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

int main() {
   int stat;
   int sig;
   sigset_t set;
   sigemptyset(&set);
   printf("add signal SIGINT: %i\n", sigaddset(&set, SIGINT));
   printf("add signal SIGKILL: %i\n", sigaddset(&set, SIGKILL));
   printf("add signal SIGTERM: %i\n", sigaddset(&set, SIGTERM));
   sigprocmask(SIG_BLOCK, &set, NULL);
   printf("Waiting...\n");
   stat = sigwait(&set, &sig);
   printf("Wait complete: %i (%i)\n", sig, stat);
   printf("`sh /opt/stop.sh`: %i\n", system("sh /opt/stop.sh"));
   return 0;
}