by keivn dodd on Fri Dec 12, 2008 12:08 am
-G, --groups group,...
With this option a list of supplementary groups can be speci-
fied, which the user should become a member of. Each group is
separated from the next one only by a comma, without whitespace.
If not specified, the default from /etc/default/useradd is used.
-g, --gid gid
The group name or number of the user's main group. The group
name or number must refer to an already existing group. If not
specified, the default from /etc/default/useradd is used.
At first glance -g and -G appear to have different functionality until you realize -g will resolve group names to gids.