* Prefixed backslash removed when completing command @ 2010-05-20 11:28 Mikael Auno 2010-05-20 12:39 ` Peter Stephenson 2010-10-27 9:06 ` Mikael Auno 0 siblings, 2 replies; 11+ messages in thread From: Mikael Auno @ 2010-05-20 11:28 UTC (permalink / raw) To: zsh-workers [-- Attachment #1: Type: text/plain, Size: 577 bytes --] Hi. I don't know if prefixing a command with a backslash to suppress alias expansion is a intentional feature or not. If it is though, tab completing a (complete or incomplete) command prefixed with a backslash ought not remove the backslash. Current behavior seems to be to complete something like "\mpla" to "mplayer" and not to "\mplayer" as I would expect. I would be happy to try to fix it myself if no one has time to do it. A pointer on where to start looking in that case would be good though as I'm not at all familiar with the code of Zsh. Mikael Auno [-- Attachment #2: OpenPGP digital signature --] [-- Type: application/pgp-signature, Size: 835 bytes --] ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: Prefixed backslash removed when completing command 2010-05-20 11:28 Prefixed backslash removed when completing command Mikael Auno @ 2010-05-20 12:39 ` Peter Stephenson 2010-10-27 9:06 ` Mikael Auno 1 sibling, 0 replies; 11+ messages in thread From: Peter Stephenson @ 2010-05-20 12:39 UTC (permalink / raw) To: zsh-workers On Thu, 20 May 2010 13:28:51 +0200 Mikael Auno <auno@kth.se> wrote: > Hi. I don't know if prefixing a command with a backslash to suppress > alias expansion is a intentional feature or not. If it is though, tab > completing a (complete or incomplete) command prefixed with a > backslash ought not remove the backslash. Current behavior seems to > be to complete something like "\mpla" to "mplayer" and not to > "\mplayer" as I would expect. > > I would be happy to try to fix it myself if no one has time to do it. > A pointer on where to start looking in that case would be good though > as I'm not at all familiar with the code of Zsh. You're quite right that this should work better, but I suspect fixing it is a real pig. Quoting is one of the messiest parts of completion (regular viewers will know this is rather a strong statement). I think fixing it properly by leaving all quoting in place isn't going to be easy (to put it mildly). I think you have a workaround, though: use an initial single quote. Not only does that get kept, the closing single quote is put in place afterwards. Is this good enough? (It would be good to document this but goodness knows where it goes.) -- Peter Stephenson <pws@csr.com> Software Engineer Tel: +44 (0)1223 692070 Cambridge Silicon Radio Limited Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, UK Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: Prefixed backslash removed when completing command 2010-05-20 11:28 Prefixed backslash removed when completing command Mikael Auno 2010-05-20 12:39 ` Peter Stephenson @ 2010-10-27 9:06 ` Mikael Auno 2010-10-27 10:02 ` Peter Stephenson 1 sibling, 1 reply; 11+ messages in thread From: Mikael Auno @ 2010-10-27 9:06 UTC (permalink / raw) To: zsh-workers Peter Stephenson wrote: > Mikael Auno wrote: >> Hi. I don't know if prefixing a command with a backslash to suppress >> alias expansion is a intentional feature or not. If it is though, tab >> completing a (complete or incomplete) command prefixed with a >> backslash ought not remove the backslash. Current behavior seems to >> be to complete something like "\mpla" to "mplayer" and not to >> "\mplayer" as I would expect. >> >> I would be happy to try to fix it myself if no one has time to do it. >> A pointer on where to start looking in that case would be good though >> as I'm not at all familiar with the code of Zsh. > > You're quite right that this should work better, but I suspect fixing it is > a real pig. Quoting is one of the messiest parts of completion (regular > viewers will know this is rather a strong statement). I think fixing it > properly by leaving all quoting in place isn't going to be easy (to put it > mildly). > > I think you have a workaround, though: use an initial single quote. Not > only does that get kept, the closing single quote is put in place > afterwards. Is this good