Running a shell command with home-run-on-change-service-type

Running a shell command with home-run-on-change-service-type

[Elias Kueny]

Hello,

I'm trying to extend the home-run-on-change-service-type service to run the fish command "fisher update" when the file ~/.config/fish/fish_plugins changed, so that fisher plugins are installed or removed by guix home reconfigure.

My service definitions are:

> (define-module (modules shells)
>   #:use-module (guix gexp)
>   #:use-module (gnu packages)
>   #:use-module (gnu services)
>   #:use-module (gnu home services)
>   #:use-module (gnu home services shells))
>
> (define-public fish-services
> 	       (list
> 		(simple-service 'fisher-update-on-change
> 				home-run-on-change-service-type
> 				`(("files/.config/fish/fish_plugins"
> 				   #~(system* #$(file-append fish "/bin/fish") "-c" "fisher update"))))
>
> 		(simple-service 'fish-home-xdg-configuration-service
> 				home-xdg-configuration-files-service-type
> 				`(("fish/fish_plugins"
> 				   ,(local-file "../config/fish/fish_plugins"))))))

The file change is detected on reconfigure, and then it throws an error: ice-9/boot-9.scm:1685:16: In procedure raise-exception: error: gexp: unbound variable (full backtrace below).
Could somebody tell me what is wrong with the G-expression? I don't understand which variable is unbound.

Backtrace:
> In guix/ui.scm:
>   2238:10 19 (run-guix-command _ . _)
> In ice-9/boot-9.scm:
>   1752:10 18 (with-exception-handler _ _ #:unwind? _ # _)
> In guix/status.scm:
>     835:3 17 (_)
>     815:4 16 (call-with-status-report _ _)
> In guix/scripts/home.scm:
>     513:4 15 (_)
> In ice-9/boot-9.scm:
>   1752:10 14 (with-exception-handler _ _ #:unwind? _ # _)
> In guix/store.scm:
>    661:37 13 (thunk)
>    1300:8 12 (call-with-build-handler _ _)
>    1300:8 11 (call-with-build-handler #<procedure 7f0af683c210 at g…> …)
>   2170:25 10 (run-with-store #<store-connection 256.99 7f0af90534b0> …)
> In guix/scripts/home.scm:
>    447:16  9 (_ _)
> In unknown file:
>            8 (primitive-load "/gnu/store/x8s6yhdzc79c1yfjwwwi4hq00s4…")
> In ice-9/eval.scm:
>     619:8  7 (_ #(#(#(#(#(#(#(#(#(#(#<…> …) …) …) …) …) …) …) …) …) …))
>     619:8  6 (_ #(#(#(#(#(#(#(#(#(#(#<…> …) …) …) …) …) …) …) …) …) …))
> In srfi/srfi-1.scm:
>     634:9  5 (for-each #<procedure primitive-eval (exp)> _)
> In ice-9/eval.scm:
>    191:27  4 (_ #f)
>    223:20  3 (proc #<directory (guile-user) 7f0b0f512c80>)
> In unknown file:
>            2 (%resolve-variable (7 . gexp) #<directory (guile-user) …>)
> In ice-9/boot-9.scm:
>   1685:16  1 (raise-exception _ #:continuable? _)
>   1685:16  0 (raise-exception _ #:continuable? _)
>
> ice-9/boot-9.scm:1685:16: In procedure raise-exception:
> error: gexp: unbound variable

Re: Running a shell command with home-run-on-change-service-type

[Jelle Licht]

Elias Kueny <elias.kueny@posteo.net> writes:

Hello Elias!

Buyer beware; I am not a G-expression guru. Having said that...

> Hello,
>
> I'm trying to extend the home-run-on-change-service-type service to run the fish command "fisher update" when the file ~/.config/fish/fish_plugins changed, so that fisher plugins are installed or removed by guix home reconfigure.
>
> My service definitions are:
>
>> (define-module (modules shells)
>>   #:use-module (guix gexp)
>>   #:use-module (gnu packages)
>>   #:use-module (gnu services)
>>   #:use-module (gnu home services)
>>   #:use-module (gnu home services shells))
>>
>> (define-public fish-services
>> 	       (list
>> 		(simple-service 'fisher-update-on-change
>> 				home-run-on-change-service-type
>> 				`(("files/.config/fish/fish_plugins"
>> 				   #~(system* #$(file-append fish "/bin/fish") "-c" "fisher update"))))

... here you quasi-quote the service extension configuration with
"`". To make use of a gexp in the expression, we need to unquote the gexp
expression, so replace "#~" by ",#~".

HTH and gets you unstuck!
- Jelle

Re: Running a shell command with home-run-on-change-service-type

[Elias Kueny]

On Tue, Dec 20 2022, Jelle Licht wrote:
> ... here you quasi-quote the service extension configuration with
> "`". To make use of a gexp in the expression, we need to unquote the gexp
> expression, so replace "#~" by ",#~".

Thank you, this was the solution!

I expected that replacing the quasi-quote by a normal quote would also do, but apparently no, as it gives the same error as before. And after I changed "#~" by ",#~" as you suggested, "#$(file-append fish "/bin/fish")" started throwing a different error.

But this now works so it's good enough for me:

>   (simple-service 'fisher-update-on-change
>		   home-run-on-change-service-type
>		   `(("files/.config/fish/fish_plugins"
>		      ,#~(system* "fish" "-c" "fisher update"))))