p8.1.c

linux程序设计例程

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

/* Daemonize myself. */
int
daemon (int nochdir, int noclose)
{
  pid_t pid;

  pid = fork ();

  /* In case of fork is error. */
  if (pid < 0)
    {
      perror ("fork");
      return -1;
    }

  /* In case of this is parent process. */
  if (pid != 0)
    exit (0);

  /* Become session leader and get pid. */
  pid = setsid();

  if (pid < -1)
    {
      perror ("setsid");
      return -1;
    }

  /* Change directory to root. */
  if (! nochdir)
    chdir ("/");

  /* File descriptor close. */
  if (! noclose)
    {
      int fd;

      fd = open ("/dev/null", O_RDWR, 0);
      if (fd != -1)
	{
	  dup2 (fd, STDIN_FILENO);
	  dup2 (fd, STDOUT_FILENO);
	  dup2 (fd, STDERR_FILENO);
	  if (fd > 2)
	    close (fd);
	}
    }

  umask (0027);

  return 0;
}

int main(void)
{
	daemon(0,0);
	sleep(1000);
	
	return 0;
}