expect实现自动交互由浅入深

expect实现自动交互由浅入深

作为运维人员可以通过Shell可以实现简单的控制流功能，如：循环、判断等。但是对于需要交互的场合则必须通过人工来干预，有时候我们可能会需要实现和交互程序如telnet服务器等进行交互的功能。而Expect就使用来实现这种功能的工具。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。

安装expect,直接yum install expect -y

expect中相关命令

命令	解释
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

一般步骤：

启动expect进程（spawn）--> 接收进程字符串(expect) --> 匹配字符串，成功发送字符串(send)，否则等待 --> 结束

好了就直接步入主题吧，不扯那些没用的。直接上实例：

一. 入门例子：实现自动登录

[root@localhost shell.sh]# vim test.exp
#!/usr/bin/expect
set timeout 30
spawn ssh -l root 192.168.1.106
expect {
"(yes/no)?" { send "yes\r" }
"password:" { send "jiajie\r" }
}
interact

参数	解释
#!/usr/bin/expect	说明使用的shell环境
set timeout 30	设置超时时间，单位为秒，-1为没有限制
spawn ssh...	需要执行的命令,这里是ssh登陆命令
expect "(yes/no)?"	判断上次输出结果里是否包含(yes/no)?的字符串
send "yes\r"	执行交互动作，接轨上一个命令，如果上面的expect执行成功，则发送yes
interact	执行完成后保持交互状态，把控制权交给控制台

执行该实例：./test.exp

如果报错-bash: ./test.exp: Permission denied,给744权限即可。

二. 使用变量：

[root@localhost shell.sh]# vim test.exp

#!/usr/bin/expect
set ip 192.168.1.106
set user root
set password jiajie
set timeout 30
spawn ssh -l $user $ip
expect {
"(yes/no)?" { send "yes\r";exp_continue }
"password:" { send "$password\r" }
}
interact

set:设置变量，后面直接变量，通过“$变量名”来调用

三. 使用位置参数：

[root@localhost shell.sh]# vim test.exp 
#!/usr/bin/expect
if {$argc!=3} {
        send_user "Usage:expect need three arguments:ip user password\n"
        exit 1
}
set ip [lindex $argv 0]
set user [lindex $argv 1]
set password [lindex $argv 2]
set timeout 30
spawn ssh -l $user $ip
expect {
"(yes/no)?" { send "yes\r";exp_continue }
"password:" { send "$password\r" }
}
interact

[lindex $argv num]：表示位置参数，从num=0开始

send_user: 打印当前提示，相当于shell里的echo.

四. 执行多个命令：

[root@localhost shell.sh]# vim test.exp 
#!/usr/bin/expect
if {$argc!=3} {
        send_user "Usage:expect need three arguments:ip user password\n"
        exit 1
}
set ip [lindex $argv 0]
set user [lindex $argv 1]
set password [lindex $argv 2]
set timeout 30
spawn ssh -l $user $ip
expect {
"(yes/no)?" { send "yes\r";exp_continue }
"password:" { send "$password\r" }
}
expect "]#" { send "useradd jj\r" }
expect "]#" { send "echo jiajie|passwd --stdin jj\r" }
send "exit\r"
expect eof
exit -onexit {
        send_user "useradd jj is successfully.\n"
        send_user "Jobs has finished,Goodbye.\n"
}

执行后的结果输出：

[root@localhost shell.sh]# ./test.exp 192.168.1.106 root jiajie
spawn ssh -l root 192.168.1.106
root@192.168.1.106's password:
Last login: Sat Sep  9 03:47:48 2017 from web
[root@localhost ~]# useradd jj
[root@localhost ~]# echo jiajie|passwd --stdin jj
Changing password for user jj.
passwd: all authentication tokens updated successfully.
[root@localhost ~]# exit
logout
Connection to 192.168.1.106 closed.
useradd jj is successfully.
Jobs has finished,Goodbye.

send "exit\r":登录出当前环境。

expect eof：结束expect匹配。

exit -onexit{...}：打印结束的提示信息。

五. shell脚本调用expect(1)

[root@localhost shell.sh]# vim test.sh
#!/bin/bash
ip=$1
user=$2
password=$3
expect <<EOF
set timeout 10
spawn ssh -l $user $ip
expect {
"yes/no" { send "yes\n";exp_continue }
"password" { send "$password\n" }
}
expect "]#" { send "useradd jj\n" }
expect "]#" { send "echo jiajie|passwd --stdin jj\n" }
expect "]#" { send "exit\n" }
expect eof
EOF

执行后的输出结果：

[root@localhost shell.sh]# ./test.sh 192.168.1.106 root jiajie
spawn ssh -l root 192.168.1.106
root@192.168.1.106's password:
Last login: Sat Sep  9 04:10:46 2017 from web
[root@localhost ~]# useradd jj
[root@localhost ~]# echo jiajie|passwd --stdin jj
Changing password for user jj.
passwd: all authentication tokens updated successfully.
[root@localhost ~]# exit
logout
Connection to 192.168.1.106 closed.
[root@localhost shell.sh]#

五. shell脚本调用expect(2)

通过shell脚本通过调用expect脚本实现批量认证:

expect脚本：

[root@localhost shell.sh]# vim scp.exp
#!/usr/bin/expect
if {$argc!=3} {
        send_user "Usage:expect need three arguments lisk thks:file host dir\n"
        exit 1
}
set srcname [lindex $argv 0]
set hostname [lindex $argv 1]
set destname [lindex $argv 2]
set password "jiajie"
spawn scp $srcname root@$hostname:$destname
set timeout 30
expect {
#        -timeout 2
        "yes/no" {send "yes\r";exp_continue}
        "*password:" {send "$password\r"}
#        timeout {puts "expect connect failure,please contact admin.";return}
}
expect eof
exit -onexit {
        send_user "Jobs has finished,Goodbye.\n"
}

shell脚本：

[root@localhost shell.sh]# vim scp.sh 
#!/bin/bash
if [[ "$#" != "2" ]];then
        echo "Usage:$0 src_filename des_filename"
        exit 0
fi
IP_LIST=(
        192.168.1.106
        192.168.1.170
        192.168.1.10
)
. /etc/init.d/functions
for ip in ${IP_LIST[*]}
do
        expect scp.exp $1 $ip $2 &> /dev/null
        if [ $? -eq 0 ];then
                action "$ip" /bin/true
        else
                action "$ip" /bin/false
        fi
done

scp.sh脚本通过调用expect脚本来实现分发功能。执行结果如下：

[root@localhost shell.sh]# sh  scp.sh  /etc/fstab /tmp/
192.168.1.106                                              [  OK  ]
192.168.1.170                                              [  OK  ]
192.168.1.10                                               [FAILED]

因为并没有192.168.1.10所有报错。