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

time_t curtime;

int main(int argc, char *args[]) {

  int seconds;
  void sigcatch();

  if (argc != 2) {
    fprintf(stderr, "usage: %s num-sec\n", args[0]);
    exit(1);
  }
  seconds = atoi(args[1]);

  time(&curtime);

  printf("Started the timer:\n%s", ctime(&curtime));
  alarm(seconds);
  signal(SIGALRM,sigcatch);

  while(1); // busy waiting
}

void sigcatch()  {
  time(&curtime);
  printf("Caught alarm at:\n%s",ctime(&curtime));
  exit(1); 
}