Re: Unable to find wireless printer/scanner (Canon Pixma MG2950) on Guix.

[Gary Johnson]

Hi Luigi,

  If you need to edit files under /etc, the first place to look is in
the configuration settings for the service you expect to read/write
those files.

  However, if those settings don't exist, a possible fallback is to use
Guix's `etc-service`.

```scheme
(use-modules ((gnu services) #:select (etc-service))
             ((guix gexp)    #:select (plain-file)))

(define my-resolv.conf "nameserver 192.168.foo.bar")

...
(operating-system
 ...
 (services (cons*
            ;; Add files under /etc
            (etc-service `(("resolv.conf" ,(plain-file "resolv.conf" 
my-resolv.conf)))))))
```

Happy hacking!
  Gary

Luigi Salamone <lg.salamone@gmail.com> writes:

> Thanks!
>
> Yes, I have '(name-service-switch %mdns-host-lookup-nss)' in my
> /etc/config.scm.
>
> Now...as for the scanner:
> On Parabola I need to edit the file /etc/sane/pixma.conf (not present in
> Guix) to add such a line: bjnp://MyPixmaPrinter.local. See
> https://wiki.archlinux.org/title/SANE/Scanner-specific_problems#Canon
> I also edit the file /etc/nsswitch.conf as indicated here:
> https://wiki.archlinux.org/title/Avahi#Using_Avahi.
>
> As for the printer:
> I need the gutenprint drivers, which are not packaged for Guix. I've seen a
> patch for this: https://issues.guix.gnu.org/45725
> But unfortunately I have no idea which file to patch.
>
> Greetings!
> Luigi
>
> On Sat, Mar 11, 2023 at 8:55 AM Guillaume Le Vaillant <glv@posteo.net>
> wrote:
>
>> Luigi Salamone <lg.salamone@gmail.com> skribis:
>>
>> > Hi!
>> >
>> > My Canon Pixma MG2950 works fine on Parabola, after configuring avahi
>> with
>> > nss-mdns. But on Guix I can't find neither the printer nor the scanner.
>> > Tried with "system-config-printer" and via "lpinfo". What can I do? Here
>> > the salient lines of my /etc/config.scm:
>> >
>> > ...
>> > (use-package-modules cups scanner)
>> > ....
>> >
>> >  (packages (append (list (specification->package "cups")
>> >                          (specification->package "cups-filters")
>> >                          (specification->package "cups-filters")
>> >                          (specification->package "cups-pk-helper")
>> >                          (specification->package "foomatic-filters")
>> >                          (specification->package "ghostscript")
>> >                          (specification->package "sane-backends")
>> >                          (specification->package "simple-scan")
>> >                          (specification->package "nss-mdns")
>> >                          (specification->package "avahi")
>> > ....
>> > (services
>> >   (const* (service cups-service-type
>> >                     (cups-configuration
>> >                       (extensions
>> >                         (list cups-filters foomatic-filters hplip))
>> >                       (web-interface? #t)
>> >                       (default-paper-size "A4")))
>> >      (modify-services %desktop-services
>> >                         (sane-service-type _ =>
>> >                                            sane-backends)
>> >
>> > Thanks!
>> >
>> > Luigi
>>
>> Hi,
>>
>> Did you put '(name-service-switch %mdns-host-lookup-nss)' in your
>> 'operating-system' definition to activate name resolution using mDNS?
>>
>> There's a chapter about it in the manual:
>> https://guix.gnu.org/manual/en/html_node/Name-Service-Switch.html
>>


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