Jusene's Blog

Python运维自动化利器pexpect

python
字数统计: 514阅读时长: 2 min
2018/02/07 Share

pexcept

pexcept是一个纯python实现的模块,pexpect可以某些交互式子进程进行交互而不需要手工操作,比如使用passwd命令时需要人工输入密码,而pexcept可以使用sendline进行自动化。

安装

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pip install -U pexpect

or

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easy_install pexpect

使用

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import pexpect
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child=pexpect.spawn('ssh root@10.211.55.18')
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'''
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The authenticity of host '10.211.55.18 (10.211.55.18)' can't be established.
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ECDSA key fingerprint is SHA256:FUUxzLdqAZQtRp5e0LeuwrQ698D3sDs3PoX9Fq3+uYk.
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Are you sure you want to continue connecting (yes/no)?
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'''
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child.expect('.*(yes/no)? ')
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child.sendline('yes')
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'''
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root@10.211.55.18's password:
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'''
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child.expect('password: ')
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child.sendline('123456')
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print(child.before)
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b"root@10.211.55.18's "  #before属性将包含所有的文本到预期的字符串模式
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print(child.after)
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b'password: '            #after属性将包含与预期模式匹配的文本
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child.interact()         #给出子进程的控制权
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Last login: Wed Feb  7 00:20:45 2018 from 10.211.55.2
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[root@node3 ~]#

except() 可以是正则表达式，也可能是正则表达式的列表。这允许您匹配多个可选响应。

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import pexpect
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secret='123456'
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child=pexpect.spawn('ssh root@10.211.55.18')
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child.expect('password: ')
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child.sendline(secret)
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i = child.expect(['password: ','\[.*\]# '])
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if i==0:
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    print('密码错误')
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    child.kill(0)
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elif i==1:
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    print('登陆成功')
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    child.interact()

except()超时等待时间，默认是30秒，可以通过参数的形式更改:

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child.expect('password: ',timeout=120)

debug

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import pexpect
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secret='12345'
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child=pexpect.spawn('ssh root@10.211.55.18')
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child.expect('password: ')
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child.sendline(secret)
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print(str(child))
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<pexpect.pty_spawn.spawn object at 0x105ee30b8>
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command: /usr/bin/ssh
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args: ['/usr/bin/ssh', 'root@10.211.55.18']
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buffer (last 100 chars): b''
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before (last 100 chars): b"root@10.211.55.18's "
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after: b'password: '
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match: <_sre.SRE_Match object; span=(20, 30), match=b'password: '>
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match_index: 0
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exitstatus: None
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flag_eof: False
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pid: 7922
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child_fd: 5
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closed: False
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timeout: 30
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delimiter: <class 'pexpect.exceptions.EOF'>
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logfile: None
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logfile_read: None
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logfile_send: None
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maxread: 2000
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ignorecase: False
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searchwindowsize: None
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delaybeforesend: 0.05
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delayafterclose: 0.1
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delayafterterminate: 0.1
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child.expect('password: ')
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print(str(child))
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<pexpect.pty_spawn.spawn object at 0x105ee3400>
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command: /usr/bin/ssh
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args: ['/usr/bin/ssh', 'root@10.211.55.18']
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buffer (last 100 chars): b''
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before (last 100 chars): b"\r\nPermission denied, please try again.\r\r\nroot@10.211.55.18's "
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after: b'password: '
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match: <_sre.SRE_Match object; span=(61, 71), match=b'password: '>
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match_index: 0
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exitstatus: None
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flag_eof: False
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pid: 7936
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child_fd: 5
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closed: False
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timeout: 30
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delimiter: <class 'pexpect.exceptions.EOF'>
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logfile: None
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logfile_read: None
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logfile_send: None
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maxread: 2000
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ignorecase: False
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searchwindowsize: None
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delaybeforesend: 0.05
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delayafterclose: 0.1
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delayafterterminate: 0.1

原文作者：Zhang Jusene

原文链接：http://jusene.github.io/2018/02/07/pexpect/

发表日期：February 7th 2018, 10:36:13 pm

更新日期：November 30th 2019, 1:54:24 am

版权声明：本文采用知识共享署名-非商业性使用 4.0 国际许可协议进行许可

CATALOG
  1. 1. pexcept
  2. 2. 安装
  3. 3. 使用
  4. 4. debug
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