#include <stdio.h>
#include <sys/types.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>

int main ()
{
	int pid;
	int i;

	pid = fork ();
	if (pid) {  /* Parent */
		sleep (10);
		printf ("Killing Children (SIGTERM)\n");
		if (kill (-pid, SIGTERM) < 0)
			perror ("kill (SIGTERM)");
		printf ("Done\n");
		sleep (5);
		printf ("Killing Children (SIGKILL)\n");
		if (kill (-pid, SIGKILL) < 0)
			perror ("kill (SIGKILL)");
		printf ("Done\n");
		exit (0);
	} 
	else {  /* Child */
		if (setpgrp () < 0) {
			perror ("setpgrp");
			kill (getppid (), SIGTERM);
			exit (1);
		}
		printf ("Process Group created\n");
		for (i=0; i<2; ++i) {
			int pid2;
			pid2 = fork();
			if (pid2<0) perror ("fork()"), exit(2);
			/* Grandchilds */
			if (pid2 == 0) {
				printf ("Hi: My PID is %d\n", (int)getpid ());
				sleep (100);
				printf ("Terminating normally: %d %d\n",
					(int)getpid (), (int)getppid ());
				exit(0);
			}
		}
		exit(0);
	}
	return 0;
}