Supplemental groups count in Linux

NGROUPS_MAX is the maximum supplemental group count for a Unix login.

On Linux, it is 65536.

But on MacOS and NetBSD, it is 16 -- which is the old standard.

Even worse, MacOS has all but filled the supplemental groups with
gid's for its own housekeeping:

$ for II in `id -G -n`; do echo $II ; done
staff
everyone
localaccounts
_appserverusr
admin
_appserveradm
_lpadmin
_appstore
_lpoperator
_developer
_analyticsusers
com.apple.access_ftp
com.apple.access_screensharing
com.apple.access_ssh
com.apple.access_remote_ae

$ for II in `id -G -n`; do echo $II ; done | wc -l
      15

What a waste of space!  On Linux:

$ for II in `id -G -n`; do echo $II ; done
scott
adm
cdrom
sudo
dip
plugdev
lpadmin
sambashare
wireshark
libvirt
nordvpn

$ for II in `id -G -n`; do echo $II ; done | wc -l
11

Conclusion:  Linux is a modern OS, with much more administrative
flexibility.  Complex user-sharing configurations can be set
up -- encompassing, if needed, thousands of supplemental
groups.

p.s. If someone could run this on Windows and report the value,
I'd much appreciate it:

 - - %<- cut here - %<- - -
#include <stdio.h>
#include <limits.h>

int main (void)
{

printf("%d\n",NGROUPS_MAX);

return 0;
}

 - - %<- cut here - %<- - -


--
-v System76 Thelio Mega v1.1 x86_64 NVIDIA RTX 3090 Ti
   OS: Linux 6.12.3 Release: Mint 21.3 Mem: 258G
   "If a program is useless, it must be documented."