I think you might miss the izPack CheckedHelloPanel , which (according to online docs) checks the registry to see if another version has been installed, and asks if you want to install the second version.
OTOH ... if you mean that the installer should be able to upgrade to the previous version in place, this is a very difficult problem, and I still have to meet the installer installer, who even tries to solve the problem.
EDIT On platforms other than Windows, there is a fundamental problem. If the application can be installed in a non-standard place, it is impossible to say with 100% certainty if a copy (of the same or another version) was previously installed. And this may be the reason that CheckedHelloPanel only supports detection of an old version in Windows.
As said, izPack is open source, so if you can find a methodology for discovering a previous version on Linux, you can change the CheckedHelloPanel to implement it. And maybe izPack will accept the patch. In any case, I recommend that you first look at this approach before switching the tool that you are otherwise happy with. (Especially if what you want to do simply cannot be done on Linux.)
Stephen c
source share