ITIMER with sigaction example

itimer_test.c

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

static volatile sig_atomic_t g_called;

void g(int sig)
{
  g_called += 1;
  printf("g called - %d times\n", g_called);
}

int main()
{
  struct sigaction act, oact;
  g_called = 0;

  sigemptyset(&act.sa_mask);
  act.sa_flags = 0;
  act.sa_handler = g;
  sigaction(SIGALRM, &act, &oact);

  struct itimerval tv;
  tv.it_value.tv_sec = 2; //time of first timer
  tv.it_value.tv_usec = 0; //time of first timer
  tv.it_interval.tv_sec = 2; //time of all timers but the first one
  tv.it_interval.tv_usec = 0; //time of all timers but the first one
  setitimer(ITIMER_REAL, &tv, NULL);

  sigset_t mask;
  sigprocmask(0, NULL, &mask);
  sigdelset(&mask, SIGALRM);

  while(1) {
    sigsuspend(&mask);
  }


  return 0;
}

Hey! Thanks for posting this, I was having a hard time struggling with understanding how setitimer worked and this helped a lot!!!