From: dusty <dusty.doris@...>
Date: 2007-11-28T08:20:00+09:00
Subject: Re: How to redirect a "system" standard output to a variable

On Nov 27, 3:58 pm, Venks <venkatesh.man...@gmail.com> wrote:
> Note:  parts of this message were removed by the gateway to make it a legal Usenet post.
>
> Hi,
>
> I need to redirect any standard output thrown when using a system call into
> a Ruby variable. I tried to search for a solution but couldn't find anything
> that worked. May be I am not using the right search terms.
>
> Here is what I am trying to do.
>
> begin
>
>   `rm somefile`
>
> end
>
> If "somefile" doesn't exist the OS throws the message "rm: cannot remove
> `somefile': No such file or directory" which I want to capture into a
> variable.
>
> Thanks,

I use open4 for things like that.  Try this it will show you how it
works.
http://codeforpeople.com/lib/ruby/open4/

# test.rb
require 'rubygems'
require 'open4'

commands = ["rm somefile","ls"]
commands.each do |command|
  status = Open4::popen4(command) do |pid,stdin,stdout,stderr|
    puts "Running command: #{command}\n\n"
    puts "pid:\n#{pid}"
    puts "\nstdout:\n#{stdout.read.strip}"
    puts "\nstderr:\n#{stderr.read.strip}"
  end
  puts "\nexitcode\n#{status.exitstatus}\n"
  puts "----------\n\n\n"
end

$ ruby test.rb
Running command: rm somefile

pid:
11207

stdout:

stderr:
rm: somefile: No such file or directory

exitcode
1
----------


Running command: ls

pid:
11208

stdout:
test.rb

stderr:

exitcode
0
----------