Displays the phase of the moon on the root window
xphoon [-b] [-t interval [-i]] [-s] [-display name]
Xphoon sets the X root window to a picture of the moon in its current phase, including the partial lighting of the dark side by reflected earthlight.
-b
Defeats the earthlight feature, forcing the dark side to be black.
-t
Have xphoon keep running and update the picture every interval minutes. (Normally, xphoon just sets the root picture and exits.)
-i
Forks a background process and prints the process-id to stdout. Useful if you want to make menu commands to refresh or kill xphoon.
-s
Rotate the whole picture 180 degrees, resulting in a moon picture as viewed fom the Southern hemisphere.
-demo
Demonstrate xphoon by rapidly stepping through moon phases.
The original motivation for this program was that xsetroot was too slow. Loading a full-screen bitmap took about 15 seconds. We made a trivial program that had fullmoon.bitmap compiled in, and it ran in less than a second. (And incidentally, the executable was smaller than fullmoon.xbm.) Then later we came up with the phase hacking, the earthlight, and the auto-scaling.
phoon(1), xsetroot(1)
Copyright (C) 1988, 1991 by Jef Poskanzer and Craig Leres.
The moon-phase computation is from "moontool.c" by John Walker.