backup mysql databases with bash

#!/bin/bash

# modify the following to suit your environment

dir_backup="/home/user1/mysql_backup"
db_user=actual_username
db_pass=actual_password
db_host=localhost_or_actual-host

echo ""
echo "mySQL_backup"
echo "----------------------"
echo "* Rotating backups..."

# Deleting oldest backup.
rm -rf $dir_backup/04

mv $dir_backup/03 $dir_backup/04
mv $dir_backup/02 $dir_backup/03
mv $dir_backup/01 $dir_backup/02

mkdir $dir_backup/01

echo "* Creating new backup..."
mysqldump --opt -u $db_user -p$db_pass -h $db_host --all-databases | bzip2 > $dir_backup/01/mysql-`date +%Y-%m-%d`.bz2

echo "----------------------"
echo "Done"
exit 0