Expect script to open an ssh connection and execute comand does not work.

Issues related to configuring your network
Post Reply
jstechg
Posts: 1
Joined: 2018/07/26 20:37:49

Expect script to open an ssh connection and execute comand does not work.

Post by jstechg » 2018/07/26 20:39:33

I need to connect from a machine with Centos 7 to a switch using ssh and in the same execute the command "sh vlan 110"

I have tried it in several ways:

1) I have written a script to expect with which I connect to the switch automatically and then manually enter the indicated command:

ssh_script.sh :

#!/usr/bin/expect
spawn ssh user@129.10.10.50
expect "assword:"
send "key_pass\r"
interact


After the connection is established with this expect script, I type the "sh vlan 110" command and it works fine.



2) Next, I added a pair of lines to the previous script in order to automatically execute the sh command on the switch:

ssh_script_v2.sh :

#!/usr/bin/expect
spawn ssh user@129.10.10.50
expect "assword:"
send "key_pass\r"
expect "prompt>"
sleep 5
send -- "sh vlan 110\r"

This new version of the script connects successfully to the switch, but when after five seconds it writes the command "sh vlan 100" it does not show itself nor does it appear any screen output and the connection is closed by ssh to the switch, as if we had written "exit", but without having written anything.


In order to show debug information I have executed this script with the command:

expect -d ssh_script_v2.sh

I get the output I show at the end of this message.


3) I directly execute the following command from the linux prompt:

ssh user@129.10.10.50 '( sh vlan 110 )' > file

I manually enter the password that ssh requests when establishing the connection and the following error is shown:
imish: invalid option -'c'
Try `imish -“help' for more information.

I comment this in case it provides some additional information, but what I want is that the expect script works properly.



EXECUTING ssh_script_v2.sh WITH expect -d:

expect version 5.45
argv[0] = expect argv[1] = -d argv[2] = ./ssh_script_v2.sh
set argc 0
set argv0 "./ssh_script_v2.sh"
set argv ""
executing commands from command file ./ssh_script_v2.sh
spawn ssh user@192.10.10.50
parent: waiting for sync byte
parent: telling child to go ahead
parent: now unsynchronized from child
spawn: returns {13051}

expect: does "" (spawn_id exp6) match glob pattern "assword:"? no
user@129.10.10.50's password:
expect: does "user@129.10.10.5o's password: " (spawn_id exp6) match glob pattern "assword:"? yes
expect: set expect_out(0,string) "assword:"
expect: set expect_out(spawn_id) "exp6"
expect: set expect_out(buffer) "user@129.10.10.50's password:"
send: sending "key_pass\r" to { exp6 }

expect: does " " (spawn_id exp6) match glob pattern "prompt>"? no


expect: does " \r\n" (spawn_id exp6) match glob pattern "prompt>"? no


OS version 6.1.1 IPIRouter 06/22/18 17:09:06
BOBCAT>
expect: does " \r\n\r\r\nOS version 6.1.1 IPIRouter 06/22/18 17:09:06\r\nprompt>" (spawn_id exp6) match glob pattern "prompt>"? yes
expect: set expect_out(0,string) "prompt>"
expect: set expect_out(spawn_id) "exp6"
expect: set expect_out(buffer) " \r\n\r\r\nOS version 6.1.1 IPIRouter 06/22/18 17:09:06\r\nprompt>"
send: sending "sh vlan 110" to { exp6 }

aks
Posts: 2558
Joined: 2014/09/20 11:22:14

Re: Expect script to open an ssh connection and execute comand does not work.

Post by aks » 2018/08/27 17:39:00

expect: does "user@129.10.10.5o's password: " (spawn_id exp6) match glob pattern "assword:"? yes
expect: set expect_out(0,string) "assword:"
expect: set expect_out(spawn_id) "exp6"
expect: set expect_out(buffer) "user@129.10.10.50's password:"
send: sending "key_pass\r" to { exp6 }

expect: does " " (spawn_id exp6) match glob pattern "prompt>"? no
The ssh is failing - that's where you should be looking at. Could be that key_pass doesn't match (may crlf etc.). There is no answer here as expect is very specific and is usually not the "real" answer to whatever the question is.

Also look into se issues ( well at a complete guess).

Post Reply