backup db :

 /usr/bin/mysqldump -u baznas -p'DgG9uX~id^wo' baznas_db>/home/baznas/public_html/backup_db/-`/bin/date +\%d-\%m-\%Y`.sql
delete backup before : 

 find /home/baznas/public_html/backup_db -type f -mtime +1 -exec rm {} +