backup your mysql database everynight with a shell script.

To save your password protect mysql database into a file, use the mysqldump utility.

#!/bin/bash
DATABASE_NAME=name
MYSQL_USER=utilisateur
MYSQL_PASSWORD=password
mysqldump --user=$MYSQL_USER --password=$MYSQL_PASSWORD $DATABASE_NAME -q --single-transaction --complete-insert| bzip2 > $(date +%F-%T)_$DATABASE_NAME.sql.backup

Référence complète de mysqldump :
http://dev.mysql.com/doc/refman/5.0/fr/mysqldump.html