Stefan,

Stefan Huchler 写道：
> When I try to redefine the udev-service like described in [0]
[...]
> I get following error: /etc/config.scm: [...]

That's not what [0] describes, is it?  It illustrates some service 
concepts, using real code as example.

It doesn't imply that the example code can or should be added to a 
system configuration.

>> That module does not export udev-shepherd-service AFAICT.
> And which does,

Nobody: (gnu services base) defines udev-shepherd-service but does 
not export it.  It's not intended to be API, nor do I think it 
needs to be.

You might be able to use (@@ (gnu services base) 
udev-shepherd-service), which forces the module to give up its 
secrets.  It's not good style, and it won't always work but often 
does.

> and why does guix cli interface claim it would do that,
> with it's hint?

Because it's naive.  See <http://issues.guix.gnu.org/43498> and - 
please! - beat me to a fix ;-)

Kind regards,

T G-R

[0]: 
https://guix.gnu.org/manual/en/html_node/Service-Types-and-Services.html