The ps command, which stands for process status, is a great way to find different processes running on a machine. Information like their pid (process id) is included. If you are tracking down a process to kill and find that that process is an unkillable zombie, then you may need to simultaneously kill the process' parent as well.

So, you'll need the parent pid as well. You can get both the pid and the parent pid of a process by including the -f flag with ps.

You may also want to include the -e flag to make sure that information about other users' processes is included in the results.