【linux】守护进程

应用实例：SSH、Telnet、FTP等系统服务

#include <stdio.h>#include <stdlib.h>#include <fcntl.h>int daemon(void){pid_t a;if ((a = fork())<0) {perror("fork!\n");exit(1);}if (a > 0) {exit(0);}setsid();//创建新回话，独立子进程if (chdir("/") < 0) {perror("chdir\n");exit(1);}umask(0);close(0);close(1);close(2);return 0;}int main(void){daemon();while(1) {FILE *fp = fopen("/root/work/test/daemon.log", "a+");fputs("daemon is running.\n", fp);fclose(fp);sleep(10);}}