Please read alien's man page for general documentation.

Getting alien:

  The newest versions of alien are available at the alien home page; drop by
  http://kitenet.net/programs/alien/

  On metalab and its mirrors, alien is located in the
  pub/Linux/utils/scripts/ directory.

  You can also get rpm or deb packages of alien: 
  deb: ftp://ftp.debian.org/debian/unstable/binary-all/admin/alien_*.deb
  rpm: ftp://ftp.redhat.com/pub/contrib/noarch/alien-*.rpm

Other things you'll need:

  To use alien, you will need several other programs. Alien is a perl
  program, and requires perl version 5.004 or greater. If you use slackware,
  make sure you get perl 5.004, the perl 5.003 in slackware does not work
  with alien!

  To convert packages to or from rpms, you need the Red Hat Package Manager;
  get it from Red Hat's ftp site.

  If you want to convert packages into debian packages, you will need the
  dpkg, dpkg-dev, and debhelper packages, which are available on the Debian
  ftp site.

  To convert to/from stampede packages, you will need bzip2, get it from
	http://sourceware.cygnus.com/bzip2/index.html

  Attention, Slackware, Red Hat, and Stampede users: Bruce S. Babcock
  <babcock@math.psu.edu> has put together an "alien-extra"
  package of all the extra files you need to use alien on
  a Red Hat or Slackware system. (Debian systems automatically have the
  required files.)
  The Slackware version is at 
  	ftp://ykbsb2.yk.psu.edu/pub/alien/alien-extra.tgz
  The RedHat version is at
  	ftp://ykbsb2.yk.psu.edu/pub/alien/alien-extra.rpm
  The Stampede version is at
  	ftp://ykbsb2.yk.psu.edu/pub/alien/alien-extra.slp

Programs that use alien:

  I know of one program that acts as a frontend to alien - kpackviewer is a
  package viewer that can convert between package formats by using alien. Its
  homepage is at http://www.momentus.com.br/users/hook/kpackviewer.html

Please report any bugs in alien to the author: 

  Joey Hess <joeyh@debian.org>