Re: Backslash missing in brace expansion

[Eric Blake]

On 12/5/19 10:53 PM, Martin Schulte wrote:

> > > (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:

It may be version dependent:

$ echo ${BASH_VERSINFO[@]}
5 0 7 1 release x86_64-redhat-linux-gnu

$ echo b{Z..a}d
bash: bad substitution: no closing "`" in `d

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
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