Rolling MySQL database backups

mysql-backup.sh

#!/bin/sh

# use with cron entries such as:
#3 */2 * * *     $HOME/bin/mysql-backup.sh dbname backupname hourly H
#8 1 * * *       $HOME/bin/mysql-backup.sh dbname backupname daily a
#33 2 1,8,15,23 * *    $HOME/bin/mysql-backup.sh dbname backupname weekly d
#33 2 28 * *   $HOME/bin/mysql-backup.sh dbname backupname monthly b

DB_NAME="$1"
BACK_ROOT="$2"
PERIOD_NAME="$3"
DATE_FMT="$4"
DB_PASSWORD="password1234"
DB_USER="backup"

DUMP_NAME="${BACK_ROOT}/${PERIOD_NAME}/${DB_NAME}.`date +%${DATE_FMT}`.sql"
DB_SERVER="127.0.0.1"
nice mysqldump -u $DB_USER -p$DB_PASSWORD -h $DB_SERVER $DB_NAME | gzip -1 --rsyncable >  "$DUMP_NAME.gz"

Please add automatic directory tree creation line 16