unrar is a free software version of the non-free unrar utility that exists on many GNU/Linux systems today. It uses the GPL'd UniquE RAR Library by Christian Scheurer and Johannes Winkelmann. This program is a simple command-line front-end to this library, and can list and extract RAR archives. It does not rival the non-free unrar in terms of features, but special care has been taken to ensure it meets most user's needs and it is hoped that GUI archivers such as GNOME's (file-roller) and KDE's ark will use this utility as a back-end.

Extract files from rar archives.
  -x, --extract              Extract files from archive (default)
  -t, --list                 List files in archive
  -f, --force                Overwrite files when extracting
      --extract-newer        Only extract newer files from the archive
      --extract-no-paths     Don't create directories while extracting
  -p, --password             Decrypt archive using a password
  -?, --help                 Give this help list
      --usage                Give a short usage message
  -V, --version              Print program version
Report bugs to <benasselstine@canada.com>.

You can download the latest version here.