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Date: Wed, 11 Mar 2026 16:16:32 +0100
To: cygwin AT cygwin DOT com
Subject: Re: HYPER-V VMs: Cygwin /bin/getent group 'Virtual Machines' cannot
 find the group
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From: Corinna Vinschen via Cygwin <cygwin AT cygwin DOT com>
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On Mar  3 09:26, Aurélien Couderc via Cygwin wrote:
> On Mon, Mar 2, 2026 at 8:19 PM Martin Wege via Cygwin <cygwin AT cygwin DOT com> wrote:
> >
> > Hello,
> >
> > we use HYPER-V virtual machines on Windows 10 and Windows 11. It seems
> > they use a "special" kind of group called 'Virtual Machines', which
> > Cygwin (3.6.5) /bin/getent cannot lookup:
> >
> > getent group 'Virtual Machines'
> > <nothing>
> >
> > Does anyone have ideas or clues how to get getent group to work with
> > this kind of Windows group?
> >
> > We want the Cygwin gid for that group, and use Cygwin commands to work
> > with those files...
> 
> Déjà vu
> 
> 1. Please read https://cygwin.com/pipermail/cygwin/2025-July/258505.html
> 
> 2. Try this:
> getent group "NT VIRTUAL MACHINE+Virtual Machines"
> For me, with default (empty, except comments) /etc/nsswitch.conf, it
> does not work. Which I consider a bug.

It's not a bug, it's a feature.  Truly so.  Keep in mind that there's
no easy translation from arbitrary SIDs to 32 bit uid/gid values and
vice versa.  So every time, Microsoft adds YA arbitrary SID not following
the already implemented and supported schemes, the bijective mapping
has to be implemented manually.

Done in the main branch.


Corinna

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