[Utilities] Need help understanding grub-customizer

[Kumann]

When I have two distros installed, Kubuntu & Mint for example, grub-customizer in Mint shows both distros, but grub-customizer in Kubuntu shows only Kubuntu.
In grub-customizer there is a checkbox for searching for other distros, it is enabled in both grub-customizer on both distros.

Why are they different?

[oshunluvr]

Is Mint in the boot menu on Kubuntu?

If not, do you have os_prober enabled?

Which installation are you booting to? You can't boot to both unless you're using the BIOS to select which drive to boot to in a multi drive setup. Otherwise you're booting to one of them and choosing the other. The point is why do you need to customize both?

[claydoh]

My guess is that Kubuntu's grub needs to be updated to see any newly installed OS since the lat time it was updated, and that you have been using Mint's grub as the primary boot loader.

In Kubuntu, try running sudo update-grub in the terminal, and see if it helps.

Maybe there are differing version of the software between your Mint install and Kubuntu? This seems more like a bug in this third party application, maybe.

[Kumann]

Is Mint in the boot menu on Kubuntu?

If not, do you have os_prober enabled?

Which installation are you booting to? You can't boot to both unless you're using the BIOS to select which drive to boot to in a multi drive setup. Otherwise you're booting to one of them and choosing the other. The point is why do you need to customize both?

All is okay now.
I had to enable os_prober in the grub file.
Thanks!

[jlittle]

If you leave grub updating in both installs, they fight each other for control. This can cause trouble, such as losing customizations you've just made. I suggest either uninstalling one of the grubs, or changing to the -bin package (grub-efi-amd64-bin) that doesn't update automatically, or make a grub installation independent of the OS installs.

[Kumann]

If you leave grub updating in both installs, they fight each other for control. This can cause trouble, such as losing customizations you've just made. I suggest either uninstalling one of the grubs, or changing to the -bin package (grub-efi-amd64-bin) that doesn't update automatically, or make a grub installation independent of the OS installs.

Thanks for this post. It prevented me from screwing up two distros.
However I don't understand how to remove one of the grubs.
Is there a way to figure out which grub in which distro is actually the one used when booting?
Thanks in advance.

[claydoh]

Is there a way to figure out which grub in which distro is actually the one used when booting?

That is the one set in your bios settings' boot order - usually it is obvious which item is for which OS, but some BIOS can list things by partition and/or drive names.

[jlittle]

However I don't understand how to remove one of the grubs.

Uninstall grub-efi-amd64, but leave grub-efi-amd64-bin installed. It's a long time since I've sone such, and I worry that removing grub-efi-amd64 will take the rest of grub with it, as maybe they were installed as dependencies of the package you are removing; in theory, installing grub-efi-amd64-bin first will say something like "already at the latest version, marking as manually installed" and so not remove it.

Is there a way to figure out which grub in which distro is actually the one used when booting?

There's lots of ways. Applying different themes would be the most obvious, though I've never done that. An easy but temporary way would be editing grub.cfg to make a cosmetic change. You could edit /etc/default/grub to set GRUB_BACKGROUND to a jpg you copy to /boot/grub, though how that interacts with theming I don't know, and run update-grub. Without changing anything, you could type "c" on the grub menu then echo $root and ls and attempt to decipher grub's device naming scheme.

[Schwarzer Kater]

[…]
You could edit /etc/default/grub to set GRUB_BACKGROUND to a jpg you copy to /boot/grub, though how that interacts with theming I don't know, and run update-grub.
[…]

I think this would be the best of the three possibilities jlittle suggested.
You don't have to copy the image to /boot/grub/ (if you don't have a seperate partition for /boot, I think) - you can point to any image on the same partition.
The image is overwritten, if a theme (with a background image) is set in /etc/default/grub like GRUB_THEME="/path/to/your/theme" afaik.

The entry in /etc/default/grub for an image would be something like:
# Add background image to GRUB menu
GRUB_BACKGROUND="/usr/share/wallpapers/DarkestHour/contents/images/2560x1600.jpg"

You could open /etc/default/grub with Kate and just copy/paste the above example and save it, or use your own image of course.
But beware that this will only work in Kubuntu for sure in your case (aside from that the path to the image in my example is Kubuntu-specific) - probably not in LinuxMint as Mint handles GRUB a bit differently to apply their own theme and settings.
And as jlittle already wrote: Don't forget to sudo update-grub afterwards!

[Kumann]

Thanks to all. Before I futz with Grub I'll wait until I have a better understanding.

[oshunluvr]

Not speaking for everyone - but for most of us "futzing" is how we learned. You futz until it breaks, re-install, repeat. LOL

[Kumann]

oshunluvr, futzing (OJT) that's the I have always learned. Do it until death.