I am trying to figure out if there is any limitation on how many users can
be part of a supplemental groups.

I have found references to NGROUPS_MAX, but I believe this refers to how
many groups one user can be apart of. I want to know how many users can be
part of a group (not login groups), i.e.:
groupname: user1, user2, user3, user4, ...

So I am looking at /usr/src/lib/libc/gen/getgrent.c.

It appears that a group can only as many users that can fit on one 1024
character line. Also, I don't see any way to wrap a group entry to
multiple lines. (If it is longer than 1024 characters, then the line --
the group entry -- is not used.)

I also see a reference to MAXGRP which is defined to 200. It looks like a
group entry can only have up to 200 members (users).

So is the answer to my question: a supplementary group can have up to 200
users as long as the line is less than 1024-characters long.

What is the purpose of using 200 as the max number of groups?

(And off-topic: is this similar to GNU's or other OS libraries?)

Thanks,

   Jeremy C. Reed
   http://www.reedmedia.net/