expect命令

expect介绍

expect 是由 Don Libes 基于 Tcl（Tool Command Language）语言开发的，主要应用于自动化交互式操作的场景，借助 Expect 处理交互的命令，可以将交互过程如：ssh登录，ftp登录等写在一个脚本上，使之自动化完成。尤其适用于需要对多台服务器执行相同操作的环境中，可以大大提高系统管理人员的工作效率。

expect 语法：

expect [option] [-c cmds] [[-[f|b]] cmdfile] [args]

• 选项：
   -c：从命令行执行 expect 脚本，默认 expect 是交互地执行的
    expect -c expect "\n" {send "pressed enter\n"}
   -d：可以输出调试信息
    expect -d ssh.exp

• expect 中相关命令：
   spawn：启动新的进程
   send：用于向进程发送字符串
   expect：从进程接收字符串
   interact：允许用户交互
   exp_continue：匹配多个字符串在执行动作后加此命令

• expect 最常用的语法（tcl 语言：模式 - 动作）

• 单一分支模式语法：
  匹配到 hi 后，会输出 "You said hi"，并换行

  [root@node2 ~]# expect
  expect1.1> expect "hi" {send "You said hi\n"}
  hi
  You said hi
  

• 多分支模式语法：
  匹配 hi，hehe，bye 任意字符串时，执行相应输出

  [root@node2 ~]# expect
  expect1.1> expect "hi" { send "You said hi\n" } \
  +> "hehe" { send "Hehe yourself\n" } \
  +> "bye" { send "Good bye\n" }
  hi
  You said hi
  

  [root@node2 ~]# expect
  expect1.1> expect {
  +> "hi" { send "You said hi\n" }
  +> "hehe" { send "Hehe yourself\n" }  
  +> "bye" { send "Good bye\n" }
  +> }
  hi
  You said hi
  

示例：

1. 自动化远程复制文件

   #!/usr/bin/expect
   spawn scp /etc/fstab 192.168.8.100:/app
   expect {
           "yes/no" { send "yes\n";exp_continue }
           "password" { send "RyoATeu6\n" }
   }
   expect eof
   

2. 自动化登录

   #!/usr/bin/expect
   spawn ssh 192.168.8.100
   expect {
           "yes/no" { send "yes\n";exp_continue }
           "password" { send "RyoATeu6\n" }
   }
   interact
   

3. 变量

   #!/usr/bin/expect
   set ip 192.168.8.100
   set user root
   set password 88888888
   set timeout 10
   spawn ssh $user@$ip
   expect {
           "yes/no" { send "yes\n";exp_continue }
           "password" { send "$password\n" }
   }
   interact
   

4. 位置参数

   #!/usr/bin/expect
   set ip [lindex $argv 0]
   set user [lindex $argv 1]
   set password [lindex $argv 2]
   spawn ssh $user@$ip
   expect {
           "yes/no" { send "yes\n";exp_continue }
           "password" { send "$password\n" }
   }
   interact
   

5. shell脚本调用expect

   #!/bin/bash
   ip=$1
   user=$2
   password=$3
   expect <<EOF
   set timeout 10
   spawn ssh $user@$ip
   expect {
           "yes/no" { send "yes\n";exp_continue }
           "password" { send "$password\n" }
   }
   expect "]#" { send "useradd hehe\n" }
   expect "]#" { send "echo 88888888 | passwd --stdin hehe\n" }
   expect "]#" { send "exit\n" }
   expect eof
   EOF