Python安装使用命令行交互模块pexpect的基础教程-Python Tutorial-php.cn

一、安装
1、安装easy_install工具

wget http://peak.telecommunity.com/dist/ez_setup.py

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python ez_setup.py 安装easy_install工具（这个脚本会自动去官网搜索下载并安装）

python ez_setup.py -U setuptools

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升级easy_install工具

2、安装pexpect

easy_install Pexpect

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测试一下:

[root@OMS python]# python
Python 2.7.3rc1 (default, Nov 7 2012, 15:03:45)
[GCC 4.1.2 20080704 (Red Hat 4.1.2-48)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import pexpect
>>> import pxssh
>>>

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ok已经安装完成。

二、基本用法
1.run()函数
run功能相对简单，只能实现简单交互

复制代码代码如下:

run(command,timeout=-1,withexitstatus=False,events=None,extra_args=None, logfile=None, cwd=None, env=None)

run运行命令，然后返回结果，与os.system类似.
示例：

pexpect.run('ls -la')
# 返回值(输出，退出状态)
(command_output, exitstatus) = pexpect.run('ls -l /bin', withexitstatus=1)

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2.spawn类
spawn功能比run强大，可以实现更复杂交互

class spawn 
  __init__(self, command, args=[], timeout=30, maxread=2000, searchwindowsize=None, logfile=None, cwd=None, env=None)

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timeout指定交互是等待的超时值；
maxread设置read buffer大小. 每次pexpect尝试从TTY(Teletype终端)从读取的最大字节数；

searchwindowsize 指定了从输入缓冲区中进行模式匹配的位置，默认从开始匹配；

logfile 参数指定日志的记录位置。
工作过程：

# 第一步与终端建立连接
child = pexpect.spawn('scp foo user@example.com:.')
# 第二步等待终端返回特定内容
child.expect('Password:')
# 第三步根据返回内容发送命令进行交互
child.sendline(mypassword)

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3.pxssh类
pxssh是pexpect的派生类，用于建立ssh连接，比pexpect好用。

三、实例
写一个脚本给远程服务器发送命令，并返回结果。
脚本内容:

#!/usr/bin/python 
#2013-01-16 by larry 
import pexpect 
def login(port,user,passwd,ip,command): 
  child=pexpect.spawn(&#039;ssh -p%s %s@%s "%s"&#039; %(port,user,ip,command)) 
  o=&#039;&#039; 
  try: 
    i=child.expect([&#039;[Pp]assword:&#039;,&#039;continue connecting (yes/no)&#63;&#039;]) 
    if i == 0: 
      child.sendline(passwd) 
    elif i == 1: 
      child.sendline(&#039;yes&#039;) 
    else: 
      pass 
  except pexpect.EOF: 
    child.close() 
  else: 
    o=child.read() 
    child.expect(pexpect.EOF) 
    child.close() 
  return o 
 
hosts=file(&#039;hosts.list&#039;,&#039;r&#039;) 
for line in hosts.readlines(): 
  host=line.strip("\n") 
  if host: 
    ip,port,user,passwd,commands= host.split(":") 
    for command in commands.split(","): 
      print "+++++++++++++++ %s run:%s ++++++++++++" % (ip,command), 
      print login(port,user,passwd,ip,command)  
hosts.close()

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使用方法:

python scripts.py

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host.list文件内容如下:

192.168.0.21:22999:root:123456:cat /etc/redhat-release,df -Th,whoami
192.168.0.21:22999:root:123456:cat /etc/redhat-release,df -Th,whoami

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返回结果:

+++++++++++++++ 192.168.0.21 run:cat /etc/redhat-release ++++++++++++
Red Hat Enterprise Linux Server release 4
+++++++++++++++ 192.168.0.21 run:df -Th ++++++++++++
文件系统   类型  容量 已用 可用 已用% 挂载点
/dev/cciss/c0d0p6
ext3  5.9G 4.4G 1.2G 80% /
/dev/cciss/c0d0p7
ext3  426G 362G  43G 90% /opt
/dev/cciss/c0d0p5
ext3  5.9G 540M 5.0G 10% /var
/dev/cciss/c0d0p3
ext3  5.9G 4.1G 1.5G 74% /usr
/dev/cciss/c0d0p1
ext3  487M  17M 445M  4% /boot
tmpfs    tmpfs  4.0G   0 4.0G  0% /dev/shm
+++++++++++++++ 192.168.0.21 run:whoami ++++++++++++
root

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Related labels：

linux python shell Command Line

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