(Gary, please do not shoot first!)
Yes, I know gpsmon is unmaintained. Yes, I know cgps is the way to go. But gpsmon provides something that no other tool does, direct access.
When bringing up a new system, where you are not even sure if /dev/ttyS02 or /dev/ttyACM0 is the one, it helps.
I understand that it must duplicate functionality of both gpsd and cgps. So it is a burden to maintain.
I have a new system, and gpsmon fails with an assertion. I am scared to open an issue :-)
Perhaps we should drop it? I can write the obituary notice.