The way to set the /boot/grub/grub.cfg partition

BudiKusasi · 10-30-2021, 08:48 AM

How do we set which of the /boot/grub/grub.cfg partition which will run grub menu ?

ct7567 · 10-30-2021, 09:12 AM

can you explain more? you mean you have several linuxes and you want to use a grub from a specific one?

Brains · 11-01-2021, 10:50 AM

From the OS you want to have control over grub.cfg, you must reinstall grub efi and reconfigure grub. Then when you boot to the grub menu it will also be the first selection.

Ensure your EFI system partition is mounted, typically in /boot/efi.
In the example below, /dev/sda1 is the system partition, if you have nvme drive it will be something like /dev/nvme0n1p1

From your Debian based MX:

Code:

sudo mount /dev/sda1 /boot/efi
sudo apt-get install --reinstall grub-efi
sudo grub-install
sudo update-grub

mrmazda · 11-02-2021, 11:52 PM

If UEFI multi-booting, once you have the distro's Grub you wish to have in control of booting, confirmed by running efibootmgr, adjust the fstabs of the other distros to not mount any ESP partition. Thus configured, the other distros can be expected to not disturb your intended boot process. Of course, for this to work completely satisfactorily, you'll need to include the other distros in the controlling grub.cfg either via os-prober, or via either a /boot/grub[2]/custom.cfg or /etc/grub.d/.*CUSTOM.

yancek · 11-03-2021, 05:56 AM

Posts 3 and 4 give good information but the initial post was too cryptic and uninformative. A detailed answer to the question in post 2 would have been helpful in getting a more complete answer to the question, clarifying that the systems are UEFI would have been a first major step.

Quote:

How do we set which of the /boot/grub/grub.cfg partition which will run grub menu ?

Explaining the above would be useful as would ALWAYS indicating which of the 500+ Linux distibutions you might be using. They are most certainly not all identical. As pointed out above, IF you have decided and know which OS you want to handle Grub, it's a simple task as explained above on an EFI machine. It's a similar process for a Legacy install and this is something ALL Linux users to need to know where most computers sold currently are UEFI but some are Legacy/CSM. In a case where a windows OS is thrown in there are additional complications.

On Legacy Linux/CSM systems where you are using the MBR rather than EFI, user are told in scenarios such as this that the last Linux install will take over the boot for the particular machine. This is true but ONLY TRUE if the default device for bootloader installation is not changed. On dual/multi booting cases, it often is (or should be but the user isn't familiar with the process and by the time s/he finds out, a world of trouble lies ahead.