From: Hee-Sob Park <phasis@...>
Date: 2001-05-09T18:10:09+09:00
Subject: [ruby-talk:14905] Re: Backslashes in Backquotes


"Ashley Yakeley" <ashley@semantic.org> wrote in message
news:ashley-F346B5.22342308052001@news.halcyon.com...
> Is there an easy way in Ruby to execute a string as a command in a
> subshell and return the output text? 'System' doesn't seem to have this
> kind of redirection of output.
>
> I know, I'm probably missing something obvious. But I've been through
> the documentation and I couldn't find it...
>
> My first attempt looked like this:
>
>     def subshell(command)
>         `command`
>     end
>
> That doesn't work, because while `` does execute in a subshell, it also
> (annoying) quotes its content like a string literal. So I tried this:
>
>     def subshell(command)
>         eval '`'+command+'`'
>     end
>
> You'd think that would work, right? But no, Ruby insists on doing this
> weird control-character interpretation of \1, \2 etc. Try this from irb:
>
...
>
> So, there's no obvious way of passing the string "echo \1" to the shell.
> This is a trivial example, but it's a real pain for something like a
> regular expression passed as a command-line argument to sed.
>

Try this:

def subshell(command)
  puts `#{command}`
end

subshell('echo \1')


> --
> Ashley Yakeley, Seattle WA

Park Hee-Sob