Shell script interaction free

Catalog

One 、Here Document No interaction

1、 Command format

2、Here Document Precautions for use

3、 example

Two 、Expect

1、 Basic commands

2、 example

---

One 、Here Document No interaction

1、 Command format

Use l/o Redirection provides a list of commands to interactive programs

A substitute for standard input

Command format

command << Mark

Content

Mark

2、Here Document Precautions for

（1） Tags can use any legal character

（2） The ending mark must be written in the top case , There can't be any characters in front of it .

（3） There can't be any characters after the tag at the end （ Including Spaces ）

（4） Spaces before and after the opening mark are omitted

3、 example

（1） The number of rows can be counted without interaction

[root@localhost ~]# wc -l <<EOF
> 1
> 456
> 7810
> EOF
3

（2） adopt read Command receive command

[root@localhost ~]# read b <<EOF
> like
> EOF
[root@localhost ~]# echo $b
like

 （3） No need to change password interactively

[root@localhost ~]# passwd zs <<EOF
> 123123
> 123123
> EOF
 Change user  zs  Password  .
 new   password ： Invalid password ：  The password is less than  8  Characters 
 Reenter the new   password ：passwd： All authentication tokens have been successfully updated .

（4）  When you write to a file, you first replace the variable with the actual value , combining cat Command complete output

#!/bin/bash
file="2.txt"
i=tea
cat> $file <<EOF
l like $i
EOF


[root@localhost ~]# cat 2.txt
l like tea

 

（5）  Turn off the function of variable replacement , Output the characters as they are , Without any modification or replacement

#!/bin/bash
var="thress year"
myvar=$(cat <<'EOF'
today is friday
qqche
$var
EOF
)
echo $myvar

 

Two 、Expect

1、 Basic commands

Based on the tcl A tool based on language , It is often used for automatic control and testing , solve shell Exchange related problems in scripts

Install package

[root@localhost ~]# yum install expect -y

（1） Script interpreter

expect The script first introduces the file , Indicate which one is used shell

[root@localhost ~]# which expect
/usr/bin/expect

（2）spawn

spawn Usually followed by a Linux Carry out orders , Open a conversation 、 Start the process , And track subsequent interaction information . example ：spawn passwd root

（3）expect

Judge whether the last output result contains the specified string , If so, return immediately , Otherwise, it will wait for the timeout to return

Can only be captured by spawn The output of the started process

Used to receive output after command execution , And then match the expected string

（4）send

Send string to process , The user simulates the user's input ; This command does not automatically enter to wrap lines , Generally, we need to add \r（ enter ） perhaps \n

（5）interact
Keep interactive after execution , Give control to the console

（6）set
Set timeout , If it expires, continue to execute subsequent instructions
The unit is seconds
timeout -l Means never time out
By default ,timeout yes 10 second

（7）exp_continue
allow expect Continue down the instruction
analysis ： If there is a statement error , No addition exp_continue, That's it , sign out
add exp_continue Will continue to execute subsequent statements , Do not exit .

（8）send_user
Echo command , amount to echo

（9） Receiving parameters
Expect Scripts can accept from bash Parameters passed
have access to [lindex $argv n] get
n from 0 Start , They are the first , the second , Third … Parameters
/bin/bash The location variable is from $1 Start to $9 end
Expect[lindex $argv 0] amount to /bin/bash Of $1

2、 example

Set up ssh Log in without interaction .

#!/usr/bin/expect
# ssh No interaction 
set timeout 60                       Set timeout 60 second 
set hostname [lindex $argv 0]        Set variable name , The value of the variable comes from the position variable 0
set password [lindex $argv 1]
log_file a.log                       Set the folder where log file records are saved 
log_user 1                           Record screen output 
spawn ssh root@$hostname             Initiate the startup process ssh A host name 
expect {
    "(yes/no)" {send "yes\r;exp_continue"}
    "password" {send "$password\r"}
}
interact