Major Description
it doesn't make any sense for activemq-admin to load the SUNJMX env var from /etc/activemq.conf since if activemq-admin is run on the same system that the broker runs on in many cases the com.sun.management.jmxremote.port system property will be set in there. Since the activemq-admin script now tries to use the same port that the broker is already using the script now fails to run.
You could argue that there is no point for the activemq-script to even use the SUNJMX variable at all, since there is little point in enabling a JMX connector for the script.
However in the attached patch all I've done is to reset the SUNJMX var so that it doesn't use what is set in /etc/activemq.conf.