A small utility returning the state of daylight ("day", "night", "gray") for any location, date, and time.
Intended use:
cp radio-config-`./radioday jo65mr`.cfg radio-config.cfg
or
./radioapp radio-config-`./radioday jo65mr`.cfg
with three time-specific files: radio-config-day.cfg, radio-config-night.cfg, and radio-config-gray.cfg.