How to find the Oracle session trace files

I was requested to provide details of a database error to be found in the Oracle session trace file. Where do I have to look for it?

The exact location depends on the configuration of your Oracle installation. For default Oracle 9.2 and 10g configurations, the session trace files are in the
$ORACLE_BASE/<database-instance-name>/udump directory. For 11g, they are in the $ORACLE_BASE/diag/<database-instance-name>/<database-instance-name>/rdbms/trace directory. Look for *.trc files.

(If you accesses the corporate database, you will need to have your dba to get the info and the dba will know where to look for Oracle session trace files.)