Installed packages are obviously a subset of the available ones. Each of these entries stores, in the first place, the same fakefiles we just described, and some subtrees which, in their turn, contain symbolic links to each file owned by the package. In this way PackageFS provides ``by package'' system view and access: in fact, as the user with adequate privileges edits a symbolic link, he modifies the real system file.
Inside packages locations, there are two more subdirectories:
. Through them the user can access respectively
package dependencies and reverse dependencies. More specifically,
they hold symbolic links to these latter entities. If the dependency
referenced by a symbolic link is currently installed, the user may
visit its subtree. Otherwise the same link is simply in dangling state5.1, and will be automatically fixed if the dependent package is installed.
Available and installed packages subtrees are shown in figure 5.4.