Add RAR file compression support to Ubuntu

While Zip is the main compression file format used on most desktop
computers, some people prefer to use the RAR format. To install sup-
port for extracting files from a RAR archive, use Synaptic to search for
and install unrar. Following this, File Roller—Ubuntu’s default archive
manager—will be able to extract files from RAR archives. You can also
use the command from the prompt by simply typing unrar e filename.rar,
replacing filename.rar with that which you downloaded. Note that unrar
doesn’t require a dash before the e command option.

Taken From ubuntu Kungfu