How to get back Windows on the grub menu?

[Liam Proven]

On Wed, 27 Oct 2021 at 15:50, Bo Berglund <bo.berglund at gmail.com> wrote:
>
> I am not running the desktop version of ubuntu so I cannot use gparted to see
> the disk. Instead I used fdisk:

Looks like just 1 ESP. Good!

> >It is mounted under `/boot/efi`?
>
> Not mounted as far as I can see:
> # mount | grep "/boot"
> returns nothing.

That is bad.

The ESP needs to be mounted onto the existing, hopefully empty, folder

/boot/efi

See here:
https://superuser.com/questions/1430485/ubuntu-18-04-cannot-mount-boot-efi

> So should I just mount them like this temporarily:
> /mnt/win (nvme0n1p3)
> /mnt/desk (nvme0n1p5)

Anywhere you like, really, so long as the `os-prober` tool can see them.

> Is the idea to then issue:
> # update-grub

Yes, that's correct.

> I have searched a lot to get to the state I posted earlier where I now have a
> really awkward method to switch between two different grub boot menus.

You have 2 different GRUB menus on the hard disk? (Not counting
bootable USBs etc.)

> So in order to boot off USB attached media I have to go through a big loop to be
> able to launch Windows and from there special key presses to get to a boot media
> selection menu where I finally can boot to the live media...

Welcome to the "improved" world of UEFI. :-(

> The desktop was installed here from live media when I was able to do this
> easily. So its installer should have seen the EFI/UEFI stuff.

Ideally use this version to manage GRUB.

> My fear now is that by doing anything to GRUB I might destroy the possibility to
> actually do the workaround and am stuck with a system that cannot be backed up
> fully...

Well, you can back up the ESP like any other partition...

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