Configure scheduled tasks
ownCloud allows three methods for executing background jobs, as described in the ownCloud manual. By default, the AJAX mode is configured to run scheduled tasks.
If you prefer to use cron, edit the crontab by running the following command
$ sudo crontab -e
Add the following line at the end of the file:
*/15 * * * * su daemon -s /bin/sh -c "/opt/bitnami/php/bin/php -f /opt/bitnami/apps/owncloud/htdocs/cron.php > /dev/null 2>&1"
Note that the cron job will be executed by the daemon user.