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

void catch_alarm(int x)
{
  fprintf(stdout, "Checkpointing...\n");
  alarm(30);
}

void do_something(void)
{
  for (;;) {
  }
}

int main(int argc, char **argv)
{
  signal(SIGALRM, &catch_alarm);
  alarm(5);
  do_something();
  exit(0);
  return(0);
}