zentyal 3.0 has a frontend (System -> Import/Export Configuration), but if your wanting to cron it.
/usr/share/zentyal/make-backup
backups saved in /var/lib/zentyal/conf/backups/
Options available.
Usage:
./make-backup [OPTION]...
./make-backup --help
Options:
--config-backup (default backup mode)
--configuration-report --bug-report
--description <description>
--fallback-to-ro
--remote-backup <name>
--progress-id (only needed for web framework)
Sorry i know its a bit of an old topic, but i thought for completeness, i would add it here.