Re: User accounts

[Ludovic Courtès]

John Darrington <address@hidden> skribis:

> On Tue, May 13, 2014 at 10:11:41AM +0200, Ludovic Court??s wrote:
>      Before commit ab6a279, /etc/{group,passwd,shadow} were all created from
>      a derivation.  Thus, /etc contained symlinks to those files, which were
>      actually in the store.  Being in the store, they were all immutable and
>      world-readable (you can see that in the VM image released with 0.6.)
>      
>      That was obviously not desirable, because then everyone can read shadow,
>      and because that prevents passwords from being changed.
>      
>      So commit ab6a279 changed accounts to be created at ???activation
>      time??????i.e., when booting, or when switching to a new operating system
>      configuration.  What happens is that the activation code checks for all
>      the user accounts and groups required by the ???operating-system???
>      declaration, and invokes ???useradd??? and ???groupadd??? for any missing
>      account/group.
>      
>      That way, {group,passwd,shadow} are normal state files with the right
>      permissions, and everything works as expected.  NixOS uses the same
>      strategy.
>      
>
> Does /etc/group now have a "nogroup" group?

No, but it’d be a useful addition.

> I was trying to package up GNU cssc, but one of its tests relies on
> having a group which no user is a member of.

Ah, but that’s a different story: you’re referring to the build
environment, whereas I was talking about the operating system
declarative configuration, for use in the stand-alone system (info
"(guix) System Configuration").

Regarding the build environment, maybe it makes sense to add ‘nogroup’
as well; not completely sure.  Any pointers as to how ubiquitous it is,
or other arguments?

Ludo’.