Expect自动化SSH管理-优快云博客

expect简单用法转载自：http://yujia2016.blog.51cto.com/59379/1760924 下期预告：Centos7安装配置phpmyadmin 在现今高度发展的it社会，已经有很多的自动化管理程序了，例如Puppet，Salt，func，Capistrano …….而且还有云虚拟化OpenStack,kvm,xen…..尤其Docker更是新生代黑马，为自动化管理而生的。但存在即为合理，你有高大上，我也有土肥圆，相对于快捷，简单的管理小批量linux机器，ssh和expect是非常好用的 Expect是什么他是一枚程序，是基于uucp（Unix to Unix Copy Protocol）的发送/预期的序列设计而来的。 The name “Expect” comes from the idea of send/expect sequences popularized by uucp, kermit and other modem control programs. However unlike uucp, Expect is generalized so that it can be run as a user-level command with any program and task in mind. Expect can actually talk to several programs at the same time. For example, here are some things Expect can do: Cause your computer to dial you back, so that you can login without paying for the call. Start a game (e.g., rogue) and if the optimal configuration doesn’t appear, restart it (again and again) until it does, then hand over control to you. Run fsck, and in response to its questions, answer “yes”, “no” or give control back to you, based on predetermined criteria. Connect to another network or BBS (e.g., MCI Mail, CompuServe) and automatically retrieve your mail so that it appears as if it was originally sent to your local system. Carry environment variables, current directory, or any kind of information across rlogin, telnet, tip, su, chgrp, etc. 从最简单的层次来说，Expect的工作方式象一个通用化的Chat脚本工具。Chat脚本最早用于UUCP网络内，以用来实现计算机之间需要建立连接时进行特定的登录会话的自动化。 Chat脚本由一系列expect-send对组成：expect等待输出中输出特定的字符，通常是一个提示符，然后发送特定的响应。例如下面的Chat脚本实现等待标准输出出现Login:字符串，然后发送somebody作为用户名；然后等待Password:提示符，并发出响应sillyme。

所以expect的工作流程是类似聊天的流程： A跟B说 hello B发现A跟他说hello，然后就回复hi然后A XXXXX然后B 发现A 在说XXXXX，所以就回复OOOOO....... 理解的话可以这样理解，虽然不够完整，但不失其意义。然后既然知道了expect是怎么起作用的，那么的话就可以构思我们的自动化管理设计了，因为expect的设计原理就是为了去处理“交互式”，把“交互式”处理之后，人为的干预就少了,自然就实现自动化了。一般的expect 使用 #!/usr/bin/expectset timeout 5 spawn ssh 192.168.6.136 -p 1024 expect "password" send "123passwd\r" expect "Last login" send " ifconfig |grep eth0 -A3\r" expect eof exit #!/usr/bin/expect是调用expect的写法，这个跟一般的shell 写 #!/bin/bash是不同的，这里的意义是以下内容是以什么方式运行，写expect就是expect的方式，写bash就是bash。 spawn是创建一个进程，就是使用expect的时候是要运行expect进程的，spwan就是代表需要创建这样的进程的意思，理解为create也可以，这里就是创建一个ssh 连接的进程，后面的写法跟一般ssh连接执行命令无异。 timeout 表示这个expect动作的生存时间，根据我的理解，例如设置为5秒，那么执行一次expect后就要等待5秒。 expect eof和exit是指监测到eof就会执行exit，退出程序。高端一点点可以改为…… 我们观察一般的ssh正常交互会有哪些情况，首次连接提示，成功连接后会生成knowhost，以后就不会提示了。 ssh 192.168.6.136 -p 1024 The authenticity of host '[192.168.6.136]:1024 ([192.168.6.136]:1024)' can't be established. RSA key fingerprint is 7d:68:97:bc:f8:c1:b7:8a:a9:98:5a:03:4a:77:b9:eb. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added '[192.168.6.136]:1024' (RSA) to the list of known hosts. root@192.168.6.136's password: 正常连接提示： ssh 192.168.6.136 -p 1024root@192.168.6.136's password: 连接被拒绝，可能是ssh没开，或者端口不对，或者iptables限制： ssh 192.168.6.136 ssh: connect to host 192.168.6.136 port 22: Connection refused 没有连接地址： ssh sadas ssh: Could not resolve hostname sadas: Name or service not known

