def runshell(command)
      logger.info "+ #{command}"
      output = `#{command} < #{null_device} 2>&1`
      raise StandardError, "Command failure: #{output}" unless $?.success?
      output
    end
def runshell(command)
      logger.info "+ #{command}"
      output = `#{command} < #{null_device} 2>&1`
      raise StandardError, "Command failure: #{output}" unless $?.success?
      output
    end
Run a system command

 === Raise
 StandardError:: if command fails

 === Return
 result(String):: output from the command