Expect是基于TCL的，作为一个脚本语言，expect能在无需管理员参与的情况下实现自动交互(比如passwd，fsck，telnet等)。expect也能用于自动测试一些应用程序。

这里博主以登陆路由器为例，先简单了解expect实现telnet自动登陆路由器的过程。当然也可以使用expect脚本ssh登陆服务器进行自动化管理。

#!/usr/bin/expect
spawn telnet 192.168.1.1
expect
"*Username:*"
send
"yourname\r"
expect
"*Password:*"
send
"yourpwd\r"
send
"en\r"
expect
"*password:*\r"
send
"yourpwd\r"
send
"sys show\r"
send
"exit\r"
expect eof

运行测试一切正常。

spawn telnet 192.168.1.1
Trying 192.168.1.1…
Connected to 192.168.1.1.
Escape character is ‘^]’.
Username:yourname
Password:

TP-LINK > en
Enter password:
TP-LINK # sys show
CPU Used Rate: 17%

TP-LINK > exit
Connection closed by foreign host.