Puzzled by apt

[hazel]

When I run deborphan, I get a list of libraries that are truly orphaned, i.e. they have nothing dependent on them (except perhaps other orphans). But when I use apt-get remove to remove these, I get a list of supposedly unnecessary packages which includes a lot more. Some of these are things like unused gnome applets which deborphan would not be expected to pick up as it only looks in the library folders, but some are really useful things that I would not want to get rid of: for example, gdm and the packages comprising lxde.

Why does the apt system think these are unnecessary?

[reed9]

I think this usually comes up because packages like gdm are usually not explicitly installed, but pulled in from some metapackage, and then the metapackage is subsequently removed.

I've personally never had luck with any distros auto-tools for removing orphaned packages. Somehow there are always things I want and need that get included.

[hazel]

That's probably the explanation then. I installed gdm by hand because I needed a display manager (I don't like using startx). But apt probably thinks it's a left-over from an installation of gnome. And in the case of lxde, I think I installed the whole package and then got rid of the bits I didn't want.