int main()
{
    pid_t zaklad;
    if ((zaklad = fork()) >=0) //successful fork
    {
        if ((zaklad = fork()) ==0) //child process
        {
            printf("This is child process \n");
        }
        if ((zaklad = fork()) >0)
        {
            printf("This is parent process \n");
        }

    }
    else //fork failed
    {
        fprintf (stderr,"fork error\n");
    }

}