enough? (It would be good to document this but > goodness knows where it goes.) (I did not see this reply until now as I am not on the list and as such did not receive the reply directly. I only saw it now as I happened to find the online archive of the mailing list.) If I am not completely misunderstanding your reply, I think you misunderstood my issue. My issue has nothing to do with either single or double quotes (they are only there in the original message to separate the examples from the rest of the text), but with the backslash. When I try to tab complete something starting with a leading backslash, e.g. \mpla, then it is completed to mplayer (without a leading backslash) instead of \mplayer (with a leading backslash) as I would expect. I hope this clarifies the issue. Mikael Auno ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: Prefixed backslash removed when completing command 2010-10-27 9:06 ` Mikael Auno @ 2010-10-27 10:02 ` Peter Stephenson 2010-10-27 10:41 ` Mikael Auno 2010-10-27 15:43 ` Bart Schaefer 0 siblings, 2 replies; 11+ messages in thread From: Peter Stephenson @ 2010-10-27 10:02 UTC (permalink / raw) To: Mikael Auno, zsh-workers On Wed, 27 Oct 2010 11:06:16 +0200 Mikael Auno <auno@kth.se> wrote: > If I am not completely misunderstanding your reply, I think you > misunderstood my issue. My issue has nothing to do with either single > or double quotes (they are only there in the original message to > separate the examples from the rest of the text), but with the > backslash. No, you've misunderstood my reply. > When I try to tab complete something starting with a leading > backslash, e.g. \mpla, then it is completed to mplayer (without a > leading backslash) instead of \mplayer (with a leading backslash) as > I would expect. Yes, I realise that. Here's my reply rephrased. The internals of completion are complicated. There is no prospect of it ever being able to preserve quotations in a general way. In particular there is no prospect of it ever being able to retain backslashes that have no basic syntactic effect. Slight digression on what I mean by a "basic syntactic effect". Aliases are a special case as they are expanded on input, so things that are usually ignored in the usual shell grammar become significant; completion doesn't know anything about this. Completion just tries to muddle through and produce an expression that (ignoring the alias problem) is quoted in an appropriate way for the shell to process the word on the command line. If quoting is done using backslashes the only backslashes left will be those needed for special characters. Completion makes no attempt to try to remember how the original word looked and reconstruct it. However, if quoting is done with a single or double quote character at the start of the word, that form of quoting is preserved even if it's not (apparently) needed to quote special characters. In this case, completion remembers the whole word is quoted. This is much simpler than trying to remember what happens character by character. So if you really insist on having a backslash, you are stuck, as far as completion is concerned. (You still have the possibility of writing line editor, non-completion, functions to quote the word how you want.) However, *if* it happens to be the case that you are simply trying to ensure the word is quoted, somehow, you can get away with starting it with a single quote, and forget about the backslash. The single quote is preserved during completion, unlike the backslash, and a closing quote appended. So it all works, and you have completed a quoted word. I'm not aware of anywhere in the shell that requires you to quote a word as \mplayer rather than 'mplayer'. They should have the same effect in every case except the bizarre one where you have defined 'mplayer', including the quotes, as an alias. So if you started with a single quote (I know that's not what you asked about) it should do the right thing, or I'd like to hear why it doesn't. -- Peter Stephenson <pws@csr.com> Software Engineer Tel: +44 (0)1223 692070 Cambridge Silicon Radio Limited Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, UK Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: Prefixed backslash