How do I run a local bash script on remote machines via ssh?

Question

I am looking for a way to push configuration from one central machine to several remote machines without the need to install anything on the remote machines.

The aim is to do something like you would find with tools like cfengine, but on a set of machines that don't have agents set up. This might actually be a good technique of setting up cfagent on a set of existing remote machines.

Thanks!

Answer 1

You can pass a script and have it execute ephemerally by piping it in and executing a shell.

e.g.

echo "ls -l; echo 'Hello World'" | ssh me@myserver /bin/bash

Naturally, the "ls -l; echo 'Hello World'" part could be replaced with a bash script stored in a file on the local machine.

e.g.

cat script.sh | ssh me@myserver /bin/bash

Cheers!

Answer 2

I would recommend python's Fabric for this purpose:

#!/usr/bin/python
# ~/fabfile.py

from fabric_api import *

env.hosts = ['host1', 'host2']
def deploy_script():
    put('your_script.sh', 'your_script.sh', mode=0755)
    sudo('./your_script.sh')

# from shell
$ fab deploy_script

You should be able to use the above to get started. Consult Fabric's excellent documentation to do the rest. As an addendum, it's totally possible to write your script wholly within Fabric -- no copying needed, however it should be noted that to change the script on all machines, you would only need to edit the local copy and redeploy. Furthermore, with a little more than basic usage of the API, you can modify the script based on which host it is currently running on and/or other variables. It's a sort of pythonic Expect.

Answer 3

Why not simply copy the script first, then running it?

scp your_script.sh the_server:
ssh the_server "chmod +x your_script.sh; ./your_script.sh"

Of course you should be careful not to upload it to a world-writable place, so nobody else could fiddle with it before you run it (possibly as root).