Installing redcar under Linux

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 open4
sudo apt-get install rubygems1.8
sudo apt-get install openjdk-6-jre´
sudo apt-get install firefox-dev
sudo 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.