# ownCloud Administrators Manual

# Background Jobs

A system like ownCloud sometimes requires tasks to be done on a regular base without blocking the user interface. For that purpose you, as a system administrator, can define background jobs which make it possible to execute tasks without any need of user interaction, e.g. database clean-ups etc. For the sake of completeness it is worth to know that additionally background jobs can also be defined by installed apps.

## Parameters

In the admin settings menu you can configure how cron-jobs should be executed. You can choose between the following options:

- AJAX
- Webcron
- Cron

## Cron-Jobs

OwnCloud requires various automated background jobs to be run. There are three methods to achieve this. The default way is AJAX and the recommended way is cron.

### AJAX

This option is the default option, although it is the least reliable. Every time a user visits the ownCloud page a single background job will be executed. The advantage of this mechanism is, that is does not require access to the system nor registration at a third party service. The disadvantage of this solution compared to the Webcron service is, that it requires regular visits of the page to get triggered.

### Webcron

By registering your ownCloud `cron.php` script address at an external webcron service, like e.g. easyCron, you ensure that background jobs will be executed regularly. To use such a service your server need to be reachable via the Internet.

Example

    URL to call: http[s]://<domain-of-your-server>/owncloud/cron.php

### Cron

Using the systems cron feature is the preferred way to run regular tasks, because it allows to execute jobs without the limitations which a web server may have.

Example

To run a cron job on a *nix system, e.g. every 15min, under the default web server user, e.g. www-data, you need to set-up the following cron job to call the cron.php script. Please check the crontab man page for the exact command syntax.

    # crontab -u www-data -e
    */15  *  *  *  * php -f /var/www/owncloud/cron.php