首先创建一个expect脚本ssh_expect，文件内容如下：
#!/usr/bin/expect -f
set hostname [lindex $argv 0]
set user [lindex $argv 1]
set passwd [lindex $argv 2]
set timeout 30
set force_conservative 1
if {$force_conservative} {
set send_slow {128 .1}
}
spawn ssh $user@$hostname;
expect {
*continue connecting (yes/
