Programming

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

int main()
{
    int i;
    int nproc = 3;
    pid_t pid;

    for (i = 0;i < nproc;i++) {
        switch ((pid = fork())) {
            case -1:
                printf("fork() error\n");
                break;

            case 0:
                 switch ((pid = fork())) {
                     case -1:
                        printf("second fork() error\n");
                        exit(0);
                     case 0:
                        printf("Child nr. %d\n", i);
                        exit(0);
                     default:
                        waitpid(pid, NULL, 0);
                        exit(0);
                 }
                 exit(0);

            default:
                waitpid(pid, NULL, 0);
                break;
        }
    }

    return 0;
}