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From: Martin Schulte <gnu@schrader-schulte.de>
Newsgroups: gnu.bash.bug
Subject: Re: Backslash missing in brace expansion
Date: Fri, 6 Dec 2019 05:53:04 +0100
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Hi Chet, hi all!

On Thu, 5 Dec 2019 12:01:31 -0800
Chet Ramey <chet.ramey@case.edu> wrote:

> On 12/5/19 11:11 AM, Martin Schulte wrote:
> > Hello,
> > 
> > please have a look:
> > 
> > $ uname -a
> > Linux martnix4 4.9.0-11-amd64 #1 SMP Debian 4.9.189-3+deb9u2
> > (2019-11-11) x86_64 GNU/Linux $ echo ${BASH_VERSINFO[@]}
> > 4 4 12 1 release x86_64-pc-linux-gnu
> > $ set -x
> > $ echo {Z..a}
> > + echo Z '[' '' ']' '^' _ '`' a
> > Z [  ] ^ _ ` a
> > 
> > It looks as if the backslash (between [ and ] in ASCII code) is
> > missing in brace expansion. The same behaviour seems to be found in
> > bash 5.0.
> 
> It's an unquoted backslash, which is removed by quote removal when the
> words are expanded. Look at the extra space between `[' and `]'; that's
> the null argument resulting from the unquoted backslash.

Yes - sure. But then I'm wondering why the unquoted backtick doesn't
start command substitution:

$ echo {Z..a}
Z [  ] ^ _ ` a
$ echo Z [ \ ] ^ _ ` a
> 

Best regards,

Martin