Most of the main utilities are able to write there log files to a Unix Domain socket if configured that way. watchgnupg is a simple listener for such a socket. It ameliorates the output with a time stamp and makes sure that long lines are not interspersed with log output from other utilities.
watchgnupg is commonly invoked as
watchgnupg --force ~/.gnupg/S.log
This starts it on the current terminal for listening on the socket ~/.gnupg/S.log.
watchgnupg understands these options:
--force
--verbose
--version
--help