expect實現自動交互由淺入深

作為運維人員可以通過Shell可以實現簡單的控制流功能，如：循環、判斷等。但是對於需要交互的場合則必須通過人工來干預，有時候我們可能會需要實現和交互程序如telnet服務器等進行交互的功能。而Expect就使用來實現這種功能的工具。Expect是一個免費的編程工具語言，用來實現自動和交互式任務進行通信，而無需人的干預。

安裝expect,直接yum install expect -y

expect中相關命令

命令	解釋
spawn	啟動新的進程
send	用於向進程發送字符串
expect	從進程接收字符串
interact	允許用戶交互
exp_continue	匹配多個字符串在執行動作后加此命令

一般步驟：

啟動expect進程（spawn）--> 接收進程字符串(expect) --> 匹配字符串，成功發送字符串(send)，否則等待 --> 結束

好了就直接步入主題吧，不扯那些沒用的。直接上實例：

一. 入門例子：實現自動登錄

[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

參數	解釋
#!/usr/bin/expect	說明使用的shell環境
set timeout 30	設置超時時間，單位為秒，-1為沒有限制
spawn ssh...	需要執行的命令,這里是ssh登陸命令
expect "(yes/no)?"	判斷上次輸出結果里是否包含(yes/no)?的字符串
send "yes\r"	執行交互動作，接軌上一個命令，如果上面的expect執行成功，則發送yes
interact	執行完成后保持交互狀態，把控制權交給控制台

執行該實例：./test.exp

如果報錯-bash: ./test.exp: Permission denied,給744權限即可。

二. 使用變量：

[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:設置變量，后面直接變量，通過“$變量名”來調用

三. 使用位置參數：

[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]：表示位置參數，從num=0開始

send_user: 打印當前提示，相當於shell里的echo.

四. 執行多個命令：

[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"
}

執行后的結果輸出：

[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":登錄出當前環境。

expect eof：結束expect匹配。

exit -onexit{...}：打印結束的提示信息。

五. shell腳本調用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

執行后的輸出結果：

[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腳本調用expect(2)

通過shell腳本通過調用expect腳本實現批量認證:

expect腳本：

[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腳本：

[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腳本通過調用expect腳本來實現分發功能。執行結果如下：

[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]

因為並沒有192.168.1.10所有報錯。