mkdir /home/sqlbackup

vi /usr/local/sbin/mysqlbackup.sh

#!/bin/sh
datum=`/bin/date +%Y%m%d-%H`
/usr/bin/mysqladmin --user=root --password=yourrootsqlpassword stop-slave
/usr/bin/mysqldump --user=root --password=yourrootsqlpassword --lock-all-tables \
--all-databases > /home/sqlbackup/backup-${datum}.sql
/usr/bin/mysqladmin --user=root --password=yourrootsqlpassword start-slave
for file in "$( /usr/bin/find /home/sqlbackup -type f -mtime +2 )"
do
/bin/rm -f $file
done
exit 0

chmod 755 /usr/local/sbin/mysqlbackup.sh

crontab -e

0 */3 * * * /usr/local/sbin/mysqlbackup.sh &> /dev/null