问'IOError：[Errno 9]在后台进程中调用子进程时文件描述符错误

EN

if args.daemon:
    pid = os.fork()
    if pid > 0:
        sys.exit(0)
    os.close(0)
    os.close(1)
    os.close(2)

 if args.daemon:
    stdin = '/dev/null'
    stdout = '/dev/null'
    stderr = '/dev/null'

    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("/")
    os.setsid()
    os.umask(0)

    # 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)

    # redirect standard file descriptors
    sys.stdout.flush()
    sys.stderr.flush()
    si = file(stdin, 'r')
    so = file(stdout, 'a+')
    se = file(stderr, 'a+', 0)
    os.dup2(si.fileno(), sys.stdin.fileno())
    os.dup2(so.fileno(), sys.stdout.fileno())
    os.dup2(se.fileno(), sys.stderr.fileno())