Re: question about glob qualifier format (#qx)

[Peter Stephenson <p.stephenson@samsung.com>]

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