If you receive an error that BASE_DIRECTORY must be set when you try to start Contrast, it's an indication that you have a CATALINA_HOME directory already set in your system environment. Some products that use Tomcat require you to set this directory in the environment; but, unfortunately, it steps on our startup scripts.
The simplest way to resolve this error is to edit the CONTRAST_HOME/server/bin/start-teamserver.sh file, and set the CATALINA_HOME to Contrast's Tomcat directory by adding:
# Address hard-coded environment variable for CATALINA_HOME - Set this directory to your
# $CONTRAST_HOME/server directory
set CATALINA_HOME=/opt/contrast/server