所以可以改成这样： #!/usr/bin/expectset timeout 5 spawn ssh 192.168.6.136 -p 1024 expect { "Connection refused" exit "Name or service not known" exit "continue connecting" {send "yes\r";exp_continue} "password:" {send "123passwd\r";exp_continue} "Last login" {send " ifconfig |grep eth0 -A3\n"}} expect eof exit 将所以的expect收集为一个，然后使用类似switch-case的模式，匹配哪个就触发哪个，并且需要执行下一步动作的则需要加上exp_continue，其实这里就跟普通程序里面的控制循环的continue是一样的用法的。这是执行结果： [root@localhost test_shell_expect]# ./test3.sh spawn ssh 192.168.6.136 -p 1024 root@192.168.6.136's password: Last login: Wed Feb 25 07:07:42 2015 from 192.168.6.127 [root@wohost ~]# ifconfig |grep eth0 -A3 eth0 Link encap:Ethernet HWaddr 00:0C:29:DE:E9:90 inet addr:192.168.6.136 Bcast:192.168.6.255 Mask:255.255.255.0 inet6 addr: fe80::20c:29ff:fede:e990/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 再高端一点点可以这样，支持变量定义和传参功能 #!/usr/bin/expect set timeout 5 set pw "123passwd" set host [lindex $argv 0] spawn ssh $host -p 1024expect { "Connection refused" exit "Name or service not known" exit "continue connecting" {send "yes\r";exp_continue} "password:" {send "$pw\r";exp_continue} "Last login" {send " ifconfig |grep eth0 -A3\n"}} expect eof exit set就是用来变量定义的，而传参的话就是使用一个lindex $argv 0 的方式，$argv是指参数项数组，lindex将参数项数组的列表生成出来，然后 0 代表的是使用第一个值，不过这里有个小疑问我还没有完全理解，就是参考debug模式可以看到argv[0] = /usr/bin/expect argv[1] = -d argv[2] = ./test3.sh argv[3] = 192.168.6.136 ，第一个值应该argv[0] = /usr/bin/expect才对，但是程序能够获取到192.168.6.136，我暂时的理解就是他读取的是我执行命令的第一个参数，例如./test3.sh 192.168.6.136，所以第一个参数就是192.168.6.136，如此类推。效果： ./test3.sh 192.168.6.136 spawn ssh 192.168.6.136 -p 1024 root@192.168.6.136's password: Last login: Wed Feb 25 07:11:17 2015 from 192.168.6.127 ifconfig |grep eth0 -A3 [root@wohost ~]# ifconfig |grep eth0 -A3 eth0 Link encap:Ethernet HWaddr 00:0C:29:DE:E9:90 inet addr:192.168.6.136 Bcast:192.168.6.255 Mask:255.255.255.0 inet6 addr: fe80::20c:29ff:fede:e990/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 然后配合shell做个循环就可以简单实现批量管理 [root@localhost test_shell_expect]# cat test2.sh #!/bin/bashwhile read hostdo ./test1.exp $host done <file.txt [root@localhost test_shell_expect]# cat file.txt log test1.exp test2.sh test3.sh [root@localhost test_shell_expect]# cat file.txt 192.168.6.136192.168.6.127 大功告成。 troubleshooting 打开debug模式，使用-d，可以方便调试并且观看expect的执行过程。 #!/usr/bin/expect -d 输出效果如下： ./test3.sh 192.168.6.136 expect version 5.44.1.15 argv[0] = /usr/bin/expect argv[1] = -d argv[2] = ./test3.sh argv[3] = 192.168.6.136 set argc 1set argv0 "./test3.sh"set argv "192.168.6.136"executing commands from command file ./test3.sh spawn ssh 192.168.6.136 -p 1024parent: waiting for sync byteparent: telling child to go ahead parent: now unsynchronized from child spawn: returns {7991}expect: does "" (spawn_id exp4) match glob pattern "Connection refused"? no"Name or service not known"? no"continue connecting"? no"password:"? no"Last login"? noroot@192.168.6.136's password: expect: does "root@192.168.6.136's password: " (spawn_id exp4) match glob pattern "Connection refused"? no "Name or service not known"? no "continue connecting"? no "password:"? yes expect: set expect_out(0,string) "password:" expect: set expect_out(spawn_id) "exp4" expect: set expect_out(buffer) "root@192.168.6.136's password:" send: sending "123passwd\r" to { exp4 } expect: continuing expect expect: does " " (spawn_id exp4) match glob pattern "Connection refused"? no "Name or service not known"? no "continue connecting"? no "password:"? no "Last login"? no expect: does " \r\n" (spawn_id exp4) match glob pattern "Connection refused"? no "Name or service not known"? no "continue connecting"? no "password:"? no "Last login"? no Last login: Wed Feb 25 07:14:06 2015 from 192.168.6.127 expect: does " \r\nLast login: Wed Feb 25 07:14:06 2015 from 192.168.6.127\r\r\n" (spawn_id exp4) match glob pattern "Connection refused"? no "Name or service not known"? no "continue connecting"? no "password:"? no "Last login"? yes expect: set expect_out(0,string) "Last login" expect: set expect_out(spawn_id) "exp4" expect: set expect_out(buffer) " \r\nLast login" send: sending " ifconfig |grep eth0 -A3\n" to { exp4 } ifconfig |grep eth0 -A3 [root@wohost ~]# ifconfig |grep eth0 -A3 eth0 Link encap:Ethernet HWaddr 00:0C:29:DE:E9:90 inet addr:192.168.6.136 Bcast:192.168.6.255 Mask:255.255.255.0 inet6 addr: fe80::20c:29ff:fede:e990/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1

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转载于:https://my.oschina.net/u/3363053/blog/1537957