By convention, the base Tomcat directory (e.g.
/usr/local/apache-tomcat-5.5.2831) is referred to as
$CATALINA_HOME. As a convenience, you should create a
$CATALINA_HOME environment variable. For UNIX operating systems one typically modifies a startup file like ~/.bash_login to set and export shell variables while Mac users typically set and export environment variables in
.bash_profile. For Windows, go to
Start -> Control Panel -> System -> Advanced -> Environment Variables and set your Tomcat environment variables via the GUI.