linux 精灵函数

void daemon()
{
int pid, fd;
if ((pid = fork()) == -1) exit(1);
if (pid != 0) exit(0);
if (setsid() == -1) exit(1);
if ((pid = fork()) == -1) exit(1);
if (pid != 0) exit(0);
//for (int i = 0; i < NOFILE; i++)
//	close(i);
/*
int fdtablesize = getdtablesize();
for (fd = 3; fd < fdtablesize; fd++)
{
close(fd);
}
*/
//if (chdir("/") == -1) exit(1);
//if ((fd = open("/dev/null", O_RDWR)) == -1) exit(1);
//dup2(fd, STDIN_FILENO);
//dup2(fd, STDOUT_FILENO);
//dup2(fd, STDERR_FILENO);
//close(fd);
if (umask(0) == -1) exit(1);
if (signal(SIGCHLD, SIG_IGN) == SIG_ERR) exit(1);
return ;
}