How to find the trace file name?

To find the trace file one using oradebug one can find it using the example below:

SQL> oradebug mysetpid
Statement processed.

SQL> oradebug tracefile_name

If you try to run the above command without attaching to a session it will return ORA-00074
SQL> oradebug tracefile_name
ORA-00074: no process has been specified