From: Noah Easterly <noah.easterly@...>
Date: 2006-11-15T05:50:05+09:00
Subject: Re: backtick subshell

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