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Date: Thu, 18 Jun 2026 00:19:38 -0700
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Subject: Re: Fwd: BUG?!: Running cygserver switches egid/primary group to
 4095(CurrentSession)
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From: Mark Geisert via Cygwin <cygwin@cygwin.com>
Reply-To: Mark Geisert <mark@maxrnd.com>
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Hi Andrey,

On 6/17/2026 10:36 AM, Andrey Repin via Cygwin wrote:
> Greetings, Mark Geisert!
> 
>> On 6/8/2026 3:35 PM, Lionel Cons via Cygwin wrote:
>> [...]
>>> If I run without cygserver id -a returns
>>> $ id -a
>>> uid=197620(lcons) gid=197121(Kein)
>>> groups=197121(Kein),197615(docker-users),545(Benutzer),559(Leistungsprotokollbenutzer),4(INTERAKTIV),66049(KONSOLENANMELDUNG),11(Authentifizierte
>>> Benutzer),15(Diese Organisation),113(Lokales
>>> Konto),4095(CurrentSession),66048(LOKAL),262154(NTLM-Authentifizierung),401408(Mittlere
>>> Verbindlichkeitsstufe)
>>>> but if I start cygserver each new session has gid=4095(CurrentSession)
>>> as egid/primary group for new terminals
>>> $ id -a
>>> uid=197620(lcons) gid=4095(CurrentSession)
>>> groups=4095(CurrentSession),197121(Kein),197615(docker-users),545(Benutzer),559(Leistungsprotokollbenutzer),4(INTERAKTIV),66049(KONSOLENANMELDUNG),11(Authentifizierte
>>> Benutzer),15(Diese Organisation),113(Lokales
>>> Konto),66048(LOKAL),262154(NTLM-Authentifizierung),401408(Mittlere
>>> Verbindlichkeitsstufe)
> 
>> I'm unable to reproduce the issue, but I'm a little unsure I have the
>> complete list of steps to do so.  Let's start with these questions:
> 
>> Is your system part of a Windows domain?
> 
>> How exactly are you starting cygserver?
> 
>> When you say "each new session" do you mean opening a new Cygwin Terminal
>> that presents the usual bash+mintty user CLI?  Or is it some other method?
> 
> I think I've observed a related issue.
> I have /tmp set up as user mount, and from time to time, when I log in, it
> points to %WinDir%\TEMP rather than to the current user's %TEMP%, in turn
> making many tools dysfunctional.
> 
> I have to restart cygserver for it to work.

That's interesting.  Do you also have cygserver set up to start on 
Windows boot?  And could you please paste your mount /tmp command so I 
can set that up identically?
Thanks!

..mark

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