RPM Package Manager (RPM) is a package management system.
The name RPM variously refers to the .rpm file format, files in this format, software packaged in such files, and the package manager itself.
.rpm packages are rarely used in Ubuntu, since Ubuntu uses .deb packages instead. Ubuntu uses dpkg and APT for package management (and higher-level utilities like the Ubuntu Software Center).
When installing a program or library that is only available as an .rpm package, it is sometimes possible to install it in Ubuntu with the rpm command. But it is preferable to use alien to convert the .rpm package to a .deb package. alien can either automatically install the package itself (alien -i), or leave it for later installation using dpkg.
Occasionally, an .rpm package cannot be installed on Ubuntu even with alien or rpm. The packaged version may be specific to one or more non-Ubuntu operating systems that use .rpm packages natively (such as Fedora). The software might also install but not work properly, for the same reason. When this happens, if there is no .deb package available, it may be necessary to build the software from source.
