This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
CATALINA_HOME is an environment variable that Tomcat uses. If you're using Java 5.0 or newer, you can get the value by using the method java.lang.System.getenv(...). Look it up in the API documentation.