1 概述
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
2 语法
expect命令
expect 语法：
expect [选项] [ -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
示例：expect -c 'expect "\n" {send "pressed enter\n"}
-d：可以输出输出调试信息
示例：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：
expect “hi” {send “You said hi\n"}
匹配到hi后，会输出“you said hi”，并换行
多分支模式语法：
expect "hi" { send "You said hi\n" } \
"hehe" { send “Hehe yourself\n" } \
"bye" { send “Good bye\n" }
匹配hi,hello,bye任意字符串时，执行相应输出。等同如下：
expect {
"hi" { send "You said hi\n"}
"hehe" { send "Hehe yourself\n"}
"bye" { send “Good bye\n"}
}
3 脚本
以下是在expect在shell脚本中调用常用的几个用法，自动拷贝脚本，下发脚本，ssh 和telnet 连接远程主机.
#!/bin/bash
#
#******************************************************************************
#Author: Sunny
#Date: 2017-09-03
#FileName: scp.sh
#version: 1.0
#Your change info:
#Description: For
#Copyright(C): 2017 All rihts reserved
#*****************************************************************************
echo "1 copy wang home dir,usage:$0"
echo "2 copy file under wang home,usage: $0 file_to_copy"
echo "3 send file to wang home,usage: $0 file_to_send"
echo "4 login other host by ssh,usage: $0 login_ip"
echo "5 login other host by telnet,usage: $0 login_ip login_user"
read -p "input the remote ip: " ip
read -p "input full path file_name or dir: " file
read -p "input host password: " passwd
read -p "Please input your choice: " choice
case $choice in
1)
expect -c "
spawn scp -r root@$ip:$file "$file\_$(date +%F-%H-%M)"
expect {
# \"*assword\" {set timeout 300; send \"$passwd\r\"; }
\"*assword\" {set timeout 300; send \"$passwd\r\"; }
\"yes/no\" { send \"yes\r\"; exp_continue; }
}
expect eof"
;;
2)
expect -c "
spawn scp root@$ip:$file /root/
expect {
# \"*assword\" {set timeout 500; send \"$passwd\r\"; }
\"*assword\" {set timeout 500; send \"$passwd\r\"; }
\"yes/no\" { send \"yes\r\"; exp_continue; }
}
expect eof"
;;
3)
expect -c "
spawn scp $file root@$ip:/root
expect {
# \"*assword\" {set timeout 500; send \"$passwd\r\"; }
\"*assword\" {set timeout 500; send \"$passwd\r\"; }
\"yes/no\" { send \"yes\r\"; exp_continue; }
}
expect eof"
;;
4)
expect -c "
spawn ssh $ip
expect {
\"yes/no\" { send \"yes\r\"; exp_continue; }
\"*assword\" {set timeout 500; send \"$passwd\r\"; }
}
interact
expect eof"
;;
5)
expect -c "
spawn telnet $ip
expect {
\"*assword\" {set timeout 500; send \"$passwd\r\"; }
\"login\" { send \"sunny\r\";exp_continue; }
}
interact
expect eof"
;;
*)
echo "Your input is wrong,please check"
exit
;;
esac
4 总结
expect可以实际静默的操作，这个在脚本中经常用到，读者根据对应的功能，拷贝相关代码，可以直接把变量换成固定的值，不需要每次运行脚本都需要人工输入变量值，实现静默操作。
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