I am creating a deb package of a product which is part open source and part proprietary. In order to reuse the built in functionality of some distributions like Ubuntu to monitor a list of repositories and update the package when a new version comes available I will probably create such a repository.
The problem is that the proprietary part of the package depends on licenses which are valid for a limited interval versions (valid for all the versions in a course of a year). Which means that at some point of time when a new version is available it will be nice to at least warn the user that his license will not be valid for the new version.
Is there a way to do that check and interact with the user? I see that there are scripts in the deb package itself that can be executed before installation, but I have no idea if they can interact with the user and abort the package installation.
Any suggestions on how such a functionality can be created are appreciated.