How to obtain trace name for current Oracle session

How to obtain trace name  for current Oracle session.

select rtrim(c.value,'/') || '/' || d.instance_name || '_ora_' || ltrim(to_char(a.spid)) || '.trc'
from v$process a, v$session b, v$parameter c, v$instance d
where a.addr = b.paddr
and b.audsid = sys_context( 'userenv', 'sessionid')
and c.name = 'user_dump_dest'
and rownum < 50;