAB, the rest of the name will appear by itself. An even more powerful option to compctl (-g) is to tell zsh that only certain sorts of filename are allowed. The argument to -g is exactly like a glob pattern, with the usual wildcards `*', `?', etc. In the compctl statement it needs to be quoted to avoid it being turned into filenames straight away. For example, compctl -g '*.(ps|eps)' ghostview tells zsh that if you type TAB on an argument after a ghostview command, only files ending in `.ps' or `.eps' should be considered for completion. A useful addition for zsh from version 3.1 is directory completion: compctl -/ cd Before, you had to use -g, but this is neater: it takes care of things like ignoring directories beginning with a dot unless you've typed the dot yourself, and whole directory paths are understood. Note that flags may be combined; if you have more than one, all the possible completions for all of them are put into the same list, all of them being possible completions. So compctl -k hosts -f rcp tells zsh that rcp can have a hostname or a filename after it. (You really need to be able to handle host:file, which is where programmable completion comes in, see 4.5.) Also, from version 3.1 you can always handle directories at the same time as other files just by adding -/ to the list. 4.3: How does zsh deal with ambiguous completions? Often there will be more than one possible completion: two files start with the same characters, for example. Zsh has a lot of flexibility for what it does here via its options. The default is for it to beep and completion to stop until you type another character. You can type \C-D to see all the possible completions. (That's assuming your at the end of the line, otherwise \C-D will delete the next character and you have to use ESC-\C-D.) This can be changed by the following options, among others: o with nobeep set, that annoying beep goes away o with nolistbeep, beeping is only turned off for ambiguous completions o with autolist set, when the completion is ambiguous you get a list without having to type \C-D o with listambigous, this is modified so that nothing is listed if there is an unambiguous prefix or suffix to be inserted o with menucomplete set, one completion is always inserted completely, then when you hit TAB it changes to the next, and so on until you get back to where you started o with automenu, you only get the menu behaviour when you hit TAB again on the ambiguous completion. o Finally, although it affects all completion lists, including those explicitly requested, note also alwayslastprompt, which causes the cursor to return to the line you were editing after printing the list, provided that is short enough. Combinations of these are possible; for example, autolist and automenu together give an intuitive combination. Note that from version 3.1 listambiguous is set by default; if you use autolist, you may well want to `unsetopt listambiguous'. 4.4: How do I complete in the middle of words / just what's before the cursor? Sometimes you have a word on the command-line (let's stick to file names) which is incomplete in the middle. Normally if you hit tab in zsh, it will simply go to the end of the word and try to complete there. However, there are two ways of changing this. First, there is the option COMPLETE_IN_WORD. This tries to fill in the word at the point of the cursor. For example, if the current directory contains `foobar', then with the option set, you can complete `fbar' to `foobar' by moving the cursor to the `b' and hitting tab. That's not the full story, however. Sometimes you just want the part of the word before the cursor completed. For example, the word is `/usr/loc/b', which you want to complete to `/usr/local/bin'. Normally, zsh won't do this in one go because there are two bits missing (but see below!), so you need to complete the `/usr/loc' on its own first. For this you need the function expand-or-complete-prefix: it works mostly like the usual function bound to tab, but it ignores anything on the right of the cursor. If you always want this behaviour (some other shells do this), bind it to tab; otherwise put another binding, e.g. `^X TAB' in ~/.zshrc: bindkey "^X^I" expand-or-complete-prefix then in the example you can move to just after `/usr/loc', hit whatever key you've just bound, move to the end, and hit tab. (Note that AUTO_REMOVE_SLASH behaviour applies here, see the manual.) Even that doesn't exhaust the possibilities. Included with the source distribution is the file Functions/multicomp, a function which you can bind as an alternative form of default completion (see below for a description of alternative completion), e.g. compctl -D -f + -U -Q -K multicomp and whole sequences of directories, like `/usr/loc/b' or even `/u/l/b' can be completed in one go. It works best with menucompletion if the result is ambiguous. 