HelloC/fork.c

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

#define LOOPS_PER_CHILD 2000
#define CHILDS 30

int main() {
    for (int start = 0; start < LOOPS_PER_CHILD * CHILDS; start += LOOPS_PER_CHILD) {
        pid_t pid = fork();
        if (pid == -1) {
            fprintf(stderr, "Error forking: %s\n", strerror(errno));
            return 1;
        } else if (pid == 0) {
            // I AM FORK!
            pid_t childPid = getpid();

            for (int i = start; i < start + LOOPS_PER_CHILD; i++) {
                fprintf(stdout, "%d: %d\n", childPid, i);
                fflush(stdout);
            }
            printf("Fork %d finished counting from %d\n", childPid, start);
            return 0;
        } else {
            printf("Fork %d successfull\n", pid);
        }
    }

    // wait for all childs to terminate
    while (wait(NULL) > -1);

    return 0;

    fork();
    fork();
    fork();
    printf("Hello World\n");
}