manager.py 文件源码

def daemonize(self, user=0, group=0):
        # do the UNIX double-fork magic, see Stevens' "Advanced
        # Programming in the UNIX Environment" for details (ISBN 0201563177)
        try:
            pid = os.fork()
            if pid > 0:
                # exit first parent
                sys.exit(0)
        except OSError as e:
            sys.stderr.write("Fork failed (#1): %d (%s)\n" % (e.errno, e.strerror))
            sys.exit(1)

        # decouple from parent environment
        # chdir -> don't prevent unmounting...
        os.chdir("/")

        # Create new process group with the process as leader
        os.setsid()

        # Set user/group depending on params
        if group:
            os.setregid(getgrnam(group)[2], getgrnam(group)[2])
        if user:
            os.setreuid(getpwnam(user)[2], getpwnam(user)[2])

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

        sys.stdout.flush()
        sys.stderr.flush()

        si = os.open("/dev/null", os.O_RDONLY)
        so = os.open("/dev/null", os.O_WRONLY)
        os.dup2(si, 0)
        os.dup2(so, 1)
        os.dup2(so, 2)
        os.close(si)
        os.close(so)

        self.logger.debug("Daemonized with PID %d.", os.getpid())