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| /*********************************************************************************
| * Copyright: (C) 2025 LingYun IoT System Studio
| * All rights reserved.
| *
| * Filename: daemon.c
| * Description: This file daemon() implement example program
| *
| * Version: 1.0.0(10/28/2025)
| * Author: Guo Wenxue <guowenxue@gmail.com>
| * ChangeLog: 1, Release initial version on "10/28/2025 10:18:29 AM"
| *
| ********************************************************************************/
|
| #include <stdio.h>
| #include <stdlib.h>
| #include <unistd.h>
| #include <sys/stat.h>
| #include <sys/types.h>
| #include <fcntl.h>
|
| void my_daemon(void)
| {
| pid_t pid;
|
| /* 第一次 fork，让父进程退出 */
| pid = fork();
| if (pid < 0)
| exit(1);
| else if (pid > 0)
| exit(0); /* 父进程退出 */
|
| /* 创建新会话，脱离控制终端 */
| if (setsid() < 0)
| exit(1);
|
| /* 第二次 fork，防止重新获得终端 */
| pid = fork();
| if (pid < 0)
| exit(1);
| else if (pid > 0)
| exit(0);
|
| /* 修改工作目录为根目录 */
| chdir("/");
|
| /* 重设文件掩码 */
| umask(0);
|
| /* 关闭标准文件描述符 */
| close(STDIN_FILENO);
| close(STDOUT_FILENO);
| close(STDERR_FILENO);
| }
|
| int main(void)
| {
| my_daemon();
|
| /* 守护进程主循环 */
| while (1)
| {
| int fd = open("/tmp/daemon.log", O_WRONLY | O_CREAT | O_APPEND, 0644);
| if (fd >= 0)
| {
| dprintf(fd, "Daemon alive, PID=%d\n", getpid());
| close(fd);
| }
| sleep(5);
| }
|
| return 0;
| }
|
|
