Re: shopt can't set extglob in a sub-shell?

[John Kearney]

On 02/25/2012 09:42 PM, Davide Baldini wrote:
> Configuration Information [Automatically generated, do not
> change]: Machine: i486 OS: linux-gnu Compiler: gcc Compilation
> CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='i486'
> -DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i486-pc-linux-gnu'
> -DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash'
> -DSHELL -DHAVE_CONFIG_H   -I.  -I../bash -I../bash/include
> -I../bash/lib   -g -O2 -Wall uname output: Linux debianBunker
> 2.6.26-2-686 #1 SMP Wed Sep 21 04:35:47 UTC 2011 i686 GNU/Linux 
> Machine Type: i486-pc-linux-gnu
> 
> Bash Version: 4.1 Patch Level: 5 Release Status: release


Ok so had a play around with it. Its not specific to sub shells its
commands.

so the following also doesn't work.

shopt -u extglob
if true; then
  shopt -s extglob
  echo !(x)
fi

this is because bash treats the entire if statement as a command. so
the second shopt isn't evaluate before the !(x) is parsed. therefore
the error message. The error message is a parsing error not an
expansion error I think.

so bash sees the above as
shopt -u extglob
if true; then   shopt -s extglob;   echo !(x); fi

as a workaround you could try/use is this it delays parsing the !(x)
until after the shopt is evaluated.

(
        shopt -s extglob
        eval 'echo !(x)'
)


Not sure if this is expected behavior.
hth
deth.