linux c 創建守護進程

 
#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <stdlib.h>

int init_daemon(void) {
 pid_t pid;
 int i;
 FILE *fp;
 time_t mytime;

 pid = fork();
 if (pid == -1) {
  return -1;
 } else if (pid > 0) {
  exit(0);
 }
 else {
  setsid();//創建新的會話空間

  chdir("/tmp");
  umask(0);
  for (i = 0; i < getdtablesize(); ++i)
   {
   close(i);
   }
  while (1) {
   sleep(2);
   if ((fp = fopen("test.log", "a")) != NULL)
   {
    mytime = time(0);
    fprintf(fp, "I'm here at %s \n", asctime(localtime(&mytime)));
    fclose(fp);
   }
  }


  return 0;
 }
}

int main(void) {

 init_daemon();
 return 0;

}