How can I check from Ruby whether a process with a certain pid is running?

Question

If there is more than one way, please list them. I only know of one, but I\'m wondering if there is a cleaner, in-Ruby way.

Answer 1

I've dealt with this problem before and yesterday I compiled it into the "process_exists" gem.

It sends the null signal (0) to the process with the given pid to check if it exists. It works even if the current user does not have permissions to send the signal to the receiving process.

Usage:

require 'process_exists'

pid = 12
pid_exists = Process.exists?(pid)