4.5: How do I get started with programmable completion? Finally, the hairiest part of completion. It is possible to get zsh to consider different completions not only for different commands, but for different words of the same command, or even to look at other words on the command line (for example, if the last word was a particular flag) and decide then. There are really two sorts of things to worry about. The simpler is alternative completion: that just means zsh will try one alternative, and only if there are no possible completions try the next. For example compctl -g '*.ps' + -f lpr says that after lpr you'd prefer to find only `.ps' files, so if there are any, only those are used, but if there aren't any, any old file is a possibility. You can also have a + with no flags after it, which tells zsh that it's to treat the command like any other if nothing was found. That's only really useful if your default completion is fancy, i.e. you have done something with `compctl -D' to tell zsh how commands which aren't specially handled are to have their arguments completed. The second sort is the hard one. Following a `-x', zsh expects that the next thing will be some completion code, which is a single letter followed by an argument in square brackets. For example `p[1]': `p' is for position, and the argument tells it to look at position 1; that says that this completion only applies to the word immediately after the command. You can also say `p[1,3]' which says the completion only applies to the word if it's between the first and third words, inclusive, after the command, and so on. See the list in the `compctl' manual entry for a list of these conditions: some conditions take one argument in the square brackets, some two. Usually, negative numeric arguments count backwards from the end (for example, `p[-1]' applies to the last word on the line). (Note the difference in the ways `+' and `-x' work. A `+' completion will always try and find completions for what's before the `+' first; it will only produce a list for what's after if the first list was empty. On the other hand, if a condition for a `-x' matches, the appropriate set of completions is always used, even if the list of completions produced is empty.) The condition is then followed by the flags as usual (as in 4.2), and possibly other condition/flag sets following a single -; the whole lot ends with a double -- before the command name. In other words, each extended completion section looks like this: -x <pattern> <flags>... [ - <pattern> <flags>... ...] -- Let's look at rcp again: this assumes you've set up $hosts as above. This uses the `n[<n>,<string>]' flag, which tells zsh to look for the <n>'th occurrence of <string> in the word, ignoring anything up to and including that. We'll use it for completing the bits of rcp's `user@host:file' combination. (Of course, the file name is on the local machine, not `host', but let's ignore that; it may still be useful.) compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \ 'n[1,@]' -k hosts -S ':' -- rcp This means: (1) try and complete a hostname (the bit before the `+'), if successful add a `:' (-S for suffix); (2) if that fails move on to try the code after the `+': look and see if there is a `:' in a word (the `n[1,:]'); if there is, complete filenames (-f) after the first of them; (3) otherwise look for an `@' and complete hostnames after the first of them (the `n[1,@]'), adding a `:' if successful; (4) if all else fails use the `-f' before the `-x' and try to complete files. So the rules for order are (1) try anything before a `+' before anything after it (2) try the conditions after a -x in order until one succeeds (3) use the default flags before the -x if none of the conditions was true. Different conditions can also be combined. There are three levels of this (in decreasing order of precedence): 1) multiple square brackets after a single condition give alternatives: for example, `s[foo][bar]' says apply the completion if the word begins with `foo' or `bar', 2) spaces between conditions mean both must match: for example, `p[1] s[-]' says this completion only applies for the first word after the command and only if it begins with a `-', 3) commas between conditions mean either can match: for example, `c[-1,-f], s[-f]' means either the previous word (-1 relative to the current one) is -f, or the current word begins with -f --- useful to use the same completion whether or not the -f has a space after it. You must be careful to put the whole expression inside quotation marks, so that it appears as a single argument to compctl. Here's a useless example just to show a general `-x' completion. compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \ 'c[-1,-j]' -P % -j -- foobar The way to read this is: for command `foobar', look and see if (((the word before the current one is -u) or (the word before the current one is -U)) and (the current word is 2)) or (the current word begins with -u); if so, try to complete user names. If the word before the current one is -j, insert the prefix `%' before the current word if it's not there already and complete job names. Otherwise, just complete file names. 4.6: And if programmable completion isn't good enough? ...then your last resort is to write a shell function to do it for you. By combining the `-U' and `-K func' flags you can get almost unlimited power. The `-U' tells zsh that whatever the completion produces is to be used, even if it doesn't fit what's there already (so that gets deleted when the completion is inserted). The `-K func' tells zsh a function name. The function is passed the part of the word already typed, and can read the rest of the line with `read -c'. It can return a set of completions via the `reply' array, and this becomes the set of possible completions. The best way to understand this is to look at `multicomp' and other functions supplied with the zsh distribution. Chapter 5: The future of zsh 5.1: What bugs are currently known and unfixed? (Plus recent important changes) Here are some of the more well-known ones, very roughly in decreasing order of significance. Many of these can also be counted against differences from ksh in question 2.1; note that this applies to the latest beta version and that simple bugs are often fixed quite quickly. There is a file Etc/BUGS in the source distribution with more detail. o `time' is ignored with builtins and can't be used with `{...