runix: The ruby shell command executor you've always wanted.

runix.rb

# Ruby + UNIX = runix
#
# If return status is 0, returns standard out.
# If return status is non-0, raises an exception with standard error in the message.
# (None of the other methods you know about have this behavior)
#
# Great overview of all ruby shell methods:
#   http://tech.natemurray.com/2007/03/ruby-shell-commands.html
#
# dependency: open4 gem

require 'open4'

def runix(command)
  standard_error_message=nil
  out=""
  status = Open4::popen4(command) do |p, sin, sout, serr|
    standard_error_message=serr.read
    out = sout.read
  end

  # Open4.popen4 will raise an exception in some non-0 return states, but not all
  unless 0 == status
    raise "The shell command:\n\n#{command}\n\nfailed with status #{status} and this message:\n\n#{standard_error_message}\n\n"
  end
  out
end

/cc @ahoward :-)