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

int sec;
void sigroutine(int signo) {
   switch (signo) {
   case SIGALRM:
   printf("Catch a signal -- SIGALRM ");
   break;
   case SIGVTALRM:
   printf("Catch a signal -- SIGVTALRM ");
   break;
   }
   return;
}

int main()
{
   struct itimerval value,ovalue,value2;
   sec = 5;
   printf("process id is %d ",getpid());
   signal(SIGALRM, sigroutine);
   signal(SIGVTALRM, sigroutine);
 
   value.it_value.tv_sec = 1;
   value.it_value.tv_usec = 0;
   value.it_interval.tv_sec = 1;
   value.it_interval.tv_usec = 0;
   setitimer(ITIMER_REAL, &value, &ovalue);

   value2.it_value.tv_sec = 0;
   value2.it_value.tv_usec = 500000;
   value2.it_interval.tv_sec = 0;
   value2.it_interval.tv_usec = 500000;
   setitimer(ITIMER_VIRTUAL, &value2, &ovalue);
   for (;;) ;
}