shell script to ssh into another server and execute a script in that server

nithi28 · 02-12-2019, 12:47 AM

HI,
i have 6 servers in my testing env. I want to write a script to stop tomcat server in all boxes by logging into one box instead of logging into each and every box.
please help me with shell scripting, ssh and execute a script in all other boxes.

* SSH with password and custom port

berndbausch · 02-12-2019, 01:11 AM

I don’t know how to stop tomcat, but to execute a script on a remote server, I am aware of two options.

Option 1: Put the script in a file, copy the file to the remote system, then execute it remotely.

Code:

vi script.sh
for i in server{1..6}
do 
    scp script.sh ${i}:
    ssh $i sh script.sh
done

Option 2: If the script consists of few commands, you can execute it this way:

Code:

for i in server{1..6}
do 
    ssh $i sh -c “command1; command2; command3”
done

ondoho · 02-12-2019, 01:46 AM

Quote:

Originally Posted by nithi28

* SSH with password and custom port

i'm sure

Code:

man ssh

can answer that part?

Turbocapitalist · 02-12-2019, 01:54 AM

Quote:

Originally Posted by nithi28

* SSH with password and custom port

The custom port part is easy, but for the authentication you really need to be using SSH keys instead of passwords. SSH keys authentication is not only the established best practice, it is also the easiest way to trigger a remote script.

See the command="command" description in "man sshd" in the section "AUTHORIZED_KEYS FILE FORMAT"

1) write script
2) upload to remote servers
3) generate and install a key pair for each server
4) modify public key to trigger script
5) make a shortcut for each server in ~/.ssh/config

MadeInGermany · 02-12-2019, 10:17 PM

Quote:

Originally Posted by berndbausch

I don’t know how to stop tomcat, but to execute a script on a remote server, I am aware of two options.

Option 1: Put the script in a file, copy the file to the remote system, then execute it remotely.

Code:

vi script.sh
for i in server{1..6}
do 
    scp script.sh ${i}:
    ssh $i sh script.sh
done

Option 2: If the script consists of few commands, you can execute it this way:

Code:

for i in server{1..6}
do 
    ssh $i sh -c "command1; command2; command3"
done

Option 2 (BTW I changed the "quotes" to ASCII!) has the disadvantage that you have to consider local evaluation then remote evaluation.

Option 3: pass script via stdin

Code:

for i in server{1..6}
do 
    <scipt.sh ssh $i /bin/bash -s
done

There is no local evaluation. It even takes script arguments after the -s
The /bin/bash should match the #!/bin/bash shebang in the script; for example use /bin/ksh for a #!/bin/ksh script.

berndbausch · 02-13-2019, 12:07 AM

Quote:

Originally Posted by MadeInGermany

Option 2 (BTW I changed the "quotes" to ASCII!) has the disadvantage that you have to consider local evaluation then remote evaluation.

True. Though this may be a plus, depending on the task at hand.

I promise I will work on my quotes :P