Putting things together for Pexpect

As the final step, let's put everything you learned so far for Pexpect into a script. Putting the code in a script makes it easier to use it in a production environment as well as share the code with your colleagues.

  #!/usr/bin/python3

  import getpass
  from pexpect import pxssh

  devices = {'iosv-1': {'prompt': 'iosv-1#', 'ip': '172.16.1.20'},
  'iosv-2': {'prompt': 'iosv-2#', 'ip': '172.16.1.21'}}
  commands = ['term length 0', 'show version', 'show run']

  username = input('Username: ')
  password = getpass.getpass('Password: ')

  # Starts the loop for devices
  for device in devices.keys():
      outputFileName = device + '_output.txt'
      device_prompt = devices[device]['prompt']
      child = pxssh.pxssh()
      child.login(devices[device]['ip'], username.strip(), password.strip(), auto_promp t_reset=False)
      # Starts the loop for commands and write to output
      with open(outputFileName, 'wb') as f:
          for command in commands:
              child.sendline(command)
              child.expect(device_prompt)
              f.write(child.before)

      child.logout()

The script further expands on our first Pexpect program with the following additional features:

• It use SSH instead of telnet
• It supports multiple commands instead of just one by making the commands into a list (line 8) and loop through the commands (starting line 20)
• It prompts the user for username and password instead of hardcoding them in the script
• It writes the output into a file to be further analyzed