TechFAQ

There is an undocumented parameter _trace_files_public that if set to true changes the file permissions in the user_dump_dest directory when trace files are created to allow everyone to read them. This parameter can be checked with the following SQL. Beware that this is an undocumented parameter and should not be routinely set to true as some information in trace files can be used by hackers or malicious users. You can set this parameter by adding the following line to the init.ora file:
# allow trace files to be created with public permissions
_trace_files_public=true
# disable this feature:
#_trace_files_public=true
# or =>
_trace_files_public=false

Here is the SQL to check the value of this parameter:
SQL> select x.ksppinm name,y.ksppstvl value
2 from sys.x$ksppi x,sys.x$ksppcv y
3 where x.inst_id=userenv('Instance')
4 and y.inst_id=userenv('Instance')
5 and x.indx=y.indx
6 and x.ksppinm='_trace_files_public';
NAME
----------------------------------------------------------------
VALUE
--------------------------------------------------------------------------------
_trace_files_public
FALSE