Users can access log files using operating system commands and functions and also using Database Studio or Database Manager CLI.
On Unix and Linux, unprivileged operating system users cannot access log files; only members of the special operating system user group <sdba_group> can do so.
Withdraw the server authorization for reading database files from all DBM operators that should not have access to log files.
In Database Manager CLI, withdraw the DBFileRead server authorization.
See Database Manager CLI, user_put
Defining Clear Authorizations for Users
Database Administration, Special Operating System Users and Groups (Unix and Linux)