Get PID of n'th parent (linux only)

pnid.py

import os
"""
Get PID of n'th parent
This works in linux only
"""

def pnid(n=1, pid=os.getpid()):
    for i in range(n):
        try:
            procfile = open("/proc/%s/status" % pid)
        except IOError:
            return -1
        with procfile as f:
            for line in f:
                if line.startswith("PPid:"):
                    pid = line.split()[1]
                    break
            else:
                pid = 0
                break
    return int(pid)