linux中守护进程的启动

import sys
import time
import os

def daemonize():
    try:
        pid = os.fork()
        if pid > 0:
            # 退出父进程
            sys.exit(0)
    except OSError as e:
        sys.stderr.write(f"Fork #1 failed: {e.errno} ({e.strerror})\n")
        sys.exit(1)

    # 从父进程环境脱离
    os.chdir("/")
    os.setsid()
    os.umask(0)

    try:
        pid = os.fork()
        if pid > 0:
            # 退出第一个子进程
            sys.exit(0)
    except OSError as e:
        sys.stderr.write(f"Fork #2 failed: {e.errname} ({e.strerror})\n")
        sys.exit(1)

    # 重定向标准文件描述符
    sys.stdout.flush()
    sys.stderr.flush()
    si = open(os.devnull, 'r')
    so = open(os.devnull, 'a+')
    se = open(os.devnull, 'a+')

    os.dup2(si.fileno(), sys.stdin.fileno())
    os.dup2(so.fileno(), sys.stdout.fileno())
    os.dup2(se.fileno(), sys.stderr.fileno())

def main():
    while True:
        # 守护进程的主要逻辑
        print("Daemon is running...")
        time.sleep(5)

if __name__ == "__main__":
    daemonize()
    main()