test.c

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

void child(int n) {
    while (1)
    {
        sleep(1);
        printf("child %d!\n", n);
    }
}

void parent() {
    while (1)
    {
        sleep(1);
        printf("parent!\n");
    }
}

int main(int argc, char **argv)
{
    printf("--beginning of program\n");

    int i = 0;
    for (i = 0; i < 5; i++) {
        pid_t pid = fork();
        if (pid == 0)
        {
            child(i);
        }
        else if (pid > 0)
        {
            // parent
        }
        else
        {
            // fork failed
            printf("fork() failed!\n");
            return 1;
        }
    }
    parent();

    printf("--end of program--\n");

    return 0;
}