/dev/zero

I’m quickly becoming a fan of Gentoo.
I don’t think it will be replacing Ubuntu on my laptop, but I’m finding that for a “source based” system, it’s very easy to use. It doesn’t install anything you don’t absolutely need until you specifically ask for it, but when you do, it’s pretty painless. You just have to put up with it taking a little longer than other distros to get installed, since it has to download the source, then compile it.