"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."