10.8 How do I override a file installed by a package, so that a different version can be used instead?

Suppose a sysadmin or local user wishes to use a program "login-local" rather than the program "login" provided by the Debian login package.

Do not:

• Overwrite /bin/login with login-local.

The package management system will not know about this change, and will simply overwrite your custom /bin/login whenever login (or any package that provides /bin/login) is installed or updated.

Rather, do

• Execute:

       dpkg-divert --divert /bin/login.debian /bin/login
  

  in order to cause all future installations of the Debian login package to write the file /bin/login to /bin/login.debian instead.

• Then execute:

       cp login-local /bin/login
  

  to move your own locally-built program into place.

Details are given in the manual page dpkg-divert(8).