Re: Update on parent exiting after background command substitution

[Joshua Neuheisel]

On 6/30/05, Chet Ramey <chet.ramey@case.edu> wrote:
>
> jneuheisel@gmail.com wrote:
> > Configuration Information [Automatically generated, do not change]:
> > Machine: i686
> > OS: linux-gnu
> > Compiler: gcc
> > Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='i686'
> -DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i686-pc-linux-gnu'
> -DCONF_VENDOR='pc' -DLOCALEDIR='/tmp/REMOVEME/LOCAL/share/locale'
> -DPACKAGE='bash' -DSHELL -DHAVE_CONFIG_H  -I.  
> -I/tmp/REMOVEME/bash-3.0-I/tmp/REMOVEME/bash-
> 3.0/include -I/tmp/REMOVEME/bash-3.0/lib   -g -O2
> > uname output: Linux hal.barc.equinoxsensors.com 2.6.11.11 #1 SMP Wed Jun
> 1 09:06:51 EDT 2005 i686 i686 i386 GNU/Linux
> > Machine Type: i686-pc-linux-gnu
> >
> > Bash Version: 3.0
> > Patch Level: 16
> > Release Status: release
> >
> > Description:
> >       I had previously sent a bug-report explaining that a parent bash
> > process would sometimes exit if a background interactive command was
> issued
> > that contained a process substitution.  I now have found the cause of
> the
> > problem, and detail that below.
> >
> > Repeat-By:
> >       Begin an interactive bash session.
> >       Execute the command "$(:|:)&", without the quotes.
> >       Continue to execute the above command until the parent shell
> > exits.
>
> This is a classic race condition.  It's already been fixed for the
> next version.
>


Some more (hopefully useful) debug info:
1. $(:|:)& still kills bash 3.1.5 with regularity.
2. I discovered that $(:|:)& will also kill bash 2.05b, but far more
infrequently.  At first I thought this bug started in bash 3.0, but it seems
to go back further than that.

The same reason still applies: the background shell incorrectly tries to set
the foreground group.

Joshua