}
int main(int argc,char *argv[])
{
struct sigaction act;
int fd;
// 登记信号处理例程
act.sa_sigaction = handler;
sigemptyset(&act.sa_mask);
act.sa_flags = SA_SIGINFO;
sigaction(SIGRTMIN,&act,NULL);
// 需要了解当前目录"."的情况
fd = open(".", O_RDONLY);
fcntl(fd, F_SETSIG, SIGRTMIN);
fcntl(fd, F_NOTIFY, DN_MODIFY|DN_DELETE | DN_MULTISHOT);
/* we will now be notified if any of the files
in "." is modified or new files are created */