Description:

whohas is a command line tool that allows querying several package
lists at once - currently supported are Arch, Debian, Fedora, Gentoo,
openSUSE, Slackware (and linuxpackages.net), Source Mage, Ubuntu,
FreeBSD, NetBSD, OpenBSD, Fink and MacPorts. whohas is written in Perl
and was designed to help package maintainers find ebuilds, pkgbuilds
and similar package definitions from other distributions to learn
from.

However, it can also be used by normal users who want to know:
- Which distribution provides packages on which the user depends.
- What version of a given package is in use in each distribution, or
in each release of a distribution (implemented only for Debian).