daemon.py 文件源码

def daemonize(self):
        """Deamonize class. UNIX double fork mechanism."""

        try:
            pid = os.fork()
            if pid > 0:
                # exit first parent
                sys.exit(0)
        except OSError as err:
            sys.stderr.write('fork #1 failed: {0}\n'.format(err))
            sys.exit(1)

        # decouple from parent environment
        os.chdir('/')
        os.setsid()
        os.umask(0)

        # do second fork
        try:
            pid = os.fork()
            if pid > 0:

                # exit from second parent
                sys.exit(0)
        except OSError as err:
            sys.stderr.write('fork #2 failed: {0}\n'.format(err))
            sys.exit(1)

        # redirect standard file descriptors
        sys.stdout.flush()
        sys.stderr.flush()
        stdi = open(os.devnull, 'r')
        stdo = open(os.devnull, 'a+')
        stde = open(os.devnull, 'a+')

        os.dup2(stdi.fileno(), sys.stdin.fileno())
        os.dup2(stdo.fileno(), sys.stdout.fileno())
        os.dup2(stde.fileno(), sys.stderr.fileno())

        # write pidfile
        self.write_pid()