Re: [PATCH] grub-shell: Only show grub-mkrescue output if it returns an error

[Daniel Kiper]

On Thu, Aug 11, 2022 at 12:06:43PM -0500, Glenn Washburn wrote:
> The previous behavior ignored an error and the output from grub-mkrescue.
> This made it difficult to discover that grub-mkrescue was the reason that
> tests which rely on grub-shell were failing. Even after discovering
> grub-mkrescue was the culprit, there was no output to indicate why it was
> failing. It turns out that grub-mkrescue is a thin wrapper around xorriso.
> So if you do not have xorriso installed it will fail with an error message
> about not being able to find xorriso.
>
> This change will allow grub-mkrescue output to be written to stderr, only
> if grub-mkrescue fails. If grub-mkrescue succeeds, there will be no output
> from grub-mkrescue so as not to interfere with the functioning of tests.
> This change should have no effect on the running of tests or other uses of
> grub-shell as it only modifies the error path.
>
> Also, if grub-mkrescue fails, the script exits early. Since grub-shell
> needs the iso image created by grub-mkresue to boot the QEMU instance, a
> failure here should be considered fatal.
>
> Signed-off-by: Glenn Washburn <development@efficientek.com>

This completely breaks messages formatting, especially multi-line ones,
but is better than silent error.

So, Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>...

Daniel