groupmod(8) on OpenBSD
The text db37bb43ae06, as OpenBSD 6.0, OpenBSD 5.9, OpenBSD 5.8, OpenBSD 5.7, OpenBSD 5.6, OpenBSD 5.5, OpenBSD 5.4 shipped it.
modify an existing group on the system
Flags it lists
-
-g -
-n -
-o -
-v