Python安装使用命令行交互模块pexpect的基础教程
一、安装
1、安装easy_install工具
wget http://peak.telecommunity.com/dist/ez_setup.py
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
升级easy_install工具
2、安装pexpect
easy_install Pexpect
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 >>>
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
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)
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)
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；
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)
3.pxssh类
pxssh是pexpect的派生类，用于建立ssh连接，比pexpect好用。
login() 建立到目标机器的ssh连接；
logout() 释放该连接；
prompt() 等待提示符，通常用于等待命令执行结束。
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('ssh -p%s %s@%s "%s"' %(port,user,ip,command))
o=''
try:
i=child.expect(['[Pp]assword:','continue connecting (yes/no)?'])
if i == 0:
child.sendline(passwd)
elif i == 1:
child.sendline('yes')
else:
pass
except pexpect.EOF:
child.close()
else:
o=child.read()
child.expect(pexpect.EOF)
child.close()
return o
hosts=file('hosts.list','r')
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()
使用方法:
python scripts.py
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
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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