2

I have installed Linux Mint besides Lubuntu on my pc.

Since then, my computer boots to Mint's custom GRUB, instead of Lubuntu's GRUB. Lubuntu still updates its bootloader every time apt installs a new kernel, but it doesn't make this bootloader appear anywhere.

I prefer the old GRUB (mainly because it automatically boots Lubuntu). How do I make it default again?

אברהם צבאן
  • 43
  • @user535733 gone wont make any further comments. – David Apr 11 '21 at 14:35
  • 1
    UEFI or BIOS? You can do the reinstall, not update of grub from Lubuntu and that will reset it. But each install with major update of grub resets boot. If BIOS you want Lubuntu's grub in MBR. If UEFI you want Lubuntu's grub in /EFI/ubuntu folder. You can also manually edit /EFI/ubuntu/grub.cfg with correct UUID/partition info. Its only 3 lines long as configfile to load the full grub in your install. More info on UEFI: https://askubuntu.com/questions/792413/how-to-set-grub-from-second-linux-distribution-as-default-in-uefi-boot – oldfred Apr 11 '21 at 15:04

2 Answers2

2

You haven't provided specifics as to your box - are you using uEFI, Secure uEFI or BIOS in booting? I'll assume BIOS and walk through a common process I do.

For my own boxes (where I QA-test and install releases many times per week) and often have 1-6 (GNU/Linux but mostly Ubuntu flavors) systems installed on a box, the last installed will always end up owning the grub and after validating all is good with the last QA-test install (& reporting the test on iso.qa.ubu.com...),

I boot the system I want to own grub and

sudo update-grub
sudo grub-install /dev/sda

I use the first update-grub command so it's made aware of my last install and any changes (say a Lubuntu hirsute daily which may have a later kernel than the prior install present). Secondly I make that OS take ownership of the MBR (master boot record) of the disk the BIOS system boots (in this example it's my Debian Bullseye/sid; I don't test on my primary system which runs Lubuntu).

I've assumed BIOS for this, following steps I do very regularly on one box in particular but adjust for your specific box; on some it won't be /dev/sda

guiverc
  • 30,396
0

The classic answer for most users:

  1. Login to your Lubuntu system.
  2. Run sudo update-grub

Here's a more complex answer, transferring menu items from one to the other. However, the answer is a bit stale so I'll update it here:

  • Look for /boot/grub/grub.cfg on both OS. Copy them to a place where you can see both side-by-side.
  • At the bottom of each grub.cfg file are the menu settings. If there is a particular menu setting missing from one, DON'T copy it across.
  • Look in /etc/grub.d/ on both OS. Find the file that creates the missing menu setting. Copy that file across.
  • Finally, run sudo update-grub to create a new grub.cfg file with the new settings.

Some folks install a different OS on each disk, which likely means those folks have two GRUBs installed, one on each disk.

  • This ONLY applies to different disks. If you have two partition on the same disk, then top. This won't help you.
  • You can simply select which disk to boot in BIOS.
  • You can use the previous instructions to copy one menu item across to the other GRUB. You must make sure the menu item points to the correct disk.
  • Or you can completely overwrite one of the GRUBs with grub-install /dev/sdX (obviously you must replace X with the correct disk.
user535733
  • 62,253
  • Updating grub is helpless; both machines update their grub frequently, but it does not change bootloader priorities. The second solution is also related to other questions. I will look into the third answer later. Thanks – אברהם צבאן Apr 11 '21 at 15:56