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

#include <pthread.h>

pthread_mutex_t mutex =  PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;

int main(int argc, char *argv[])
{
        struct timespec ts;

        ts.tv_sec = 5 + time(NULL);
        ts.tv_nsec = 0;
        pthread_mutex_lock(&mutex);
        system("date '+%H:%M:%S'");
        pthread_cond_timedwait(&cond, &mutex, &ts);
        system("date '+%H:%M:%S'");
        pthread_mutex_unlock(&mutex);

        clock_gettime(CLOCK_REALTIME, &ts);
        ts.tv_sec += 5;
        pthread_mutex_lock(&mutex);
        system("date '+%H:%M:%S'");
        pthread_cond_timedwait(&cond, &mutex, &ts);
        system("date '+%H:%M:%S'");
        pthread_mutex_unlock(&mutex);

        return 0;
}