removed when completing command 2010-10-27 10:02 ` Peter Stephenson @ 2010-10-27 10:41 ` Mikael Auno 2010-10-27 10:48 ` Peter Stephenson 2010-10-27 10:49 ` Prefixed backslash removed when completing command Mikael Magnusson 2010-10-27 15:43 ` Bart Schaefer 1 sibling, 2 replies; 11+ messages in thread From: Mikael Auno @ 2010-10-27 10:41 UTC (permalink / raw) To: Peter Stephenson; +Cc: zsh-workers On 2010-10-27 12:02, Peter Stephenson wrote: > On Wed, 27 Oct 2010 11:06:16 +0200 > Mikael Auno<auno@kth.se> wrote: >> If I am not completely misunderstanding your reply, I think you >> misunderstood my issue. My issue has nothing to do with either single >> or double quotes (they are only there in the original message to >> separate the examples from the rest of the text), but with the >> backslash. > > No, you've misunderstood my reply. > >> When I try to tab complete something starting with a leading >> backslash, e.g. \mpla, then it is completed to mplayer (without a >> leading backslash) instead of \mplayer (with a leading backslash) as >> I would expect. > > Yes, I realise that. Here's my reply rephrased. > > The internals of completion are complicated. There is no prospect of it > ever being able to preserve quotations in a general way. In particular > there is no prospect of it ever being able to retain backslashes that > have no basic syntactic effect. > > Slight digression on what I mean by a "basic syntactic effect". Aliases > are a special case as they are expanded on input, so things that are > usually ignored in the usual shell grammar become significant; > completion doesn't know anything about this. Completion just tries to > muddle through and produce an expression that (ignoring the alias > problem) is quoted in an appropriate way for the shell to process the > word on the command line. > > If quoting is done using backslashes the only backslashes left will be > those needed for special characters. Completion makes no attempt to try > to remember how the original word looked and reconstruct it. > > However, if quoting is done with a single or double quote character at > the start of the word, that form of quoting is preserved even if it's > not (apparently) needed to quote special characters. In this case, > completion remembers the whole word is quoted. This is much simpler > than trying to remember what happens character by character. > > So if you really insist on having a backslash, you are stuck, as far as > completion is concerned. (You still have the possibility of writing > line editor, non-completion, functions to quote the word how you want.) > > However, *if* it happens to be the case that you are simply trying to > ensure the word is quoted, somehow, you can get away with starting it > with a single quote, and forget about the backslash. The single quote > is preserved during completion, unlike the backslash, and a closing > quote appended. So it all works, and you have completed a quoted word. > > I'm not aware of anywhere in the shell that requires you to quote a word > as \mplayer rather than 'mplayer'. They should have the same effect in > every case except the bizarre one where you have defined 'mplayer', > including the quotes, as an alias. So if you started with a single > quote (I know that's not what you asked about) it should do the right > thing, or I'd like to hear why it doesn't. You are completely correct. I misunderstood your reply as I did not know that the backslash was at all related to quoting or that ordinary quoting had the same result as prefixing a command with a backslash with respect to suppressing alias expansion. Prefixing with single or double quotes works great, especially as the closing quote is appended automatically. Thank you for this insight, Mikael Auno ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: Prefixed backslash removed when completing command 2010-10-27 10:41 ` Mikael Auno @ 2010-10-27 10:48 ` Peter Stephenson 2010-10-27 12:23 ` Štěpán Němec 2010-10-27 10:49 ` Prefixed backslash removed when completing command Mikael Magnusson 1 sibling, 1 reply; 11+ messages in thread From: Peter Stephenson @ 2010-10-27 10:48 UTC (permalink / raw) To: Mikael Auno, zsh-workers On Wed, 27 Oct 2010 12:41:05 +0200 