usermod me -G http

me@poot$ id
uid=1234(me) gid=100(users) groups=6(disk),10(wheel),50(games),91(video),92(audio),93(optical),95(storage),100(users)

me@poot$ id me
uid=1234(me) gid=100(users) groups=100(users),33(http)

Log in and out again. id updates on login, id [uid] uses [m]/etc/group[m], it seems - forgetting the -a flag (--append) removes all your other groups.

I'm not sure if this will help but maybe the modes need to check the script for the reply because someone might of screwed it up