Installing redcar with sudo gem install redcar ends up in this error Building native extensions. This could take a while... ERROR: Error installing redcar: ERROR: Failed to build gem native extension. I installed these additional packages: sudo apt-get install open4sudo apt-get install rubygems1.8sudo apt-get install openjdk-6-jre´sudo apt-get install firefox-devsudo apt-get install ruby-dev and then it worked .... Maybe the last one is the most essential one and all the others are not necessary ......