How do I discover what package provides a certain file?

[Eric Dunbar]

Hi all, I was trying to figure out what package on my Ubuntu 6.06 LTS
box provided a certain file.

In YellowDogLinux (FC-based distro) I've always used:

yum provides insertfilenamehere

And yum (yellowdog updater modified) spits out the package to which
that file belongs.

I've scoured the man pages for apt-* (including aptitude) without
success. It seems the search functionality in apt-get is  limited,
poorly documented or both.

I used Synaptic successfully, but the only reason it found the package
is that the file name was actually part of the package description.

1. Anyone know how to easily search the files installed by packages?

2. Second though, anyone know how to use apt-get et al. to search for
packages (like yum find xyz)? aptitude can do it but I really don't
like its interface (its user interface could handle a major overhaul
-- the irony is that it's designed so people don't have to fiddle with
apt-get but it's designed for people who read man pages and memorise
commands ;-)... exactly the crowd who don't need something like
aptitude ;-P)