For such a project, I think a different structure would make more sense. A structure where each supported package manager is a module on its own (like module/pacman.sh) and contains all the logic for this specific package manager. Those modules would only contain functions. And the main script with the main logic and loads in the module would not know or check what package manager it uses, but instead just runs the functions that are named the same in each module. But that would obviously require a major rewrite.