Best (for me) mysql dump script

The best for me mysql dump script,
it can be configured by cron dates,
create backup many times per day, and store fore one week.

CRON:
0 0,6,12,18 * * * /backup/mysql/backup-mysql-all-separate.sh

SCRIPT:
#!/bin/bash
OUTPUT="/backup/mysql/`date +%a/hour_%H`"
echo $OUTPUT
# if not exists
if [ ! -d "$OUTPUT" ]; then mkdir -p $OUTPUT; fi
# /bin/rm -f -v "$OUTPUT/*.gz" > /dev/null 2>&1
/bin/rm -f -v $OUTPUT/*.gz
databases=`/usr/bin/mysql -e "SHOW DATABASES;" | tr -d "| " | grep -v Database`
for db in $databases; do
if [[ "$db" != "information_schema" ]] && [[ "$db" != _* ]] && [[ "$db" != "performance_schema" ]] ; then
echo "Dumping database: $db"
/usr/bin/mysqldump --force --opt --events --databases $db > $OUTPUT/$db.sql
/bin/nice -n +19 /usr/bin/ionice -c3 /bin/gzip -9 $OUTPUT/$db.sql
fi
done