Mar 28, 2013

Getting hold of a remote PID through Paramiko

By means of this article, I would like to share with you a little trick so as to obtain the PID of a remote process run through Paramiko. That is, figure for a moment that you launch an application on a remote system by using Paramiko, and you would like to kill that process after a certain timeout.

To be able to do that, you will have to grab the PID of that process after running it, and if you do not want to use "grep" or other kind of filters like this, the shell provides a curious mechanism which consists in executing that process in a new shell and afterwards, reading the PID of that process which has just been run.

Let's see an example.

import paramiko

if __name__ == "__main__":
    ssh = paramiko.SSHClient()
    ssh.connect("ubuntu-server.local", username="javi", password="xxxxxx")
    _, stdout, _ = ssh.exec_command("echo $$ ; exec python")
    pid = stdout.readline()
    print "PID of the remote process: " + pid
    _, stdout, _ = ssh.exec_command("ps -eo pid,command | grep %s" % pid)
    print "Looking for the process:\n" +
    ssh.exec_command("kill -s SIGINT %s" % pid)

As you can see above, I am running on a remote server a straightforward script called with the following lines.

while True:

Before executing the script through exec (replaces the current process image with a new one), I have put the order "echo $$", and in this way, I will be able to dump the PID of that process. Finally, I am using that PID to search for that process by means of ps and kill it. Let's run the module.

$ python 
PID of the remote process: 6020

Looking for the process:
 6020 python
 6021 bash -c ps -eo pid,command | grep 6020 
 6023 grep 6020

1 comment:

  1. Hey Javier, tried this example. But does not show the process ID for python. See below.

    PID of the remote process: 17540

    Looking for the process:
    17563 bash -c ps -eo pid,command | grep 17540?
    17582 grep 17540