You can do it in different ways.

1. Write a shell script, that would trace throgh the alert_sid.log file and post you the results on the database's status.

2. If you are running the oracle tools like OMS, then using OEM you can create events to fire (send you a mail/paging)
if the database is down

For examples on the scripts check oracle magazine site tips, that has a load of scripts that you can make use of.


[url]http://www.oracle.com/oramag/[/url]

Good luck
Sam