gistfile1.txt

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

int count = 0;
int pidMain;
int numThreads = 3;
int pids[3];

void sigquit()

{
	printf("%d finished work\n", getpid());
	exit(0);
}

void father(int SIG_NUM) 
{
	int i;
	count++;
	printf("father received signal, count = %d\n", count);
	if (count < 3)
		pause();
	if (count == 3)
		for (i = 0; i < numThreads; i++)
			kill(pids[i],SIGQUIT);
}

void son(int SIG_NUM) {
	printf("son %d received signal\n", getpid());
	sleep(1);
	if (kill(pidMain ,SIGUSR1) == -1) 
		perror("error sending signal to father\n");
	signal(SIGQUIT, sigquit);
	pause();
}



int main(int argc, char *argv[]) {
    int i; 
    pidMain = getpid();
    
    for (i = 0; i < numThreads; i++)
    {
        pids[i] = fork();
        
        switch (pids[i]) {
            case 0:
                i = numThreads;
                printf("Proc %d created\n", getpid());
                signal(SIGUSR2, son);
                pause();
                break;
                
            case -1:
                perror("Creating process failed\n");
                exit(EXIT_FAILURE);
                break;
            
            default: ;  
        }
    }
    
    if (getpid() == pidMain) {
        sleep(1);
        printf("Starting first cycle %d\n", getpid());
        
        signal(SIGUSR1, father);
        for (i = 0; i < numThreads; i++) {
			printf("pids[i] = %d started\n", pids[i]);
			kill(pids[i], SIGUSR2);
        }
        pause();
        printf("Finishing first cycle %d\n", getpid());

    }
    
    printf("pid %d finished work\n", getpid());
        
    return (EXIT_SUCCESS);
}