Cannot SSH into multiple servers with this script

zaibrockstar · 05-14-2014, 01:41 PM

Hi,

I am trying to get few parameters from all the servers I have specified in a file.

I have tried to write a script. But It doesn't go to all the servers. I have public private keys on all the servers already set. I don't want to install any other program for doing it.

Can any one suggest me why its not working. It prints the server names in the list but its not logging to the server for getting the parameters. It just prints the parameters from the server where the script is running.

Quote:

#! /bin/bash

FILE1="/export/home/servers.list"

Count=1
for Server in $( cat $FILE1 ); do

ssh -t $Server
KR=`rpm -qa | grep kernel`
LR=`last reboot`
UT=`uptime`
OS=`cat /etc/redhat-release`
Version=`uname -i `

echo $Server
echo -e "$OS \t BIT:$Version"
echo "Uptime:$UT"
echo "Last Reboot :$LR"
echo -e "$KR"
echo "---------------------"
((Count++))
done
Count=$((Count-1))
echo "^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^"
echo "Total number of Servers in file: $Count"
echo "^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^"

dwhitney67 · 05-14-2014, 01:49 PM

I'm not a Bash scripting expert, but it would appear that once you SSH to the remote server, you are expecting the commands that follow (e.g. `rpm -qa | grep kernel`) to execute on that remote server. Well, that's not going to happen.

All you are going to do with your script is connect (via SSH) to the remote server, and then it will sit there until you log out. Then your commands will be execute, but on the local system.

If you want to execute a command on the remote server, try something like:

Code:

KR=$(ssh $server "rpm -qa | grep kernel")
LR=$(ssh $server "last reboot")
...

ndc85430 · 05-14-2014, 01:54 PM

Another option would be to use Expect.

suicidaleggroll · 05-14-2014, 01:56 PM

It's not working because you can't use ssh like that. As far as your script is concerned, ssh is one program. Your script won't move to the next line until the ssh program finishes. Which means, your 'KR=`rpm -qa | grep kernel`' line will not run until after you've both logged into AND exited from the server in question and the ssh program exits.

If you want to run those commands on the server through ssh, then you need to put them IN the ssh call.

szboardstretcher · 05-14-2014, 02:13 PM

Something like this would work:

Code:

KR=`ssh -t $Server "rpm -qa | grep kernel"`
LR=`ssh -t $Server "last reboot"`
UT=`ssh -t $Server "uptime"`
OS=`ssh -t $Server "cat /etc/redhat-release"`
Version=`ssh -t $Server "uname -i"`

zaibrockstar · 05-14-2014, 03:48 PM

Quote:

Originally Posted by szboardstretcher

Something like this would work:

Code:

KR=`ssh -t $Server "rpm -qa | grep kernel"`
LR=`ssh -t $Server "last reboot"`
UT=`ssh -t $Server "uptime"`
OS=`ssh -t $Server "cat /etc/redhat-release"`
Version=`ssh -t $Server "uname -i"`

This works. Now I get Connection to server closed for every parameter. So I tried to get all parameters in a single session. Can you suggest ?

Code:

OS=`ssh -t $Server "cat /etc/redhat-release" Version="uname -i"`

Code:

OS=`ssh -t $Server "cat /etc/redhat-release";Version="uname -i"`

Code:

OS=`ssh -t $Server "cat /etc/redhat-release;Version="uname -i""`

All This throws error to me

Quote:

bash: -i: command not found

suicidaleggroll · 05-14-2014, 04:07 PM

What do you expect this:

Code:

OS=`ssh -t $Server "cat /etc/redhat-release";Version="uname -i"`

(or either of the other two variants you have) to do?

I think you should read some intro to bash scripting books to learn the basics of bash variables and storing the output of commands. You can't populate two variables from the output of a single command (which is what it appears you're trying to do here).