From the blog you linked: &quot;Dpkg keeps a checksum of the last installed version of configuration file. When it must install a new version, it calculates the checksum of the currently installed file and if it doesn’t match anymore, <i>it knows that the user has edited the file. In that case, instead of overwriting the configuration file, it asks the user what to do</i>.&quot;<p>If you didn&#x27;t modify the system config you don&#x27;t get prompted about what to do.