EXPORT
======
exp help=y

TRACE
=======
exp 'user/pass' file=expa1.dmp log=expa1.log trace=y
10046 trace file in the user_dump_destination.

or 

select sid,serial#,program from v$session where program like '%exp% or %imp%;
execute dbms_system.set_sql_trace_in_session(sid,serial#,True);