def process_shell_command
      command_line.set_prompt ':!'
      cmd = command_line.get_command(prompt: ':!')[1..-1]
      execute_external_command pause: true do
        system cmd
      end
    rescue Interrupt
    ensure
      command_line.clear
      command_line.noutrefresh
    end
def process_shell_command
      command_line.set_prompt ':!'
      cmd = command_line.get_command(prompt: ':!')[1..-1]
      execute_external_command pause: true do
        system cmd
      end
    rescue Interrupt
    ensure
      command_line.clear
      command_line.noutrefresh
    end
Accept user input, and directly execute it in an external shell.