strange expansion of <(cat p.main.{optional,extra})
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
uname output: Linux beothuk.imag.fr 2.6.18-4-686 #1 SMP Mon Mar 26 17:17:36 UTC
2007 i686 GNU/Linux
Machine Type: i486-pc-linux-gnu
Bash Version: 3.1
Patch Level: 17
Release Status: release
Description:
Hi,
The expansion of echo <(cat /etc/{passwd,motd}) is rather surprising:
$ echo <(cat p.main.{optional,extra})
++ cat p.main.optional
cat: p.main.optional: No such file or directory
++ cat p.main.extra
cat: p.main.extra: No such file or directory
+ echo /dev/fd/63 /dev/fd/62
/dev/fd/63 /dev/fd/62
I would have expected to be expanded to <(cat /etc/passwd /etc/motd) first.
Repeat-By:
echo <(cat /etc/passwd /etc/motd)
tested with bash 3.1 and 3.2. Someone else told me on IRC that 2.05 was also
affected.
Lucas.
___
Bug-bash mailing list
Bug-bash@gnu.org
http://lists.gnu.org/mailman/listinfo/bug-bash
Re: strange expansion of <(cat p.main.{optional,extra})
On 18/04/07 at 11:11 +0200, Andreas Schwab wrote:
> Chet Ramey <[EMAIL PROTECTED]> writes:
>
> > [EMAIL PROTECTED] wrote:
> >
> >> Bash Version: 3.1
> >> Patch Level: 17
> >> Release Status: release
> >>
> >> Description:
> >> Hi,
> >>
> >> The expansion of echo <(cat /etc/{passwd,motd}) is rather surprising:
> >> $ echo <(cat p.main.{optional,extra})
> >> ++ cat p.main.optional
> >> cat: p.main.optional: No such file or directory
> >> ++ cat p.main.extra
> >> cat: p.main.extra: No such file or directory
> >> + echo /dev/fd/63 /dev/fd/62
> >> /dev/fd/63 /dev/fd/62
> >>
> >> I would have expected to be expanded to <(cat /etc/passwd /etc/motd) first.
> >
> > That's not how it works. Brace expansion is the first expansion performed.
> > The manual page says:
> >
> > "Brace expansion is performed before any other expansions, and any char-
> > acters special to other expansions are preserved in the result. It is
> > strictly textual. Bash does not apply any syntactic interpretation to
> > the context of the expansion or the text between the braces."
>
> If it would be done strictly textual, the resulting expansion would
> actually be this:
>
> $ echo <(cat p.main.optional) p.main.extra)
>
> which would be a syntax error.
Well, no, because bash expands *parameters*, not words. So the prefix is
"<(cat /etc/", and the suffix is ")".
--
| Lucas Nussbaum
| [EMAIL PROTECTED] http://www.lucas-nussbaum.net/ |
| jabber: [EMAIL PROTECTED] GPG: 1024D/023B3F4F |
___
Bug-bash mailing list
Bug-bash@gnu.org
http://lists.gnu.org/mailman/listinfo/bug-bash
Re: strange expansion of <(cat p.main.{optional,extra})
On 18/04/07 at 14:37 +0200, Andreas Schwab wrote: > Eric Blake <[EMAIL PROTECTED]> writes: > > > According to Andreas Schwab on 4/18/2007 4:01 AM: > >> Lucas Nussbaum <[EMAIL PROTECTED]> writes: > >> > >>> Well, no, because bash expands *parameters*, not words. So the prefix is > >>> "<(cat /etc/", and the suffix is ")". > >> > >> But that would not be a *strict textual* expansion. > > > > According to 'man bash', brace expansion is documented as being able to > > expand one word into many. > > The documentation talks about strings, not words. Based on the behaviour, I think that bash first splits the command line into a list of parameters, then expands each parameter. <(...) is a single parameter. -- | Lucas Nussbaum | [EMAIL PROTECTED] http://www.lucas-nussbaum.net/ | | jabber: [EMAIL PROTECTED] GPG: 1024D/023B3F4F | ___ Bug-bash mailing list Bug-bash@gnu.org http://lists.gnu.org/mailman/listinfo/bug-bash