Mikael Auno <auno@kth.se> wrote: > You are completely correct. I misunderstood your reply as I did not > know that the backslash was at all related to quoting or that > ordinary quoting had the same result as prefixing a command with a > backslash with respect to suppressing alias expansion. The manual currently just gives the one example which, given your experience, is probably not very helpful. Index: Doc/Zsh/grammar.yo =================================================================== RCS file: /cvsroot/zsh/zsh/Doc/Zsh/grammar.yo,v retrieving revision 1.18 diff -p -u -r1.18 grammar.yo --- Doc/Zsh/grammar.yo 3 Feb 2010 18:36:57 -0000 1.18 +++ Doc/Zsh/grammar.yo 27 Oct 2010 10:47:09 -0000 @@ -477,12 +477,15 @@ cindex(aliases, global) An alias is defined using the tt(alias) builtin; global aliases may be defined using the tt(-g) option to that builtin. -Alias expansion is done on the shell input before any -other expansion except history expansion. Therefore, -if an alias is defined for the word tt(foo), alias expansion -may be avoided by quoting part of the word, e.g. tt(\foo). -But there is nothing to prevent an alias being defined -for tt(\foo) as well. +Alias expansion is done on the shell input before any other expansion +except history expansion. Therefore, if an alias is defined for the +word tt(foo), alias expansion may be avoided by quoting part of the +word, e.g. tt(\foo). But there is nothing to prevent an alias being +defined for tt(\foo) as well. For use with completion, which would +remove an initial backslash following by a character that isn't special, +it may be more convenient to quote the word by starting with a single +quote, i.e. tt('foo); completion will automatically add the trailing +single quote. There is a commonly encountered problem with aliases illustrated by the following code: -- Peter Stephenson <pws@csr.com> Software Engineer Tel: +44 (0)1223 692070 Cambridge Silicon Radio Limited Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, UK Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: Prefixed backslash removed when completing command 2010-10-27 10:48 ` Peter Stephenson @ 2010-10-27 12:23 ` Štěpán Němec 2010-10-27 12:29 ` Mikael Magnusson 2010-10-27 12:49 ` PATCH: document more alias problems Peter Stephenson 0 siblings, 2 replies; 11+ messages in thread From: Štěpán Němec @ 2010-10-27 12:23 UTC (permalink / raw) To: Peter Stephenson; +Cc: Mikael Auno, zsh-workers Peter Stephenson <Peter.Stephenson@csr.com> writes: [...] > +remove an initial backslash following by a character that isn't special, ^^^^^^^^^ followed Thanks for that addition, I tended to think the same as Mikael (Auno) before (i.e. routinely use backslash to prevent alias expansion, not realising quotes work just as well). Štěpán ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: Prefixed backslash removed when completing command 2010-10-27 12:23 ` Štěpán Němec @ 2010-10-27 12:29 ` Mikael Magnusson 2010-10-27 12:49 ` PATCH: document more alias problems Peter Stephenson 1 sibling, 0 replies; 11+ messages in thread From: Mikael Magnusson @ 2010-10-27 12:29 UTC (permalink / raw) To: Mikael Auno, zsh-workers On 27 October 2010 14:23, Štěpán Němec <stepnem@gmail.com> wrote: > Peter Stephenson <Peter.Stephenson@csr.com> writes: > > [...] >> +remove an initial backslash following by a character that isn't special, > ^^^^^^^^^ > followed > > Thanks for that addition, I tended to think the same as Mikael (Auno) > before (i.e. routinely use backslash to prevent alias expansion, not > realising quotes work just as well). Another thing that will incidentally prevent alias expansion and still run the command is prefixing the command with a = (this will expand the word to the full path to the binary, anywhere on the command line). -- Mikael Magnusson ^ permalink raw reply [flat|nested] 11+ messages in thread
