I know there are Oracle DBs installed on my UNIX server. Is there any way to get those DB names? I'm using Sun OS.
You can also try ps -ef | grep -i pmon. Each running pmon process would be for one DB and base on the pmon name your database would be ora_pmon_<db sid>. There could be additional DBs that are not running currently but this would give you the active running database on a Sun box. Also check the /var/opt/oracle/oratab as mention above for the listing of the DBs if the DB admin is keeping the DB properly listed in oratab.