In linux I did following and hope this will work will SUN also

1. there should be a file oratab in etc directory changed the setting to Y.

2. write a script which will further call to scripts DBSTART and DBSHUT(For starting and shutting down

3. save this script into /etc/rc.d/init.d directory

4. Make it executable by chmod -

5. issue command chkconfig --add scriptname

6. restart the server.

hope this work