text: import subprocess
  
  print('$ nslookup')
  p = subprocess.Popen(['nslookup'], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
  output, err = p.communicate(b'set q=mx\npython.org\nexit\n')
  print(output.decode('utf-8'))
  print('Exit code:', p.returncode)
  
  '''
  如果子进程还需要输入，则可以通过communicate()方法输入：...
  上面的代码相当于在命令行执行命令nslookup，然后手动输入：
  
  set q=mx
  python.org
  exit
  运行结果如下：
  
  $ nslookup
  Server:        192.168.19.4
  Address:    192.168.19.4#53
  
  Non-authoritative answer:
  python.org    mail exchanger = 50 mail.python.org.
  
  Authoritative answers can be found from:
  mail.python.org    internet address = 82.94.164.166
  mail.python.org    has AAAA address 2001:888:2000:d::a6
  
  
  Exit code: 0
  '''