#include <stdio.h>
#include <unistd.h>
#include <signal.h>

void byebye(int signum) {
  printf("Timed out.  Bye.\n");
  exit(0);
}

int main(void) {
  signal(SIGALRM, &byebye);
  printf("Hit <enter> to continue >> ");
  fflush(stdout);
  alarm(3);
  (void) getchar();
  printf("Received your <enter>.  Bye.\n");
  return 0;
}