def daemonize(self):
        try:
            pid = os.fork()
            if pid > 0:
                # Exit first parent
                sys.exit(0)
        except OSError, e:
            sys.stderr.write("fork #1 failed: %d (%s)\n" % (e.errno, e.strerror))
            sys.exit(1)

        # Decouple from parent environment
        os.chdir(self.home_dir)
        os.setsid()
        os.umask(self.umask)

        # Do second fork
        try:
            pid = os.fork()
            if pid > 0:
                # Exit from second parent
                sys.exit(0)
        except OSError, e:
            sys.stderr.write("fork #2 failed: %d (%s)\n" % (e.errno, e.strerror))
            sys.exit(1)

        if sys.platform != 'darwin':  # This block breaks on OS X
            # Redirect standard file descriptors
            sys.stdout.flush()
            sys.stderr.flush()
            si = file(self.stdin, 'r')
            so = file(self.stdout, 'a+')
            if self.stderr:
                se = file(self.stderr, 'a+', 0)
                os.dup2(se.fileno(), sys.stderr.fileno())
            else:
                se = sys.stderr
            os.dup2(si.fileno(), sys.stdin.fileno())
            os.dup2(so.fileno(), sys.stdout.fileno())

        def sigtermhandler(signum, frame):
            self.daemon_alive = False
        signal.signal(signal.SIGTERM, sigtermhandler)
        signal.signal(signal.SIGINT, sigtermhandler)

        if self.verbose >= 1:
            print "Started"

        # Write pidfile
        atexit.register(self.delpid)  # Make sure pid file is removed if we quit
        pid = str(os.getpid())
        file(self.pidfile, 'w+').write("%s\n" % pid)
Do the UNIX double-fork magic, see Stevens' "Advanced
dataset/ETHPy150Open oleiade/Elevator/debian/elevator/usr/lib/python2.6/dist-packages/elevator/utils/daemon.py/Daemon.daemonize