[root@alarmpi ~]# crontab -u http -e
crontab: no changes made to crontab
[root@alarmpi ~]# cat /usr/share/webapps/owncloud/cron.php
<?php
/**
 * @author Bernhard Posselt <dev@bernhard-posselt.com>
 * @author Christopher Schäpers <kondou@ts.unde.re>
 * @author Jakob Sack <mail@jakobsack.de>
 * @author Joas Schilling <nickvergessen@owncloud.com>
 * @author Jörn Friedrich Dreyer <jfd@butonic.de>
 * @author Morris Jobke <hey@morrisjobke.de>
 * @author Oliver Kohl D.Sc. <oliver@kohl.bz>
 * @author Phil Davis <phil.davis@inf.org>
 * @author Robin Appelman <icewind@owncloud.com>
 * @author Steffen Lindner <mail@steffen-lindner.de>
 * @author Thomas Müller <thomas.mueller@tmit.eu>
 * @author Vincent Petry <pvince81@owncloud.com>
 *
 * @copyright Copyright (c) 2015, ownCloud, Inc.
 * @license AGPL-3.0
 *
 * This code is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License, version 3,
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 *
 */

try {

        require_once 'lib/base.php';

        if (\OCP\Util::needUpgrade()) {
                \OCP\Util::writeLog('cron', 'Update required, skipping cron', \OCP\Util::DEBUG);
                exit;
        }
        if (\OC::$server->getSystemConfig()->getValue('maintenance', false)) {
                \OCP\Util::writeLog('cron', 'We are in maintenance mode, skipping cron', \OCP\Util::DEBUG);
                exit;
        }

        if (\OC::$server->getSystemConfig()->getValue('singleuser', false)) {
                \OCP\Util::writeLog('cron', 'We are in admin only mode, skipping cron', \OCP\Util::DEBUG);
                exit;
        }

        // load all apps to get all api routes properly setup
        OC_App::loadApps();

        \OC::$server->getSession()->close();

        // initialize a dummy memory session
        $session = new \OC\Session\Memory('');
        $cryptoWrapper = \OC::$server->getSessionCryptoWrapper();
        $session = $cryptoWrapper->wrapSession($session);
        \OC::$server->setSession($session);

        $logger = \OC::$server->getLogger();

        // Don't do anything if ownCloud has not been installed
        if (!OC_Config::getValue('installed', false)) {
                exit(0);
        }

        \OC::$server->getTempManager()->cleanOld();

        // Exit if background jobs are disabled!
        $appMode = \OCP\BackgroundJob::getExecutionType();
        if ($appMode == 'none') {
                if (OC::$CLI) {
                        echo 'Background Jobs are disabled!' . PHP_EOL;
                } else {
                        OC_JSON::error(array('data' => array('message' => 'Background jobs disabled!')));
                }
                exit(1);
        }

        if (OC::$CLI) {
                // set to run indefinitely if needed
                set_time_limit(0);

                // the cron job must be executed with the right user
                if (!OC_Util::runningOnWindows())  {
                        if (!function_exists('posix_getuid')) {
                                echo "The posix extensions are required - see http://php.net/manual/en/book.posix.php" . PHP_EOL;
                                exit(0);
                        }
                        $user = posix_getpwuid(posix_getuid());
                        $configUser = posix_getpwuid(fileowner(OC::$SERVERROOT . '/config/config.php'));
                        if ($user['name'] !== $configUser['name']) {
                                echo "Console has to be executed with the same user as the web server is operated" . PHP_EOL;
                                echo "Current user: " . $user['name'] . PHP_EOL;
                                echo "Web server user: " . $configUser['name'] . PHP_EOL;
                                exit(0);
                        }
                }

                $config = OC::$server->getConfig();
                $instanceId = $config->getSystemValue('instanceid');
                $lockFileName = 'owncloud-server-' . $instanceId . '-cron.lock';
                $lockDirectory = $config->getSystemValue('cron.lockfile.location', sys_get_temp_dir());
                $lockDirectory = rtrim($lockDirectory, '\\/');
                $lockFile = $lockDirectory . '/' . $lockFileName;

                if (!file_exists($lockFile)) {
                        touch($lockFile);
                }

                // We call ownCloud from the CLI (aka cron)
                if ($appMode != 'cron') {
                        \OCP\BackgroundJob::setExecutionType('cron');
                }

                // open the file and try to lock it. If it is not locked, the background
                // job can be executed, otherwise another instance is already running
                $fp = fopen($lockFile, 'w');
                $isLocked = flock($fp, LOCK_EX|LOCK_NB, $wouldBlock);

                // check if backgroundjobs is still running. The wouldBlock check is
                // needed on systems with advisory locking, see
                // http://php.net/manual/en/function.flock.php#45464
                if (!$isLocked || $wouldBlock) {
                        echo "Another instance of cron.php is still running!" . PHP_EOL;
                        exit(1);
                }

                // Work
                $jobList = \OC::$server->getJobList();
                $jobs = $jobList->getAll();
                foreach ($jobs as $job) {
                        $job->execute($jobList, $logger);
                }

                // unlock the file
                flock($fp, LOCK_UN);
                fclose($fp);

        } else {
                // We call cron.php from some website
                if ($appMode == 'cron') {
                        // Cron is cron :-P
                        OC_JSON::error(array('data' => array('message' => 'Backgroundjobs are using system cron!')));
                } else {
                        // Work and success :-)
                        $jobList = \OC::$server->getJobList();
                        $job = $jobList->getNext();
                        if ($job != null) {
                                $job->execute($jobList, $logger);
                                $jobList->setLastJob($job);
                        }
                        OC_JSON::success();
                }
        }

        // Log the successful cron execution
        if (\OC::$server->getConfig()->getSystemValue('cron_log', true)) {
                \OC::$server->getConfig()->setAppValue('core', 'lastcron', time());
        }
        exit();

} catch (Exception $ex) {
        \OCP\Util::writeLog('cron', $ex->getMessage(), \OCP\Util::FATAL);
}