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."

On 8 Dec 2024 05:12:19 GMT, vallor wrote:

> 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.

Linux is the only real “industrial-strength” OS fit for the 21st century.

On Sun, 8 Dec 2024 06:55:25 -0000 (UTC), Lawrence D'Oliveiro
<ldo@nz.invalid> wrote in <vj3fss$3l3q8$5@dont-email.me>:

> On 8 Dec 2024 05:12:19 GMT, vallor wrote:
>
>> 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.
>
> Linux is the only real “industrial-strength” OS fit for the 21st
> century.

Well, when it comes to supplemental groups, I'm not so sure...I suspect
it might be a 32-bit field on Windows, but I don't have a Windows
machine to check that on.

--
-v System76 Thelio Mega v1.1 x86_64 NVIDIA RTX 3090 Ti
OS: Linux 6.12.3 Release: Mint 21.3 Mem: 258G
"He's dead, Jim. Get his ears! - Spock"

On 12/8/2024 12:12 AM, vallor wrote:
> 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 - %<- - -

D:\temp>tcc ngroups.c -o ngroups.exe
ngroups.c:6: error: 'NGROUPS_MAX' undeclared

On 8 Dec 2024 07:31:59 GMT, vallor wrote:

> ... I don't have a Windows machine to check that on.

I don’t any of the Windows fan(atic)s here even have the nous to
understand the question.

On Sun, 8 Dec 2024 19:23:50 -0500, DFS <guhnoo-basher@linux.advocaca>
wrote in <vj5daf$30up$2@dont-email.me>:

> On 12/8/2024 12:12 AM, vallor wrote:
>> 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 - %<- - -
>
>
> D:\temp>tcc ngroups.c -o ngroups.exe
> ngroups.c:6: error: 'NGROUPS_MAX' undeclared

No POSIX for you.

Seriously, though, try this:

#define _POSIX_
#include <stdio.h>
#include <limits.h>

int main (void)
{

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

return 0;
}

I know the answer though, because I downloaded tcc and looked
in limits.h -- which you could have done. (But I don't think
the value in there properly reflects the system value -- couldn't
find a prototype for getgroups(3).)

--
-v System76 Thelio Mega v1.1 x86_64 NVIDIA RTX 3090 Ti
OS: Linux 6.12.3 Release: Mint 21.3 Mem: 258G
"Windows: just another pane in the glass."

On Mon, 9 Dec 2024 03:45:11 -0000 (UTC), Lawrence D'Oliveiro
<ldo@nz.invalid> wrote in <vj5p46$8isq$3@dont-email.me>:

> On 8 Dec 2024 07:31:59 GMT, vallor wrote:
>
>> ... I don't have a Windows machine to check that on.
>
> I don’t any of the Windows fan(atic)s here even have the nous to
> understand the question.

DFS almost had the answer, if he'd just looked in limits.h.

BTW, tcc is smarter on Linux:

$ tcc -o try_ngroups_max_tcc try_ngroups_max.c
$ ./try_ngroups_max_tcc
65536

--
-v System76 Thelio Mega v1.1 x86_64 NVIDIA RTX 3090 Ti
OS: Linux 6.12.3 Release: Mint 21.3 Mem: 258G
"Do radioactive cats have 18 half-lives?"

On 12/8/2024 11:06 PM, vallor wrote:
> On Sun, 8 Dec 2024 19:23:50 -0500, DFS <guhnoo-basher@linux.advocaca>
> wrote in <vj5daf$30up$2@dont-email.me>:
>
>> On 12/8/2024 12:12 AM, vallor wrote:
>>> 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 - %<- - -
>>
>>
>> D:\temp>tcc ngroups.c -o ngroups.exe
>> ngroups.c:6: error: 'NGROUPS_MAX' undeclared
>
> No POSIX for you.
>
> Seriously, though, try this:
>
> #define _POSIX_
> #include <stdio.h>
> #include <limits.h>
>
> int main (void)
> {
>
> printf("%d\n",NGROUPS_MAX);
>
> return 0;
> }

$ tcc ngroups.c -o ngroups.exe
In file included from ngroups.c:3:
d:/computer/apps/compilers/tcc/tcc-0.9.27/include/limits.h:105: warning:
PATH_MAX redefined

$ ngroups
16

Obviously 16 isn't the max number of user groups you can create on
Windows. I can't find a max value online. I did find that a user can
be a member of a maximum of ~1015 groups.

> I know the answer though, because I downloaded tcc and looked
> in limits.h -- which you could have done.

I was going to... but my balls started itching and I had to take care of
that.

> (But I don't think
> the value in there properly reflects the system value -- couldn't
> find a prototype for getgroups(3).)

Linux:
$ sudo groupadd demo
$ sudo groupdel demo

Windows:
$ sudo net localgroup demo /add
$ sudo net localgroup demo /delete

To show groups:
$ net localgroup

Aliases for \\DFS-WIN11PRO
-------------------------------------------------------------------------------
*Access Control Assistance Operators
*Administrators
*Backup Operators
*Cryptographic Operators
*Device Owners
*Distributed COM Users
*Event Log Readers
*Guests
*Hyper-V Administrators
*IIS_IUSRS
*Network Configuration Operators
*OpenSSH Users
*Performance Log Users
*Performance Monitor Users
*Power Users
*Remote Desktop Users
*Remote Management Users
*Replicator
*System Managed Accounts Group
*User Mode Hardware Operators
*Users

That's 21 groups that were created automatically during install and
configuration (I didn't manually create any of them).