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

A *nix-only approach would be to shell-out to ps and check if a \n (new line) delimiter exists in the returned string.

Example IRB Output

1.9.3p448 :067 > `ps -p 56718`                                                          
"  PID TTY           TIME CMD\n56718 ttys007    0:03.38 zeus slave: default_bundle   \n"

Packaged as a Method

def process?(pid)  
  !!`ps -p #{pid.to_i}`["\n"]
end