Editing GNU coding standards (section)

==Files==

The standards require that all programs be able to operate when <code>/usr</code> and <code>/etc</code> are [[mount (computing)|mounted]] read-only.  Therefore, files that are modified for internal purposes (log files, lock files, temporary files, etc.) should not be stored in either <code>/usr</code> or <code>/etc</code>.  An exception is made for programs whose job it is to update system configuration files in <code>/etc</code>.  Another exception is made for storing files in a directory when the user has explicitly asked to modify a file in the same directory.