The Prince CLI exits with a bogus 0 return code even on CLI option parsing errors:

$ prince --unknown
prince: error: unrecognized option `--unknown'
prince: error: Try 'prince --help' for more information.
$ echo $?
0

In this case it really should exit with a return code != 0, please. Thanks.

Woops! Thanks for picking that up, we will fix it in the next maintenance release, due shortly.

Today we have released Prince 9 rev 5, which fixes this issue. Thanks again for letting us know.