Debian :: Backing Up Configuration Files Using BAK

Before I used to make a copy of configuration file and give the end of the file name as 'something.conf.bkp' . Later realized it was a mistake. The correct wording should end in .bak and not bkp .

As per (See apt.conf(5) manpage, section DIRECTORIES, last paragraph.)

The Ignore-Files-Silently list can be used to specify which files APT should silently ignore while parsing the files in the fragment directories. Per default a file which end with .disabled, ~, .bak or .dpkg-[a-z]+ is silently ignored. As seen in the last default value these patterns can use regular expression syntax.