I am using Ubuntu 14.04 To run Processing, you need to have JAVA. By default, ubuntu do not come with JAVA pre-installed due to licensing issue (DAMN! These biz ppl is blocking the earth turning again). There are 2 type of java runtime you can install, one from openJDK and another one from Oracle. Processing2 at this time of writing only work with the later one. Follow this tutorial on how to install Oracle Java to your ubuntu machine. The process can take up to 3 hours if you have a slow Internet line. After successfully installed, you may proceed to download processing. I like to place my processing under /opt.