* question about glob qualifier format (#qx) @ 2013-09-20 11:11 Han Pingtian 2013-09-20 11:38 ` Peter Stephenson 0 siblings, 1 reply; 4+ messages in thread From: Han Pingtian @ 2013-09-20 11:11 UTC (permalink / raw) To: zsh-users Hello, I'm confused about the usage of glob qualifier format "(#qx)". The man page says: ...... Also, as the syntax is unambiguous, the expression will be treated as glob qualifiers just as long any parentheses contained within it are balanced; appearance of `|', `(' or `~' does not negate the effect. But looks like if I put them in parentheses, it will not take effect any more: $ ls 1.c 2.h a b slink $ echo *((#q/)) 1.c 2.h a b slink So I'd like to know how to comprehend the manpage here? Thanks in advance! ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: question about glob qualifier format (#qx) 2013-09-20 11:11 question about glob qualifier format (#qx) Han Pingtian @ 2013-09-20 11:38 ` Peter Stephenson 2013-09-20 23:39 ` Han Pingtian 0 siblings, 1 reply; 4+ messages in thread From: Peter Stephenson @ 2013-09-20 11:38 UTC (permalink / raw) To: zsh-users On Fri, 20 Sep 2013 19:11:10 +0800 Han Pingtian <hanpt@linux.vnet.ibm.com> wrote: > I'm confused about the usage of glob qualifier format "(#qx)". The man > page says: > > ...... Also, as the syntax is unambiguous, > the expression will be treated as glob qualifiers just as long any > parentheses contained within it are balanced; appearance of `|', `(' or > `~' does not negate the effect. > > But looks like if I put them in parentheses, it will not take effect any more: > > > $ ls > 1.c 2.h a b slink > $ echo *((#q/)) > 1.c 2.h a b slink > > So I'd like to know how to comprehend the manpage here? Thanks in > advance! Because of the ambiguity between glob qualifiers without the #q and parenthesised groups, the shell guesses which is which. An expression containing "|" makes it guess that it's a parenthesised group rather than a set of glob qualifiers. However, if the *first* open parenthesis (there's no reason to double them) is followed by #q (and EXTENDED_GLOB is set), it knows for sure that this is a glob qualifier, so it doesn't need to do any guessing. This is there as an additional help; you don't need to change your normal use of glob qualifiers just because you've signalled them explicitly with #q. (#q/) works fine. pws ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: question about glob qualifier format (#qx) 2013-09-20 11:38 ` Peter Stephenson @ 2013-09-20 23:39 ` Han Pingtian 2013-09-21 8:30 ` Bart Schaefer 0 siblings, 1 reply; 4+ messages in thread From: Han Pingtian @ 2013-09-20 23:39 UTC (permalink / raw) To: zsh-users On Fri, Sep 20, 2013 at 12:38:30PM +0100, Peter Stephenson wrote: > On Fri, 20 Sep 2013 19:11:10 +0800 > Han Pingtian <hanpt@linux.vnet.ibm.com> wrote: > > I'm confused about the usage of glob qualifier format "(#qx)". The man > > page says: > > > > ...... Also, as the syntax is unambiguous, > > the expression will be treated as glob qualifiers just as long any > > parentheses contained within it are balanced; appearance of `|', `(' or > > `~' does not negate the effect. > > > > But looks like if I put them in parentheses, it will not take effect any more: > > > > > > $ ls > > 1.c 2.h a b slink > > $ echo *((#q/)) > > 1.c 2.h a b slink > > > > So I'd like to know how to comprehend the manpage here? Thanks in > > advance! > > Because of the ambiguity between glob qualifiers without the #q and > parenthesised groups, the shell guesses which is which. An expression > containing "|" makes it guess that it's a parenthesised group rather > than a set of glob qualifiers. However, if the *first* open parenthesis > (there's no reason to double them) is followed by #q (and EXTENDED_GLOB > is set), it knows for sure that this is a glob qualifier, so it doesn't > need to do any guessing. > > This is there as an additional help; you don't need to change your > normal use of glob qualifiers just because you've signalled them > explicitly with #q. (#q/) works fine. > > pws But I'm still confusing on the manpage :) If I want to list all symbolic links and directories in current directory, this expression doesn't work: $ echo (*(#q@)|*(#q/)) we must write it as : $ echo *(#q@) *(#q/) I cannot see any difference between '(#qx)' format and 'bare glob qualifier' format on being disabled by '|', '('. Please advise. Thanks. ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: question about glob qualifier format (#qx) 2013-09-20 23:39 ` Han Pingtian @ 2013-09-21 8:30 ` Bart Schaefer 0 siblings, 0 replies; 4+ messages in thread From: Bart Schaefer @ 2013-09-21 8:30 UTC (permalink / raw) To: zsh-users On Sep 21, 7:39am, Han Pingtian wrote: } } But I'm still confusing on the manpage :) } } If I want to list all symbolic links and directories in current } directory, this expression doesn't work: } } $ echo (*(#q@)|*(#q/)) A few lines above the excerpt you previously quoted from the manual, it says: If the option EXTENDED_GLOB is set, a different syntax for glob qualifiers is available, namely `(#qx)' where x is any of the same glob qualifiers used in the other format. The qualifiers must still appear at the end of the pattern. } I cannot see any difference between '(#qx)' format and 'bare glob } qualifier' format on being disabled by '|', '('. Please advise. The difference is with e.g. (.). With BARE_GLOB_QUAL, *(.) matches all plain files. With NO_BARE_GLOB_QUAL, *(.) matches files whose name ends in a dot, and *(#q.) is needed to match all plain files. } we must write it as : } } $ echo *(#q@) *(#q/) More than one of these lists can be combined, separated by commas. The whole list matches if at least one of the sublists matches (they are `or'ed, the qualifiers in the sublists are `and'ed). So: % echo *(#q@,/) *should* do what you want, but see below about potential bugs .... I accidentally encountered some odd behavior while confirming this. With NO_EXTENDED_GLOB, #q is not supposed to be available to introduce qualifiers. However % setopt NO_EXTENDED_GLOB % echo *(#q@) <list of symlinks> Whereas % echo *(#q/) zsh: unknown file attribute This is inconsistent, that is, sometimes (#q@) will also give "unknown" and (#q/) will work. The more I play with it the less consistently it behaves. *(#q@,/) may produce any of zsh: unknown file attribute zsh: bad pattern: *(#q@,/) or the intended list of files, depending on ... well, I can't tell what it depends on, possibly previous globs or what the current directory is, or how often EXTENDED_GLOB or BARE_GLOB_QUAL have been toggled on and off. In fact once I even got: % setopt CSH_NULL_GLOB % print -l *(#q@) *(#q/) zsh: bad pattern: *(#q/) (even when */ matches several directories, and *(/) matches them with BARE_GLOB_QUAL). So something about the parsing for #q may be wonky. All of this works very nicely when BARE_GLOB_QUAL is enabled, which it is by default, which is probably why nobody noticed before that #q is doing strange things. ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2013-09-21 8:30 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2013-09-20 11:11 question about glob qualifier format (#qx) Han Pingtian 2013-09-20 11:38 ` Peter Stephenson 2013-09-20 23:39 ` Han Pingtian 2013-09-21 8:30 ` Bart Schaefer
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