My brother's PC has a 128Gb SSD that originally contained just one copy of Mint 20 (which I'll call "OLDmint").

I booted from a "Live" Mint installation USB memory stick and used the Disks utility to "shrink" the original partition to 40Gb. Then I installed a second copy of Mint 20 (which I'll call "NEWmint") alongside OLDmint.

Everything works as expected except it always boots by default into NEWmint, which I don't seem to be able to change.

I used Software Manager (within NEWmint) to install Grub Customiser, then used that to delete the unwanted "Advanced Options" and move the OLDmint boot option up to the top of the list so as to make that the default.

But that Grub menu change made within NEWmint isn't reflected in the boot options. I installed Grub Customiser on OLDmint and tried to run it, but all options seem to be greyed out (and the display doesn't show thereflect changes made under NEWmint). I also ran sudo update-grub from the command line, but that made no difference.

I don't really understand UEFI. The PC bios has both UEFI and "non-UEFI" boot options for the SSD, but changing this makes no difference. I think those same (UEFI Y/N) options were available when booting from the Mint Live USB memory stick to install NEWmint, but I can't remember which I chose.

I could probably resolve this problem if I had my brother's PC in front of me. But he's hundreds of miles away, very "non-technical", and only available for (voice-only) telephone support sporadically. It's taken a long time to get as far as we have.

The reason I want this second copy of Mint is simply so my brother can override the Grub default periodically (using Down Arrow) to boot into NEWmint and use fsarchiver for system backups. That's how my own PC is set up, and I find it really easy to use. My "NEWmint" is only normally used to run the same single backup command every time, so I just open a Terminal, Up Arrow to the previous command, re-execute it, then boot back into my normal system.

Live / OLD / NEW Mint above are all Version 20. I think I had some kind of issue relating to Grub Customiser under latest Mint21 when I upgraded my own PC a couple of months ago. But whatever it was (I've forgotten - maybe it wasn't originally in the repository) I obviously got around that problem. I think it was entirely to do with Mint 21, though, so it's probably irrelevant.

How can I ensure my Grub menu changes are reflected in all other copies of Linux on the same machine (and by the actual boot process! :)

  • I have multiple Ubuntu installs. Last install is normally grub that is in control of booting. All system must be installed in UEFI mode, if one system is UEFI. Grub Customizer replaces all of grub's scripts with proxy files. Do not really know those as I just modify grub myself. You should be able to boot into OLDmint & do a sudo grub-install. That will make it default. But a major grub update in NEWmint may do that and make it first. How to: Create a Customized GRUB2 Screen that is Maintenance Free.- Cavsfan help.ubuntu.com/community/MaintenanceFreeCustomGrub2Screen
    – oldfred
    Oct 13 at 14:21
  • I think by that you mean if I execute command sudo grub-install (rather than sudo update-grub as mentioned above), things might work the way I want. Note that I don't expect to perform any updates to NEWmint once it's installed and working. I have two PCs set up like this myself - on one of them I just ignore any messages about system updates, and the other one doesn't even have an internet connection anyway (it's wifi, and I never configured my wifi password). So long as they can run the installed copy of fsarchiver (which I don't care about updating) that's all I want it to do. Oct 13 at 14:28
  • 1
    If I remember correctly (I haven't done this in a while) you need both sudo update-grub which is just a little shell wrapper for grub-mkconfig which will make the changes to the grub configuration and sudo grub-install /dev/XXX where /dev/XXX is the partition you install to. The latter will actually install your changed menu. Does that work?
    – terdon
    Oct 13 at 14:35
  • @terdon: ty for response. From what I recall, OLDmint was installed on /dev/sda1, and NEWmint is on a newly-created partition /dev/sda2 (I can get my brother to check that from MainMenu > Accessories > Disks when he's next available). Are you saying I should get him to execute sudo update-grub BEFORE sudo grub-install, or is it the other way round? Oct 13 at 14:42
  • 1
    Other way around: first update, then install. See How can I fix/install/reinstall grub?
    – terdon
    Oct 13 at 14:48

1 Answer 1


I don't really understand why this worked, but thanks to comments provided by @terdon under the question, I got my brother to break into the Grub menu using Down Arrow to select and boot into OLDmint, and run these two commands...

sudo update-grub

sudo grub-install

...after which the system boots by default into OLDmint. And the menu that Grub Customiser provides edit facilities for is the same regardless of whether I run it from OLDmint or NEWmint (the unwanted "Advanced Options" have all disappeared).

It may be that this method won't continue to work if/when system updates are applied to NEWmint. But that doesn't matter to me because I don't need to update that system anyway. Since it's only there to run fsarchiver, NEWmint doesn't even need to access the Internet at all.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.