group '545' does not exist ?

[Marco Atzeri]

On 04/12/2025 21:50, Brian Inglis via Cygwin wrote:
> On 2025-12-04 08:00, Jon Turney via Cygwin wrote:
>> Actually, I think this is a shortcoming of the cygwin version of newgrp.
>> The SUS description [1] of newgrp allows a numeric group id to be 
>> specified.
>> (In fact, it includes the clarifying remark "If group is a non- 
>> negative numeric string and exists in the group database as a group 
>> name, the numeric group ID associated with that group name will be 
>> used as the group ID", which suggests a, um, straightforward 
>> implementation)
>> But it seems that our implementation only currently handles a group 
>> name (See [2]).
>> [1] https://pubs.opengroup.org/onlinepubs/7908799/xcu/newgrp.html
> 
> That's OG SUSV2 1997 - current is at:
> 
>      https://pubs.opengroup.org/onlinepubs/9799919799/utilities/newgrp.html
> 
>> [2] https://cygwin.com/cgit/newlib-cygwin/tree/winsup/utils/newgrp.c#n166


Thanks Jon, Brian,

do you know also why the group in /etc/passwd is ignored and
"Nobody/Nessuno" is used ?

$ cat passwd
Marco:*:197608:545:U-DESKTOP-L2T1NQ9\Utente,S-1-5-21-1151457081-841113255-780074606-1000:/home/Marco:/bin/bash

$ id
uid=197608(Marco) gid=197121(NESSUNO) 
groups=197121(NESSUNO),545(Users),4(INTERACTIVE),66049(ACCESSO 
CONSOLE),11(Authenticated Users),15(Questa organizzazione),113(Account 
locale),4095(CurrentSession),66048(LOCALE),262154(Autenticazione 
NTLM),401408(Livello obbligatorio medio)

$ uname -svr
CYGWIN_NT-10.0-26200 3.6.5-1.x86_64 2025-10-09 17:21 UTC

Regards
Marco