Expect commands in Linux

ExpectMediumShaoxing

expect is by Don Libes based on Tcl (Tool Command Language) Language developed, primarily for automated interactive operation scenarios, using expect to handle interactive commands, you can automate the process by writing interactive processes such as SSH logins, FTP logins, and so on in a single script. This is especially useful in environments where multiple servers are required to perform the same operation, which can greatly improve the productivity of system administrators.

expectCommandExpectSyntax:

expect [ options ] [- c Cmds] [[[-[f|b]] cmdfile] [args]

Options

-C: Executes the expect scriptfrom the command line , and the default expect is executed interactively

Example:

Expect-c ' expect ' \ n ' {send ' pressed enter\n '}

-D: Output debug information can be exported

Example:

Expect-d Ssh.exp

expect related commands in

Spawn: Start a new processSend: Used to send a string to a processExpect: Receive a string from a processInteract: Allow user interactionExp_continueMatch multiple strings add this command after performing an action

ExceptThe most common syntax(Tcllanguage:Mode-Action)Single branch mode syntax:

Expect "HI" {send "you said Hi\n"}

After matching to hi , it will output "you said hi"and wrap

Multi-branch mode syntax:

Expect "HI" {send "you said hi\n"} \

"hehe" {send "hehe yourself\n"} \

"Bye" {send "good bye\n"}

Match Hi,hello,bye any string, the corresponding output is executed. Equivalent to the following:

Expect {

"HI" {send "you said Hi\n"}

"hehe" {send "hehe yourself\n"}

"Bye" {send "good bye\n"}

}

Example

Cat Ssh1.exp

#!/usr/bin/expect

Spawn ssh 192.168.8.100

Expect {

"Yes/no" {send "yes\n"; Exp_continue}

"Password" {send "magedu\n"}

}

Interact

#expect EOF

Example:variables

Cat Ssh2.exp

#!/usr/bin/expect

Set IP 192.168.8.100

Set User root

Set Password magedu

Set Timeout 10

Spawn ssh [email protected] $ip

Expect {

"Yes/no" {send "yes\n"; Exp_continue}

"Password" {send "$password \ n"}

}

Interact

Example:Position Parameters

Vim Ssh3.exp

#!/usr/bin/expect

Set IP [lindex $argv 0]

Set user [lindex $argv 1]

Set password [lindex $argv 2]

Spawn ssh [email protected] $ip

Expect {

"Yes/no" {send "yes\n"; Exp_continue}

"Password" {send "$password \ n"}

}

Interact

#./ssh3.exp 192.168.8.100 rootmagedu

Example: executing multiple commands

Cat Ssh4.exp

#!/usr/bin/expect

Set IP [lindex $argv 0]

Set user [lindex $argv 1]

Set password [lindex $argv 2]

Set Timeout 10

Spawn ssh [email protected] $ip

Expect {

"Yes/no" {send "yes\n"; Exp_continue}

"Password" {send "$password \ n"}

}

Expect "]#" {send "Useradd haha\n"}

Expect "]#" {send "echo magedu |passwd--stdin haha\n"}

Send "exit\n"

Expect EOF

#./ssh4.exp 192.168.8.100 rootmagedu

Example:ShellScript callsexpect

Vim ssh5.sh

#!/bin/bash

Ip=$1

User=$2

Password=$3

Expect <<eof

Set Timeout 10

Spawn [email protected] $ip

Expect {

"Yes/no" {send "yes\n"; Exp_continue}

"Password" {send "$password \ n"}

}

Expect "]#" {send "useraddhehe\n"}

Expect "]#" {send "echomagedu|passwd--stdinhehe\n"}

Expect "]#" {send "exit\n"}

Expect EOF

Eof

#./ssh5.sh 192.168.8.100 Rootmagedus

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Expect commands in Linux