}'. o `set -x' (`setopt xtrace') still has a few glitches. o Zsh's notion of the current line number (via $LINENO) is sometimes not well handled, particularly when using functions and traps. o In vi mode, `u' can go past the original modification point. o The singlelinezle option has problems with prompts containing escapes. o The `r' command does not work inside `$(...)' or ``...`' expansions. (This is fixed in 3.1.) o `typeset' handling is non-optimal, particularly with regard to flags, and is ksh-incompatible in unpredictable ways. o Nested closures in extended globbing and pattern matching, such as [[ fofo = (fo#)# ]] were not correctly handled, and there were problems with complicated exclusions using `^' or `~'. (These are fixed in version 3.1.3.) Note that a few recent changes introduce incompatibilities (these are not bugs): Changes after zsh 3.0 (3.1.x is still currently in beta): o The options ALWAYS_LAST_PROMPT (return to the line you were editing after displaying completion lists) and LIST_AMBIGUOUS (show matching files when there are several) are now set by default. This is in response to complaints that too many zsh features are never noticed by many users. To turn them off, just put `unsetopt alwayslastprompt listambiguous' in your .zshrc file. o history-search-{forward,backward} now only find previous lines where the first word is the same as the current one. For example, comp<ESC>p will find lines in the history like `comp -edit emacs', but not `compress file' any more. For this reason, `\M-n' and `\M-p' use history-beginning-search-{forward,backward} which search for a line with the same prefix up to the cursor position. It is possible to write functions which go a little closer to the original behaviour; further changes are still possible. o In vi insert mode, the cursor keys no longer work. The following will bind them: bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \ '^[[A' up-line-or-history '^[[B' down-line-or-history (unless your terminal requires `^[O' instead of `^[['). The rationale is that the insert mode and command mode keymaps for keys with prefixes are now separate. Changes since zsh 2.5: o The left hand of an assignment is no longer substituted. Thus, `$1=$2' will not work. You can use something like `eval "$1=\$2"', which should have the identical effect. o Signal traps established with the `trap' builtin are now called with the environment of the caller, as in ksh, instead of as a new function level. Traps established as functions (e.g. `TRAPINT() {...}') work as before. o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used to be the other way around. (Use of names rather than letters is generally recommended.) o `[[' is a reserved word, hence must be separated from other characters by whitespace; `{' and `}' are also reserved words if the IGNORE_BRACES option is set. o The option CSH_JUNKIE_PAREN has been removed: csh-like code now always does what it looks like it does, so `if ( ... ) ...' executes the code in parentheses in a subshell. To make this useful, the syntax expected after an `if', etc., is less strict than in other shells. o `foo=*' does not perform globbing immediately on the right hand side of the assignment; the old behaviour now requires the option GLOB_ASSIGN. (`foo=(*)' is and has always been the consistent way of doing this.) o <> performs redirection of input and output to the specified file. For numeric globs, you now need <->. o The command line qualifiers exec, noglob, command, - are now treated more like builtin commands: previously they were syntactically special. This should make it easier to perform tricks with them (disabling, hiding in parameters, etc.). o The pushd builtin has been rewritten for compatibility with other shells. The old behavour can be achieved with a shell function. o The current version now uses ~'s for directory stack substitution instead of ='s. This is for consistency: all other directory substitution (~user, ~name, ~+, ...) used a tilde, while =<number> caused problems with =program substitution. o The `HISTLIT' option was broken in various ways and has been removed: the rewritten history mechanism doesn't alter history lines, making the option unnecessary. o History expansion is disabled in single-quoted strings, like other forms of expansion -- hence exclamation marks there should not be backslashed. o The `$HISTCHARS' variable is now `$histchars'. Currently both are tied together for compatibility. o The PROMPT_SUBST option now performs backquote expansion -- hence you should quote these in prompts. (SPROMPT has changed as a result.) o Quoting in prompts has changed: close parentheses inside ternary expressions should be quoted with a %; history is now %!, not !. Backslashes are no longer special. 