[bug#29409] [PATCH v2 3/4] scripts: system: Add --expression option.

[ludo@gnu.org (Ludovic Courtès)]

m.othacehe@gmail.com skribis:

> From: Mathieu Othacehe <m.othacehe@gmail.com>
>
> * guix/scripts/system.scm (show-help): Add expression option.
> (%options): Ditto.
> (process-action): Read operating-system from expression or file.
> * Makefile.am (release): Use expression instead of file to produce
> disk-images.
> * doc/guix.texi (Building the Installation Image): Adapt disk-image command to
>   use an expression.
> (Invoking guix system): Introduce the expression option.
> ---
>  Makefile.am             |  2 +-
>  doc/guix.texi           | 10 +++++++++-
>  guix/scripts/system.scm | 24 +++++++++++++++++++-----
>  3 files changed, 29 insertions(+), 7 deletions(-)
>
> diff --git a/Makefile.am b/Makefile.am
> index 85b9ab3..dff1e5e 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -648,7 +648,7 @@ release: dist
>  	    guix system disk-image							\
>  	    --file-system-type=iso9660							\
>              --system=$$system								\
> -	    gnu/system/install.scm` ;							\
> +	    -e "(@ (gnu system install) installation-os)"` ;							\

[...]

>  @example
> -guix system disk-image gnu/system/install.scm
> +guix system disk-image -e "(@@ (gnu system install) installation-os)"
>  @end example

I’d suggest leaving these two things unchanged because it’s still more
convenient to type the file name.

>    (display (G_ "
> +  -e, --expression=EXPR  consider the operating-system EXPR evaluates to
                                                  ^
No hyphen.

[...]

>        (case action
>          ((build container vm vm-image disk-image reconfigure)
> -         (unless (= count 1)
> +         (unless (or (= count 1) (= count 0))
>             (fail)))

What happens if we run “guix system vm”?  Do we still get a proper
error?

The rest LGTM.

Thanks,
Ludo’.