1, Here Document interaction free

1.1 overview and format

• Provides a list of commands to interactive programs using I/O redirection
• An alternative to standard input
• Syntax format

command <<sign
...
...
sign

1.2 precautions for use

• The tag can use any legal character
• The slogan at the end must be written in the top grid, and there must be no characters in front of it
• There must also be no characters (including spaces) after the tag at the end
• Spaces before and after the opening mark are omitted

1.3 example 1: accept input and print through read command

[root@localhost opt]# cat 00.sh 
#!/bin/bash
read -i <<EOF
Hello Word!
EOF
echo $i
[root@localhost opt]# chmod +x 00.sh 
[root@localhost opt]# ./00.sh 
Hello Word!

1.4 example 2: set password for user through passwd

[root@localhost opt]# cat 00.sh 
#!/bin/bash
passwd zhangsan <<EOF
123456
123456
EOF
[root@localhost opt]# ./00.sh 
Change user zhangsan Your password.
New password: invalid password: password is less than 8 characters
 Re enter the new password: passwd: All authentication tokens have been successfully updated.

1.5 turn off variable replacement function

[root@localhost opt]# cat 00.sh 
#!/bin/bash
cat <<'EOF'
$abc
EOF
[root@localhost opt]# ./00.sh 
$abc

ps: use single quotation marks to realize the function of closing variable replacement

1.6 multiline notes

[root@localhost opt]# cat 00.sh 
#!/bin/bash
: <<EOF
this is a test file
EOF
[root@localhost opt]# ./00.sh 
[root@localhost opt]# 

1.7 remove TAB characters before each line

[root@localhost opt]# cat 00.sh 
#!/bin/bash
cat <<-'EOF'
	this is a test file
EOF
[root@localhost opt]# ./00.sh 
this is a test file

ps: '-' indicates inhibiting the TAB effect at the beginning of the line

2, Expect no interaction

2.1 basic commands

• A tool based on tcl
• For automatic control and testing
• Solve interaction related problems in shell scripts

expect

• Judge whether the last output result contains the specified string. If so, it will be returned immediately. Otherwise, it will be returned after the timeout
• Only the output of processes started by spawn can be captured
• It is used to receive the output after the command is executed, and then match the expected string

send

• Send a string to the process to simulate user input
• This command cannot automatically enter and line feed. Generally, / r (enter) should be added

spawn

• Start the process and track the subsequent interaction information

Terminator

• Expect EOF: wait for execution to end
• interact: keep the interactive state after execution and hand over the control to the console

set

• Set the timeout time, and continue to execute subsequent instructions when it expires
• The unit is seconds
• timeout -1 means never timeout
• By default, the timeout is 10 seconds

exp_continue

• Allow expect to continue executing instructions downward

send_user

• Echo command, equivalent to echo

Accept parameters

• The Expect script can accept parameters passed from bash
• It can be obtained using [lindex $argv n]
• n starts from 0 and represents the first, second and third... Parameters respectively

2.2 Expect syntax

• Single branch grammar

expect "password:" {send "mypassword\r";}

• Multi branch pattern syntax

expect "aaa" {send "AAA\r"}
expect "bbb" {send "BBB\r"}
expect "ccc" {send "CCC\r"}

ps:Send command does not have the function of carriage return and line feed. Generally, it needs to add \ r or \ n

ps: as long as any one of aaa, bbb or ccc is matched, execute the corresponding send statement and exit the expect statement

expect {
"aaa" {send "AAA";exp_continue}
"bbb" {send "BBB";exp_continue}
"ccc" {send "CCC"}
}

ps:exp_continue Indicates to continue the following matching. If it matches aaa，End of execution send Continue to match downward after the statement bbb

2.3 Expect Execution mode
 
#!/usr/bin/expect
#overtime
set timeout 20
# Open log
log_file test.log
#display information
log_user 1
#Define variables
set hostname [lindex $argv 0]
set password [lindex $argv 1]
#Tracking instruction
spawn ssh root@${hostname}
#Capture tips
expect {
  "connecting(yes/no)"
  {send "yes\r";exp_continue}
  "*password:"
  {send "${password}\r";}
}
#Transfer of control
interact
2.4 Embedded execution
 
#/bin/bash
hostname=$1
password=$2
#expect embedding
/usr/bin/expect <<-EOF
spawn ssh root@${hostname}
#Capture tips
expect {
  "connecting(yes/no)"
  {send "yes\r";exp_continue}
  "*password:"
  {send "${password}\r";}
}
expect "*]#"
{send "exit\r"}
expect eof
EOF
III Expect case
 

   

• Case 1: create user and set password

#!/bin/bash
user=$1
password=$2
useradd $user
expect <<EOF
spawn passwd $user
expect "New password:"
send "${password}\r"
expect "Retype new password:"
send "${password}\r"
expect eof;
EOF


    

• Case 2: use Expect to complete the SSH login process

#!/usr/bin/expect
set timeout 5
set hostname [lindex $argv 0]
set password [lindex $argv 1]
spawn ssh $hostname
expect {
  "Connection refused" exit
  "Name or service not known" exit
  "to continue" {send "yes\r";exp_continue}
  "password:" {send "$password\r"}
}
interact
exit


     

• Case 3: using Expect to complete the FTP login process

#!/bin/expect -f
set timeout 10
spawn ftp 192.168.10.10
expect "Name"
send "ftp\r"
expect "Password:*"
send "\r"
expect "ftp>*"
interact
expect eof