From: Noah Easterly <noah.easterly@...>
Date: 2006-11-15T06:40:11+09:00
Subject: Re: backtick subshell

Ok, from skimming process.c in the ruby source, it looks like it's hard
coded to use 'sh', either through
calls to system (implicitly, since it forwards to sh by ISO standards),
execl (explicitly), or spawnl (explicitly),
except in the case of WIN_32, though, when it calls do_spawn, which i
think checks the RUBYSHELL environment variable.

Which is confusing. Can anyone lend me some clarity?

On Nov 14, 3:49 pm, "Noah Easterly" <noah.easte...@gmail.com> wrote:
> I don't think it's using the $SHELL variable to choose which shell to
> use (and I don't trust all the shells to set $SHELL)
>
> As an example:
>
> so here's a command that I get different responses on, depending on
> which shell it's run in
>
> sh-2.05b$ ls **/*.rb | wc -l
>        1
> sh-2.05b$ zsh -c "ls **/*.rb | wc -l"
>       12
>
> And in ruby backticks, I get the sh response
>
> sh-2.05b$ ruby -e "puts %x{ls **/*.rb | wc -l}"
>        1
>
> even when the $SHELL is set otherwise
>
> sh-2.05b$ export SHELL=/bin/zsh
> sh-2.05b$ echo $SHELL
> /bin/zsh
> sh-2.05b$ ruby -e "puts %x{echo $SHELL}"
> /bin/zsh
> sh-2.05b$ ruby -e "puts %x{ls **/*.rb | wc -l}"
>        1
>
> or if the ruby script is run by a different shell
>
> zsh: echo $SHELL
> /bin/zsh
> zsh: ruby -e "puts %x{echo $SHELL}"
> /bin/zsh
> zsh: ruby -e "puts %x{ls **/*.rb | wc -l}"
>        1
>
> So my question remains, how is ruby choosing which shell to use for
> backtick commands? (since in this case it really doesn't seem like it's
> checking $SHELL at all).
> I know I can force a choice of shell from within the backtick (ruby -e
> 'puts %x{/bin/sh -c "ls **/*.rb | wc -l"}'), but I want to know where
> ruby's getting its choice of shell from.
>
> On Nov 14, 2:56 pm, Paul Lutus <nos...@nosite.zzz> wrote:
>
> > Noah Easterly wrote:
> > > What subshell does ` (backquote) use to run commands?$ irb
> > irb(main):001:0> `echo $SHELL`
> > => "/bin/bash\n"
>
> > YMMV, depending on platform and version.
> 
> > --
> > Paul Lutushttp://www.arachnoid.com