In fact, here's the pkgindex script and what it's indexed on our systems. These benefits probably wouldn't be enough if we had to make all those links by hand. But we've got a script called pkglink that does it all for us. These files are used in the indexing. If you wanted to see each directory and link it makes, use the -v option.
Some packages have libraries or other files of the same exact name.
Let's say you pkglink in emacs, and then xemacs - pkglink will likely fail at some point in the xemacs install. For the bold, pkglink will do the entire tree in one whack. Then we install software as ourselves. C. pkglink and pkgindex have man pages - read them. If you want to do all that work over again for whatever OS you run, go ahead.