* PATCH: document more alias problems 2010-10-27 12:23 ` Štěpán Němec 2010-10-27 12:29 ` Mikael Magnusson @ 2010-10-27 12:49 ` Peter Stephenson 1 sibling, 0 replies; 11+ messages in thread From: Peter Stephenson @ 2010-10-27 12:49 UTC (permalink / raw) To: zsh-workers While I'm at it, it's probably high time that another note on alias problems was promoted to the manual. It's been in the FAQ for a while but it could do with highlighting since it's really annoying and confusing if you come across it. Index: Doc/Zsh/grammar.yo =================================================================== RCS file: /cvsroot/zsh/zsh/Doc/Zsh/grammar.yo,v retrieving revision 1.20 diff -p -u -r1.20 grammar.yo --- Doc/Zsh/grammar.yo 27 Oct 2010 12:29:13 -0000 1.20 +++ Doc/Zsh/grammar.yo 27 Oct 2010 12:45:19 -0000 @@ -500,6 +500,27 @@ is too late to expand the newly defined a problem in shell scripts, functions, and code executed with `tt(source)' or `tt(.)'. Consequently, use of functions rather than aliases is recommended in non-interactive code. + +Note also the unhelpful interaction of aliases and function definitions: + +example(alias func='noglob func' +func+LPAR()RPAR() { + echo Do something with $* +}) + +Because aliases are expanded in function definitions, this causes the +following command to be executed: + +example(noglob func+LPAR()RPAR() { + echo Do something with $* +}) + +which defines tt(noglob) as well as tt(func) as functions with the +body given. To avoid this, either quote the name tt(func) or use the +alternative function definition form `tt(function func)'. Ensuring the +alias is defined after the function works but is problematic if the +code fragment might be re-executed. + texinode(Quoting)()(Aliasing)(Shell Grammar) sect(Quoting) cindex(quoting) -- Peter Stephenson <pws@csr.com> Software Engineer Tel: +44 (0)1223 692070 Cambridge Silicon Radio Limited Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, UK Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: Prefixed backslash removed when completing command 2010-10-27 10:41 ` Mikael Auno 2010-10-27 10:48 ` Peter Stephenson @ 2010-10-27 10:49 ` Mikael Magnusson 1 sibling, 0 replies; 11+ messages in thread From: Mikael Magnusson @ 2010-10-27 10:49 UTC (permalink / raw) To: Mikael Auno, zsh-workers On 27 October 2010 12:41, Mikael Auno <auno@kth.se> wrote: > You are completely correct. I misunderstood your reply as I did not know > that the backslash was at all related to quoting or that ordinary quoting > had the same result as prefixing a command with a backslash with respect to > suppressing alias expansion. Prefixing with single or double quotes works > great, especially as the closing quote is appended automatically. > > Thank you for this insight, It's a little bit different from that even. Alias expansion is done literally on the input basically just split on spaces. So even things like ''mplayer or mplaye\r or mplayer"" will "cancel" out alias expansion. That the quotes disappear in normal shell parsing is sort of a lucky coincidence as far as the alias expansion is concerned. :) -- Mikael Magnusson ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: Prefixed backslash removed when completing command 2010-10-27 10:02 ` Peter Stephenson 2010-10-27 10:41 ` Mikael Auno @ 2010-10-27 15:43 ` Bart Schaefer 1 sibling, 0 replies; 11+ messages in thread From: Bart Schaefer @ 2010-10-27 15:43 UTC (permalink / raw) To: Mikael Auno, zsh-workers On Oct 27, 11:02am, Peter Stephenson wrote: } } The internals of completion are complicated. There is no prospect of it } ever being able to preserve quotations in a general way. In particular } there is no prospect of it ever being able to retain backslashes that } have no basic syntactic effect. It strikes me that it might be possible to special-case a backslash as the very first character in $BUFFER, but it's probably not worth the effort ... ^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2010-10-27 15:44 UTC | newest] Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2010-05-20 11:28 Prefixed backslash removed when completing command Mikael Auno 2010-05-20 12:39 ` Peter Stephenson 2010-10-27 9:06 ` Mikael Auno 2010-10-27 10:02 ` Peter Stephenson 2010-10-27 10:41 ` Mikael Auno 2010-10-27 10:48 ` Peter Stephenson 2010-10-27 12:23 ` Štěpán Němec 2010-10-27 12:29 ` Mikael Magnusson 2010-10-27 12:49 ` PATCH: document more alias problems Peter Stephenson 2010-10-27 10:49 ` Prefixed backslash removed when completing command Mikael Magnusson 2010-10-27 15:43 ` Bart Schaefer
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