#!/usr/bin/env python
#
# based on http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/278731

import os, pwd, grp

def daemonize(euid = None, egid = None):
    """Detach a process from the controlling terminal,
    change euid/egid and run it in the background as a daemon.
    """
    try:
        pid = os.fork()
    except OSError, e:
        raise Exception, "%s [%d]" % (e.strerror, e.errno)
    if (pid == 0):
        os.setsid()
        try:
            pid = os.fork()
        except OSError, e:
            raise Exception, "%s [%d]" % (e.strerror, e.errno)
        if (pid == 0):
            os.chdir('/')
            os.umask(0)
        else:
            os._exit(0)
    else:
        os._exit(0)
    for fd in range(0, 2):
        os.close(fd)
    os.open(os.devnull, os.O_RDONLY) # fd0 stdin
    os.open(os.devnull, os.O_WRONLY) # fd1 sdtout
    os.dup2(1, 2) # fd2 stderr
    if euid:
        os.seteuid(pwd.getpwnam(euid)[2])
    if egid:
        os.setegid(grp.getgrnam(egid)[2])