$_SERVER["DOCUMENT_ROOT"] = '/home/bitrix/www';
$DOCUMENT_ROOT = $_SERVER["DOCUMENT_ROOT"];

define("NO_KEEP_STATISTIC", true);
define("NOT_CHECK_PERMISSIONS",true);
define("BX_CRONTAB", true);
define('BX_NO_ACCELERATOR_RESET', true);

require($_SERVER["DOCUMENT_ROOT"]."/bitrix/modules/main/include/prolog_before.php");

@set_time_limit(0);
@ignore_user_abort(true);

CModule::IncludeModule("search")
$res = CSearch::ReIndexAll();

echo 'Проиндексировано элементов: ', $res;