PyDaemonize - A python function to daemonize a python application

PyDaemonize

#!/usr/bin/env python

# PyDaemonize is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.

# PyDaemonize is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with PyDaemonize.  If not, see <http://www.gnu.org/licenses/>.

import os

def daemonize(log_folder, wd="/", umask=0):
    try:
        f = os.fork()
    except OSError as e:
        print("SEVERE: Error forking.. <{fork}>".format(fork=e))
        print("SEVERE: Trace -> {trace}".format(
            trace=traceback.format_exc()))
        raise e from None

    if f != 0:
        sys.exit(0)
    else:
        signal.signal(signal.SIGHUP, lambda x, y: print("SIGHUP received during process forking, ignoring signal"))
        os.chdir(wd)
        os.setsid()
        os.umask(umask)
        try:
            f = os.fork()
        except OSError as e:
            print("SEVERE: Error forking.. <{fork}>".format(fork=e))
            print("SEVERE: Trace -> {trace}".format(
                trace=traceback.format_exc()))
            raise e from None

        if f != 0:
            sys.exit(0)

        print("INFO: Started as Daemon")
        r = open("/dev/null", "r")
        os.dup2(r.fileno(), 0)
        buffering = 1  # line buffering
        w = open(log_folder, "w", buffering=buffering)
        os.dup2(w.fileno(), 1)
        os.dup2(w.fileno(), 2)