CODE EXAMPLE FOR PHP

prestashop category as homepage

/* 
 * Better way with overide
 * 1. Create file override/controllers/front/IndexController.php
 * 2. Insert code
 * 3. Remove file cache/class_index.php
 */
class IndexControllerCore extends FrontController {
  public function initContent() {
  	Tools::redirect('index.php?id_category=3&controller=category');
  }
}