Alien converts an RPM package file into a Debian package file or Alien can install an RPM file directly. This is not the recommended way to install software packages in Ubuntu. If at all possible, install packages from Ubuntu's repositories using Add/Remove, apt-get, or the Synaptic Package Manager. Package dependency conflicts may occur when attempting to install RPM packages. The Synaptic Package Manager may be able to fix or remove any broken packages.
Install Alien
Add the Universe repository to the sources list from the System menu System > Administration > Software Sources.
Open a Terminal from the Applications menu Applications > Accessories > Terminal.
In a terminal, enter:
sudo apt-get install alien
Installing an RPM file directly
In a terminal, enter:
sudo alien -i package_file.rpm
Converting the RPM file to a Debian package
In a terminal, enter:
sudo alien package_file.rpm
Installing the converted Debian package
Either use gdebi, or in a terminal, enter:
sudo dpkg -i package_file.deb
Additional Help
In a terminal, enter:
alien -h