Automatic interaction to achieve the script via expect Linux tools

1 install expect Tool

expect to establish a suite automated interactive tcl basis, in some scenarios require interactive input commands, interactive communications may be provided by a script which automatically interaction process is:

spawn start the specified process -> expect to obtain the specified keyword -> send want to specify a process to send the specified command -> execution is complete, quit.

Because tcl expect is based, it is necessary to ensure that the system is installed tcl:

# Check whether the installation TCL: 
[root @ localhost ~] # whereis TCL 
TCL: /usr/lib64/tcl8.5 /usr/include/tcl.h /usr/share/tcl8.5 

# If not, use yum install tcl and expect: 
[the root @ localhost ~] # yum the install -Y tcl 
[the root @ localhost ~] # yum expect the install -Y 

# expect to see the path of the installation: 
[the root @ localhost ~] # Command expect -v 
/ usr / bin / expect

2 expect of commonly used commands

command	Explanation
spawn	Start a new interactive process, followed by a specified program or command
expect	Operation after receiving information from the process, if the match is successful, we expect the implementation of
send	Send string to the process
send exp_send	For transmitting the information specified string
exp_continue	In expect many times you need to use match
send_user	It corresponds to the printout of the shell echo
interact	Allow user interaction
exit	Exit expect script
eof	expect execution quits
set	Define the variable
puts	Output variables
set timeout	Set the timeout

3 action principle Introduction

3.1 Example scripts

Here ssh remote login script to a server as an example, assume that this script name is remote_login.sh:

#!/usr/bin/expect

set timeout 30
spawn ssh -l root 172.16.22.131
expect "password*"
send "123456\r"
interact

3.2 Interpretation scripting capabilities

(1) #!/usr/bin/expect

Above must be in the first line of the script file that tells the operating system, this script needs to use the system which script parsing engine to perform.

Specific path can be viewed through the command -v expect command.

note:

expect here and Linux bash, Windows and other programs, like the cmd, is a script execution engine.

Scripts need to be executable (chmod + x remote_login.sh, or chmod 755 auto_login.sh), then you can run the command ./remote_login.sh;

If you enter sh remote_login.sh, meaning is not the same: a clear call sh engine to execute this script, this time the first line of # / usr / bin / expect becomes ineffective!.

(2) set timeout 30

Connection timeout is 30 seconds.

(3) spawn ssh -l root 172.16.22.131

spawn, send commands are internal commands expect the tool, if the tool is not installed expect, "spawn not found" error occurs and so on.

Do not use which command to look like the spawn spawn, because there is no such program.

(4) expect "password*"

This command is used to determine the last string in the output contains "password *", if there is an immediate return, otherwise after waiting for some time to return. While waiting here a long timeout is set previously, that is, 30 seconds.

(5) send "123456\r"

Here is the implementation of the interactive action, and is equivalent to manually enter the password.

Tip: Command the end of the string with \ r, so, if the abnormal state of waiting appeared to be able to stay down for further verification.

(6) interact

keep users expect to perform after the completion of the cross-state, this time the user can manually operate.

If not this one, expect to perform after the completion of the script will exit just past Telnet terminal, the user would be unable to continue to operate.

Other examples of the use of scripts 4

4.1 Direct execute multiple commands expect

Note that the first line of content, it can only be performed by such a script ./script.sh this case:

! # / usr / bin / -f Expect 

SET timeout 10 
# switch to root, and then the ls command df: 
the spawn SU - root 
Expect "Password *" 
send "123456 \ R & lt" 
Expect "] *" # wildcard 
send " LS \ r " 
expect" # * "# wildcard another form of 
the send" df -Th \ r " 
the send" exit \ r "# exit spawn open process 

expect eof # expect to exit this interactive program

4.2 execute multiple commands by calling expect shell

Note that the first line of content, in this case by sh script.sh, bash script.sh or ./script.sh, can execute such a script:

#!/bin/bash

ip="172.16.22.131"
username="root"
password="123456"

# 指定执行引擎
/usr/bin/expect <<EOF
    set time 30
    spawn ssh $username@$ip df -Th
    expect {
        "*yes/no" { send "yes\r"; exp_continue }
        "*password:" { send "$password\r" }
    }
    expect eof
EOF

5 spawn not found solutions

This error occurs basically a scholar: Linux shell script in two ways:

One is the script as a command line parameter sh, as sh remote_login.sh, or sh /data/remote_login.sh;

One is the script as an executable script has execute permissions, such as ./remote_login.sh, or /data/remote_login.sh.

As sh command-line parameters to run, then the first line of the script #! / Usr / bin / expect will fail, it will spawn not found, send not found error, etc., all of the above script must automate_login.sh run the following command:

./automate_expect.sh