Hi!
You can try
mysqldump -c YOURDBNAME > /path/yourdbname.sql
if it was horde you want to backup to your /opt/backups/
mysqldump -c horde > /opt/backups/horde.sql
OR even better, if you want to put a date
date=date -I
mysqldump -c horde > /opt/backups/horde-$date.sql
Best rgds, Ergin