From: Logan Capaldo <logancapaldo@...>
Date: 2006-08-01T21:34:32+09:00
Subject: Re: Default shell for Kernel::system() ?


On Aug 1, 2006, at 4:20 AM, Ronald Fischer wrote:

> Ist it possible to kind of define a default shell which will be used
> for Kernel::system? I often need to invoke from my Ruby scripts
> external commands, involving redirection and globbing, for example
> (bash syntax)
>
>    foo [a-z]* 2>&-
>    bar <<<baz
>
> etc. Since these syntactic elements are shell specific, I need to
> specify the shell somehow, for example:
>
>    system("bash --norc -c 'foo [a-z]* 2>&-'")
>    system("bash --norc -c 'bar <<<baz'")
>
> which is a bit cumbersome. Of course one obvious solution would be
> to define a new function:
>
>    def bash(cmd)
>      system("bash --norc -c '"+cmd+"'")
>    end
>
> And use instead
>
>    bash('foo [a-z]* 2>&-')
>    bash('bar <<<baz')
>
> But this solution has two drawbacks:
>
> First one has to pay special attention that the shell command  
> itself should no contain single quotes. For example, it is all too  
> tempting
> to write a call
>
>    bash("my_command 'one argument'")
>
> which looks correct at first sight, but will have a different
> effect than
>
>    bash('my_command "one argument"')
>
> due to the interference between Ruby- and bash quoting.
>
> Another drawback of this solution is that one has to include the
> definition of the "bash" function with each Ruby script.
>
> So I wonder whether there is may be a simple, builtin solution
> for this problem - say, a way to specify the "default shell" used
> for system().
>
> Ronald
>
> -- 
> Ronald Fischer <ronaldf@eml.cc>
> Posted via http://www.newsoffice.de/
>
>

I'm pretty sure the "default" shell for system is /bin/sh on a *nix.