On systems that use the X11 window system, the DISPLAY variable is required to direct test output to the appropriate display. The display you specify here is used by JavaTest when running the AWT and Swing tests. For example:
testsystem:0.0

You may specify the value "$DISPLAY" to indicate that you wish to specify this value at the time you run the tests. If you specify "$DISPLAY", you must set the value of the DISPLAY system variable when you start JavaTest. For more information see the JavaTest User's Guide and Reference.