How to make trace files visible to all users?

To make trace files visible to all users, set the parameter _TRACE_FILES_PUBLIC=TRUE, this is undocumented parameter. This parameter requires a restart of instance to take into effect.

SQL> alter system set “_TRACE_FILES_PUBLIC”=true scope=spfile;

System altered.

Shows the trace file is accessible by all users, you may have change permissions on the user_dump_dest folder
-rw-r–r– 1 oracle oinstall 1433 Feb 21 21:07 test_ora_26729.trc

View the following link to find if parameter can be modified without restart or requires a restart.

Internal parameters