Analysis of Expect Automation Interactive Application example
Expect is an automatic interaction suite, which is mainly used in the execution of commands and programs, the system is required to input a specified string in the form of interaction to achieve interactive communication.
Expect automatic interaction process:
Spawn starts the specified process-expect gets the specified keyword-send sends the specified character to the specified program-execute completion exit
Simple example 1:
Vim test.exp # # exp is the extension of expect script
#! / usr/bin/expect # # use the expect parser
Spawn ssh root@192.168.1.5 free # # execute ssh command with spawn execute free command after login
Expect "* password" # # matches the acquired string
Send "123456\ n" # # send the password to the system after matching.\ nIt's a newline.
Expect eof # # end of processing expect
Example 2:
#! / usr/bin/expect
Spawn ssh root@192.168.1.5 free
Expect {
"yes/no" {exp_send "yes\ r"; exp_continue}
"* password" {exp_send "123456\ r"}
}
Expect eof
Example 3:
#! / usr/bin/expect
Spawn test.sh
Expect {
"username" {exp_send "test\ r"; exp_continue}
"* password" {exp_send "123456\ r"; exp_continue}
"* mail*" {exp_send "lidao@163.com\ r"}
}
Expect eof
Summary of common commands in expect
The spawn interactive program starts with a command or a specified program
If the matching information is obtained by expect, the program action behind expect will be executed if the match is successful.
Send exp_send is used to send specified string information
Exp_continue needs to be used for multiple matches in expect.
Send_user is used to print out the equivalent of echo in shell.
Exit exits the expect script
Eof expect execution ends and exits
Set defines variables
Puts output variable
Set timeout sets the timeout
Example 4:
#! / usr/bin/expect
If {$argc! = 2} {
Puts "expect $argv0 ip command"
Exit
}
Set ip [lindex $argv 0]
Set cmd [lindex $argv 1]
Set password "123456"
Spawn ssh root@$ip $cmd
Expect {
"yes/no" {send "yes/r"; exp_continue}
"* password" {send "$password\ r"}
}
Expect eof
Expect test.exp 192.168.1.5 "free-m"
Instance 5:ssh key authentication
Generate secret key
Ssh-keygen-t dsa-P''- f ~ / .ssh/id_dsa > / dev/null 2 > & 1
Vim test.exp
#! / usr/bin/expect
If [$argc! = 2] {
Send_user "usage: expect test.exp file host\ n"
Exit
}
Set file [lindex $argv 0]
Set host [lindex $argv 1]
Set password "123456"
Spawn ssh-copy-id-I $file "- p 22 root@$host"
Expect {
"yes/no" {send "yes\ r"; exp_continue}
"* password" {send "$password\ r"}
}
Expect eof
Vim kk.sh Loop expect script
#! / bin/bash
For n in 2 3 4 5 6 7
Do
Expect test.exp ~ / .ssh/id_dsa.pub 192.168.1.roomn
Done
Expect is easy to operate, easy to use, easy to learn and use, but now it is not used much in work, and most of it is used to assist the execution of other program scripts.
