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Date: Fri, 19 Jun 2026 18:48:04 +0300
Message-ID: <1383126285.20260619184804@yandex.ru>
To: Mark Geisert <mark@maxrnd.com>, cygwin@cygwin.com
Subject: Re: Fwd: BUG?!: Running cygserver switches egid/primary group to
 4095(CurrentSession)
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From: Andrey Repin via Cygwin <cygwin@cygwin.com>
Reply-To: cygwin@cygwin.com
Cc: Andrey Repin <anrdaemon@yandex.ru>
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Greetings, Mark Geisert!

> 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?

Yes, of course, cygserver is started at boot as a service.

Here's full fstab

>> # /etc/fstab
>> #
>> #    This file is read once by the first process in a Cygwin process tree.
>> #    To pick up changes, restart all Cygwin processes.  For a description
>> #    see https://cygwin.com/cygwin-ug-net/using.html#mount-table
>>
>> none /mnt cygdrive noacl,binary,nouser,posix=0 0 0
>> W:/ /run ntfs acl,binary,nouser,posix=0 0 0
>> none /tmp usertemp binary,user,posix=0 0 0

W: is a small 8MB ramdrive, if you are interested.

Though, I just realized that I should probably set up /tmp as a per-user
mount. (Through fstab.d)
Please advise if so.


-- 
With best regards,
Andrey Repin
Friday, June 19, 2026 18:43:32

Sorry for my terrible english...


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