Alien is a program that converts between the rpm, dpkg, stampede slp, and slackware tgz file formats. If you want to use a package from another distribution than the one you have installed on your system, you can use alien to convert it to your preferred package format and install it.
Despite the large version number, alien is still (and will probably always be) rather experimental software. It has been used by many people for many years, but there are still many bugs and limitations.
Alien should not be used to replace important system packages, like sysvinit, shared libraries, or other things that are essential for the functioning of your system. Many of these packages are set up differently by Debian and Red Hat, and packages from the different distributions cannot be used interchangably. In general, if you can't uninstall the package without breaking your system, don't try to replace it with an alien version.
News
alien 8.76 released with these changes
- Avoid using hostname -f for portability to unix systems, such as Solaris, where any options _set_ the hostname.
- Fix bash shebang and recognise bash scripts as editable shell scripts when converting to deb. Closes: #532330 (Thanks, Bruce Stephens)
alien 8.75 released with these changes
- Simplified rules file.
- Modify maintainer scripts from rpm files to use /bin/bash rather than /bin/sh. Many such scripts are only tested on systems where /bin/sh is bash, and contain bashisms, which can cause trouble when converting the rpm to be used on eg, the Debian family of distributions, where /bin/sh can legitimatly be dash. Closes: #495971
Downloading alien
Alien is available as the alien package in Debian.
Currently the best place to download the tarball is from http://packages.debian.org/unstable/source/alien
Its git repository is git://git.kitenet.net/alien
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.
To convert packages to or from rpms, you need the Red Hat Package Manager; get it from its website.
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 packages site. You'll also need gcc, and make.
Attention, all linux users who don't use Debian: Bruce S. Babcock has put together a package of all the extra files you need to use alien on a non-Debian distribution. It's called "alien-extra", and you can download it from his ftp site.
I've blogged a few times about alien. Alien use patterns examines who I think is using alien now, and this post gives some historical background.
Also of interest is my feature comparison of the package formats alien supports.