save :
sudo -u mysql mysqldump --protocol=socket -S /var/run/mysqld/mysqld.sock --all-databases -p | bzip2 -c > databasebackup.sql.bz2

restore :
bzip2 -d databasebackup.sql.bz2
sudo -u mysql --protocol=socket -S /var/run/mysqld/mysqld.sock < databasebackup.sql

si droits root (création de base, etc...)

sudo -u mysql -u root -p --protocol=socket -S /var/run/mysqld/mysqld.sock < databasebackup.sql