progsys1b

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/wait.h>

int main(){
    int statut;
    int pid[3];
    pid[0] = fork();
    if(pid[0] > 0){
        pid[1] = fork();
        if(pid[1] > 0){
            waitpid(pid[0], &statut, 0);
            waitpid(pid[1], &statut, 0);
            printf("Processus 1 : PID %d - PPID %d\n", getpid(), getppid());
        }
        else if(pid[1] == 0){ //P3
            printf("Processus 3 : PID %d - PPID %d\n", getpid(), getppid());
        }
        else{
            perror("Erreur de fork"); exit(errno);
        }
    }
    else if(pid[0] == 0){ //P2
        pid[2] = fork();
        if(pid[2] > 0){
            printf("Processus 2 : PID %d - PPID %d\n", getpid(), getppid());
        }
        else if(pid[2] == 0){
            sleep(1);
            printf("Processus 4 : PID %d - PPID %d\n", getpid(), getppid());
        }
        else{
            perror("Erreur de fork"); exit(errno);
        }
    }
    else{
        perror("Erreur de fork"); exit(errno);
    }
}