http://hallaweb.jlab.org/experiment/HAPPEX/opmanua/opmanual.html#HPXStartingpromptanalysis
However, after you have finished with a given run, I find one can't exit from root elegantly to start the next run. I get segmentation violations, etc. and root gets hung and does not respond to a .quit properly. This seems to be true whether or not I close the GUI out using "Exit GUI" button before trying to close root from the command line.
I find I can to a ctrl-z to put it in the background, do a "ps" at
the command line, identify the processes from the listing, then
do kill -9 # (where # are relevant process numbers). I am told
that, instead, multiple ctrl-C's followed by qqqqq might work as well.
I'll try that next time...