Linux下的定时器

#include <stdio.h>
#include <signal.h>
#include <sys/time.h>

int main(int argc, char *argv[])
{
        sigset_t block;
        struct itimerval itv;

        sigemptyset(&block);
        sigaddset(&block, SIGALRM);
        sigprocmask(SIG_BLOCK, &block, NULL);

        itv.it_interval.tv_sec = 2;
        itv.it_interval.tv_usec = 0;
        itv.it_value = itv.it_interval;
        setitimer(ITIMER_REAL, &itv, NULL);

        while (1) {
                printf("%d\n", time(NULL));
                sigwaitinfo(&block, NULL);
        }

        return 0;
}