一、Expect概述

　　Expect是一个免费的编程工具语言，用来实现自动和交互式任务进行通信，而无需人的干预。Expect的作者Don Libes在1990年开始编写Expect时对Expect做有如下定义：Expect是一个用来实现自动交互功能的软件套件 (Expect [is a] software suite for automating interactive tools)。

二、Expect工作原理

　　从最简单的层次来说，Expect的工作方式象一个通用化脚本工具。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。

　　　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。

三、安装

[root@localhost ~]# yum -y install expect tcl tclx tcl-devel

四、示例（解决人机交互的问题）

1.示例1：通过expect解决ssh交互问题（登录验证免交互）
[root@localhost ~]# vim ex.exp
#!/usr/bin/expect
spawn ssh root@10.8.161.173   //spawn  expect 内部命令，启动一个shell程序。
expect {                 //expect 期望哪些内容
 "yes/no" { send "yes\r" ; exp_continue }  //yes/no  就send发送 yes ，\r  表示回车 ;exp_continue，跳过循环，就继续下一条语句。
 "password:" { send "centos\r" };  //password 就send发送密码
}
interact   //interact 允许用户交互,保留对话

[root@localhost ~]# expect ex.exp    //运行脚本命令为expect
spawn ssh root@10.8.161.173
root@10.8.161.173's password: 

[root@localhost ~]# ip a   //远程登录成功，查看ip
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:58:e1:55 brd ff:ff:ff:ff:ff:ff
    inet 10.8.161.173/24 brd 10.8.161.255 scope global noprefixroute dynamic ens33
       valid_lft 257991sec preferred_lft 257991sec
    inet6 fe80::b253:d870:7f74:52c8/64 scope link tentative noprefixroute dadfailed 
       valid_lft forever preferred_lft forever
    inet6 fe80::7801:a245:f982:a228/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

2.示例2：expect实战：公钥推送
[root@localhost ~]# vim expect.sh 
#!/bin/bash
#创建一个IP地址文件
>ip.txt
#检测expect是否安装
rpm -q expect &> /dev/null
if [ $? -ne 0 ];then
yum install -y expect tcl tclx tcl-devel
fi
#检测公钥是否创建
if [ ! -f ~/.ssh/id_rsa ];then
ssh-keygen -P " " -f ~/.ssh/id_rsa
fi
ip=10.8.161.173
#ping测试主机是否在线
ping -c1 -W1 $ip &>/dev/null
if [ $? -eq 0 ];then
echo "$ip" >> ip.txt
/usr/bin/expect <<-EOF
set timeout 10
spawn ssh-copy-id $ip
expect {
"yes/no" {send "yes\r";exp_continue}
"password:" {send "centos\r"};
}
expect eof
EOF
fi

[root@localhost ~]# bash expect.sh 
spawn ssh-copy-id 10.8.161.173
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed

/usr/bin/ssh-copy-id: WARNING: All keys were skipped because they already exist on the remote system.
                (if you think this is a mistake, you may want to use -f option)

expect: spawn id exp6 not open
    while executing
"expect eof"

[root@localhost ~]# ssh root@10.8.161.173
Last login: Thu Jan  7 20:43:46 2021 from 10.8.161.66
[root@localhost ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:58:e1:55 brd ff:ff:ff:ff:ff:ff
    inet 10.8.161.173/24 brd 10.8.161.255 scope global noprefixroute dynamic ens33
       valid_lft 244538sec preferred_lft 244538sec
    inet6 fe80::b253:d870:7f74:52c8/64 scope link tentative noprefixroute dadfailed 
       valid_lft forever preferred_lft forever
    inet6 fe80::7801:a245:f982:a228/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

拓展：

yum list| grep expect //查看安装expect没
yum -y install expect //安装expect
rpm -ql expect