5.2: Where do I report bugs, get more info / who's working on zsh? The shell is being maintained by various (entirely self-appointed) subscribers to the mailing list, zsh-workers@math.gatech.edu so mail on any issues (bug reports, suggestions, complaints...) related to the development of the shell should be sent there. If you want someone to mail you directly, say so. Most patches to zsh appear there first. Please note when reporting bugs that many exist only on certain architectures, which the developers may not have access to. In this case debugging information, as detailed as possible, is particularly welcome. Two progressively lower volume lists exist, one with messages concerning the use of zsh, zsh-users@math.gatech.edu and one just containing announcements: about releases, about major changes in the shell, or this FAQ, for example, zsh-announce@math.gatech.edu (posting to the last one is currently restricted). Note that you should only join one of these lists: people on zsh-workers receive all the lists, and people on zsh-users will also receive the announcements list. The lists are handled by an automated server. The instructions for zsh-announce and zsh-users are the same as for zsh-workers: just change zsh-workers to whatever in the following. To join zsh-workers, send email to zsh-workers-request@math.gatech.edu with the *subject* line (this is a change from the old list) subscribe <your-email-address> e.g. Subject: subscribe P.Stephenson@swansea.ac.uk and you can unsubscribe in the same way. The list maintainer, Richard Coleman, can be reached at coleman@math.gatech.edu. The list from May 1992 to May 1995 is archived in ftp://ftp.sterling.com/zsh/zsh-list/YY-MM where YY-MM are the year and month in digits. More recent mailings up to date are to be found at http://www.zsh.org/mla/ at the main zsh archive in Australia. Of course, you can also post zsh queries to the Usenet group comp.unix.shell; if all else fails, you could even e-mail me. 5.3: What's on the wish-list? With version 3, the code is much cleaner than before, but still bears the marks of the ages and many things could be done much better with a rewrite. A more efficient set of code for lexing/parsing/execution might also be an advantage. Volunteers are particularly welcome for these tasks. An improved line editor, with user-definable functions and binding of multiple functions to keystrokes, is being developed. o Loadable module support (will be in 3.1 but much work still needs doing). o Ksh compatibility could be improved. o Option for glob qualifiers to follow perl syntax (a traditional item). o Binding of shell functions to key strokes, accessing editing buffer from functions, executing zle functions as a command: now under development for 3.1. o Users should be able to create their own foopath/FOOPATH array/path combinations. 5.4: Will zsh have problems in the year 2000? (This information was written by Bart Schaefer. Note it is a description of the state of affairs as seen by the developers, it is not a guarantee!) You can confirm the following by looking at the source code yourself if necessary; there's no other definitive reference: Zsh uses UNIX/POSIX time_t, timeval, and tm data types for internal date manipulations. These types either do not store year values at all (for example, time_t is measured in seconds since midnight, Jan 1, 1970) or store them as integer types and NOT as pairs of digits. Thus there can be no overflows at year 2000. On some unix systems, time_t is a 32-bit value and will overflow during the year 2038, but more modern systems use a 64-bit time_t. The only input and output of dates that zsh performs for its own use is optional history time-stamping. This is performed using time_t values converted to long integers, which are either 32 or 64 bits, see above. Note, however, that zsh does provide facilities for formatted date output, in particular in prompt escapes such as `%W' and `%D' using `print -P', so it's possible that scripts written for zsh might employ 2-digit years. Shell scripts should always be considered separate programs and therefore evaluated individually. Acknowledgments: Thanks to zsh-list, in particular Bart Schaefer, for suggestions regarding this document. Zsh has been in the hands of archivists Jim Mattson, Bas de Bakker, Richard Coleman, Zoltan Hidvegi and Andrew Main, and the mailing list has been run by Peter Gray, Rick Ohnemus and Richard Coleman, all of whom deserve thanks. The world is eternally in the debt of Paul Falstad for inventing zsh in the first place (though the wizzo extended completion is by Sven Wischnowsky). Copyright Information: This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997, 1998. This text originates in the U.K. and the author asserts his moral rights under the Copyrights, Designs and Patents Act, 1988. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, modify, and distribute this documentation for any purpose, provided that the above copyright notice appears in all copies of this documentation. Remember, however, that this document changes monthly and it may be more useful to provide a pointer to it rather than the entire text. A suitable pointer is "information on the Z-shell can be obtained on the World Wide Web at URL http://sunsite.auc.dk/zsh/".