call bash from ruby code

ruby_bash.rb

require 'posix/spawn' # https://github.com/rtomayko/posix-spawn
require 'shellwords'

# thanks to:
# http://blog.honeybadger.io/capturing-stdout-stderr-from-shell-commands-via-ruby/
# http://greyblake.com/blog/2013/09/21/how-to-call-bash-not-shell-from-ruby/
# https://github.com/rtomayko/posix-spawn
def bash(command)
  escaped_command = Shellwords.escape(command)
  pid, stdin, stdout, stderr = POSIX::Spawn.popen4("bash -c #{escaped_command}")
  begin
    stdin.close
    result = stdout.read
  ensure
    exit_code = Process::waitpid2(pid)[1]
    stderr_msg = exit_code == 0 ? '' : stderr.read
    [stdin, stdout, stderr].each { |io| io.close if !io.closed? }
    raise StandardError, "Cmd failed: #{stderr_msg}" if exit_code != 0
  end
  result
end