How to check if a process is still running using Python on Linux?

on linux, you can look in the directory /proc/$PID to get information about that process. In fact, if the directory exists, the process is running.

Mark's answer is the way to go, after all, that's why the /proc file system is there. For something a little more copy/pasteable:

 >>> import os.path
 >>> os.path.exists("/proc/0")
 False
 >>> os.path.exists("/proc/12")
 True