TYPO3 page not found sample

        /**
         * check, if user is logged in and if
         * page exist and set the right jump-page-uid
         */
        if(!isset($this->page->rootLine[0]) || count($this->page->rootLine[0]) == 0 || $this->isPageHidden()) {
            // requested page doesn't exist
            $redirectId = $this->noPageFoundId;
        }elseif(!(is_array($GLOBALS['TSFE']->fe_user->user) && isset($GLOBALS['TSFE']->fe_user->user['usergroup']) && count($GLOBALS['TSFE']->fe_user->user['usergroup']) > 0)){
            // requested page exists, but user is not logged in
            $redirectId = $this->loginId;
        } else {
            // user is logged in, requested page exist
            $redirectId = $this->accessDeniedId;
        }

        $url = $_SERVER['SCRIPT_NAME'].'?id='.$redirectId;

        $redirectUrl = $this->getRedirectFromRequestUri();
        $appendChar = $this->getAppendChar($url);

        if($redirectId != $this->noPageFoundId
        && $redirectUrl != $redirectId
        && $redirectUrl != '/'
        && $redirectUrl != ''){
                $url .= $appendChar . $this->redirectUrlParam . '=' . urlencode($redirectUrl);
        }

        // relocate to new url
        header('location:'.$url);