Wait for non-child process to exit

Works on Unix like system only:

#!/usr/bin/python2.6
import sys,os,time
def is_running(pid):
    f='/proc/'+pid+'/status'
    if os.path.isfile(f):
        return True
    return False

while(is_running(sys.argv[1])):
    time.sleep(0.1)

Usage: ./wpid pid