Christophe,

Christophe Pisteur 写道：
> Since now, I installed the following packages: cups, 
> cups-filters,
> fomatics-filters.
>
> When I launch http: // localhost: 631 / in my browser

So the important thing to (un)learn here is that installing Guix 
packages will never start random software in the background.  This 
is by design.

(Guix) System software is started by services that are part of 
your OPERATING-SYSTEM.  Here's part of my laptop's CUPS 
configuration:

  (use-service-modules ···
                       cups
                       ···)
  (operating-system
    (services
     (cons* ···
       (service cups-service-type
        (cups-configuration
         (extensions
          (list hplip-minimal
                ;; Required to display printer options,
                ;; even with IPP Everywhere everywhere.
                cups-filters
                ;; Other possible legacy drivers:
                ;; escpr foo2zjs foomatic-filters
                ;; hplip-minimal splix
                ))
         (server-name host-name)
         (host-name-lookups #t)
         (web-interface? #t)
         (default-paper-size "A4")
         ;; You get the idea.
         ···))
       ···
       %base-services-or-whatever)))

Adapt & add this to your system, run ‘sudo guix system 
reconfigure’, and you should be able to ‘herd start cups’ if it 
isn't automatically.  It will certainly be started at boot.

You should probably uninstall cups and the filter packages since 
they don't do what you thought they did, unless you want to keep 
them available in $PATH.

Kind regards,

T G-R