path: root/java/java-rxtx/GroupMembership.txt

In order to use a program that makes use of rxtx, you must be a member
of the groups:
 * uucp: for access to hardware devices in /dev
 * lock: for access to hardware lockfiles in /run/lock/lockdev

Most documentation indicates that you must be in one or the other,
depending on your distro; you must actually be in both.