Re: HEADSUP: New getent tool to read passwd and group data

[Corinna Vinschen <corinna-cygwin@cygwin.com>]

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On Feb 21 21:27, Corinna Vinschen wrote:
> For some reason the original mail didn't make it to the list.
> 
> I assume this is because the mail body contains raw email addresses.
> Can you please filter them out before sending?  Thanks!
> 
> On Feb 21 12:47, Pierre A. Humblet wrote:
> > > -----Original Message-----
> > > From: cygwin-apps-owner[...]
> > >  On Behalf Of Corinna Vinschen
> > > Sent: Thursday, February 20, 2014 14:38
> > > To: cygwin-apps[...]
> > > 
> > > Hi guys,
> > > 
> > > 
> > > I just uploaded the new getent package and sent the announcement,
> > > 
> > > I'm repeating myself here because this is really important and I'm not sure
> > > everybody on this list reads the cygwin and cygwin-announce lists.
> > > 
> > > In short, we want to get rid of the requirement to maintain /etc/passwd and
> > > /etc/group files, per http://cygwin.com/ml/cygwin/2014-02/msg00306.html
> > > 
> > > In future, tools and scripts, especially service installation helper scripts like
> > > my ssh-host-config, must not rely on being able to grep user and group
> > > information from /etc/passwd and /etc/group.
> > > 
> > > Rather, the scripts should be changed to use the getent tool as soon as
> > > possible.  Usage for checking passwd:
> > > 
> > >   $ getent passwd <username...>
> > > 
> > > I'd like to ask all maintainers providing such scripts, including myself, to look
> > > into their packages and fix them to use the getent tool.
> > > 
> > 
> > Corinna,
> > 
> > For packages such as exim we need to find the uid of System and of Administrator, which the user can set any which way in passwd.
> > So we lookup the SID (not the username) to get the uid (or gid).
> 
> The SID of the administrator or the SID of the administrors group?
> The SID of the local administrator makes only marginal sense to me.
> What do you need it for?
> 
> > Is there an equivalent mechanism using getent ?
> > Else, could Cygwin disregard the passwd entries for these 2 users and use only the fixed values determined by the mapping from Windows? 
> 
> You should not have to expect a name change for the SYSTEM and the
> Administrators account.  It should be entirely sufficient to check for
> the user Administrator and the user SYSTEM or +SYSTEM.  If you really
> want to check by SID, feel free to enumerate all accounts by just
> omitting the username and scan for the SID you're looking for:
> 
>   $ getent passwd | grep ',S-1-5-32-544:'
> 
>   $ getent group | grep ':S-1-5-18:'

Btw., the uids and gids are fixed values in the new model and they are
probably never changed by most users of /etc/passwd and /etc/group
either.  I think it's perfectly sensible to check for uid 18 when
looking for system, for instance:

  $ getent passwd 18
  +SYSTEM:*:18:18:U-NT AUTHORITY\SYSTEM,S-1-5-18:/home/SYSTEM:/bin/bash
  $ getent passwd 544
  +Administrators:*:544:513:U-BUILTIN\Administrators,S-1-5-32-544:/home/Administrators:/bin/bash


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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