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Re: Zsh 4.3.12: subshell in midnight commander: precmd: 15: bad file descriptor

On Mon, 18 Jul 2011 10:26:27 +0200
Pavel Reznicek <reznicek@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>    after upgrading to zsh 4.3.12 (in debian), I am having problems running 
> midnight commander in zsh (going back to zsh version 4.3.10 it works 
> fine). The symptom is that when trying to use the subshell in mc, it 
> complains about:
> precmd: 15: bad file descriptor
> and the mc session get hanged. Of course it could be bug in mc and not 
> zsh, but since this behaviour is not seen with zsh 4.3.10, the zsh updates 
> since that version can tell what is going on. Browsing the mc source code, 
> the precmd command defined in there is:
> precmd(){ pwd>&%d;kill -STOP $$ }
> Would some have an idea why this precmd command would cause the error 
> message above in connection of the updateds between zsh 4.3.10 and 4.3.12 
> ?

So if it's not (obviously) related to the "stop", we probably need to
know what file descriptor is appearing there.  If it's 1 or 2 there's
not obvious reason for parametrising it.  If it's not, it's not obvious
what it would be --- something opened by mc, presumably, and possibly
getting FD_CLOEXEC set, if the problem only occurs in subshells.

Hmm... if it were the shell terminal output, this fix spotted by Bart
might be relevant:

    * 27134: Src/exec.c, Src/init.c: improve 27131 by setting
      FD_CLOEXEC for SHTTY or closing it by hand when executing.

but SHTTY isn't directly exposed to the shell user (which is why
we're closing it).


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