shell编程之Expect
2021-06-25 本文已影响0人
肉包君
2021-01-13
expect的安装
[root@host ~]# yum -y install expect
expect应答函数的语法
是一个免费的编程工具, 用来实现自动的交互式任务, 而无需人为干预. 说白了expect就是一套用来实现自动交互功能的软件
在实际工作中我们运行命令、脚本或程序时, 这些命令、脚本或程序都需要从终端输入某些继续运行的指令,而这些输入都需要人为的手工进行. 而利用expect则可以根据程序的提示, 模拟标准输入提供给程序, 从而实现自动化交互执行. 这就是expect
能够在工作中熟练的使用Shell脚本就可以很大程度的提高工作效率, 如果再搭配上expect,那么很多工作都可以自动化进行,对工作的展开如虎添翼
用法：
1）定义脚本执行的shell
#!/usr/bin/expect 类似于#!/bin/bash
2）set timeout 30
设置超时时间30s
3）spawn
spawn是进入expect环境后才能执行的内部命令，不能直接在默认的shell环境中执行
功能：传递交互命令
4）expect
这里的expect同样是expect命令
功能：判断输出结果是否包含某项字符串，没有则立即返回，否则等待一段时间后返回，等待通过timeout设置
5）send
执行交互动作，将交互要执行的动作进行输入给交互指令
命令字符串结尾要加上“r”，如果出现异常等待状态可以进行核查
6）interract
执行完后保持交互状态，把控制权交给控制台
如果不加这一项，交互完成会自动退出
7）exp_continue
继续执行接下来的操作
expect环境中设置变量用set，识别不了bash方式定义的变量
错误方式：
[root@host expect]# cat expect02.sh
#!/usr/bin/expect
user=22
spawn echo $user
[root@host expect]# ./expect02.sh
invalid command name "user=22"
while executing
"user=22"
(file "./expect02.sh" line 3)
正确方式：
[root@host expect]# cat ./expect02.sh
#!/usr/bin/expect
set user 22
spawn echo $user
[root@host expect]# ./expect02.sh
spawn echo 22
============================================================================
[root@host expect]# cat expect01.sh
#!/usr/bin/expect
spawn ssh root@192.168.62.146
expect {
"yes/no" { send "yes\r";exp_continue }
"password:" { send "123\r" }
}
interact
interact的作用测试
执行测试是否免交互：
要是用/usr/bin/expect的shell执行
[root@host expect]#/usr/bin/expect expect01.sh
成功
擦除最后一行interact进行测试
[root@host expect]#/usr/bin/expect expect01.sh
进入之后立即退出
============================================================================
\r的作用测试
[root@host expect]# cat expect01.sh
#!/usr/bin/expect
set user root
set pass 123
set ip 192.168.62.146
spawn ssh $user@$ip
expect {
"yes/no" { send "ye";exp_continue }
"password:" { send "pas" }
}
interact
[root@host expect]# ./expect01.sh
spawn ssh root@192.168.62.146
root@192.168.62.146's password:
加上\r之后
[root@host expect]# ./expect01.sh
spawn ssh root@192.168.62.146
root@192.168.62.146's password:
Permission denied, please try again.
root@192.168.62.146's password:
============================================================================
设置变量的方式
[root@host expect]# cat expect01.sh
#!/usr/bin/expect
set user root
set pass 123
set ip 192.168.62.146
spawn ssh $user@$ip
expect {
"yes/no" { send "yes\r";exp_continue }
"password:" { send "$pass\r" }
}
interact
实现ssh自动登录----expect的常用实例
#!/usr/bin/env expect
#
# Author:
set password "123"
set username "root"
spawn ssh $username@192.168.161.130
expect "*yes/no*" {send "yes\r"}
expect "*password*" {send "$password"}
实现自动生成密钥
[root@host ~]# ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Created directory '/root/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:C+buJw3dkFuyWCTXWGr9oSHjoaLeZzMfonA0Vj/BbW0 root@nginxserver02
The key's randomart image is:
+---[RSA 2048]----+
| +. |
| ..++.. |
| .+O.= E |
| . ==*.= . |
| = ++SB. . |
| + =o.+o. |
| o . ooo |
| . + o*.o. |
| . o+o*. |
+----[SHA256]-----+
[root@host ~]# vim no_enter_sshkey
#!/usr/bin/env expect
#
# Author:
spawn ssh-keygen
expect "*):*" {send "\r"}
expect "*passphrase*" {send "\r"}
expect "*again*" {send "\r"}
expect eof
将expect函数嵌入shell脚本
/usr/bin/expect <<-EOF
set password "123"
set username "root"
spawn ssh $username@192.168.161.130
expect "*yes/no*" {send "yes\r"}
expect "*password*" {send "$password"}
EOF
设置位置参数的方式(拓展)
[root@host expect]# cat expect01.sh
#!/usr/bin/expect
set timeout 30
set user [ lindex $argv 0 ]
set pass [ lindex $argv 1 ]
set ip [ lindex $argv 2 ]
spawn ssh $user@$ip
expect {
"yes/no" { send "yes";exp_continue }
"password:" { send "$pass\r" }
}
interact
运行结果为：
[root@host expect]# ./expect01.sh root 123 192.168.62.146
spawn ssh root@192.168.62.146
root@192.168.62.146's password:
Last login: Thu Aug 15 23:26:59 2019 from 192.168.62.136
