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I have three Linux installs and one Windows 8.1 install on my computer. Now, I've only installed Grub2 on one Linux install. So, I always have to login to that one to use update-grub. The problem is, I want to get rid of exactly that Linux install.

So, my goal is it to get it to work, that I can use update-grub from another install, while keeping the grub installation, that is sitting on my EFI partition.

The install that should be the one for updating grub2 from now on is Arch.

Is this somehow possible and if how?

  • I'm not quite sure I have understood your question. Do you have three different distros in your HD and you can boot choosing what distro you want to start with or you have only one? – YoMismo Oct 23 '14 at 6:51
  • Do you have a separate boot partition? Also is rEFInd an option? – DarkSheep Oct 23 '14 at 15:13
  • I have 3 different distros and one Win install. I can choose in which one to boot at startup thanks to Grub. Well, at least it was that way, now it seems I messed up. – fluxkompensator Oct 24 '14 at 1:00
  • Yes, I have a separate EFI partition. I don't know, what rEFInd is. – fluxkompensator Oct 24 '14 at 1:01
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Your bootsector uses the files under /boot and that then uses /boot/grub/grub.cfg for further menu selection.

Before you do anything make sure you have a bootable CD/USB, in case you make your system unbootable. It is much more easy to make the CD/USB before you break anything. And try it out.

The next thing to do is boot from one of the other Linux installed on your system and do:

sudo update-grub

and inspect the resulting /boot/grub/grub.cfg, to make sure the three Linux installs are in there as well as the Windows8.1 one. You will notice that the currently booted Linux will be the default in the menu.

Now you can have the boot sector point to this Linux. Assuming you boot from /dev/sda:

grub-install /dev/sda

This is IMO the simplest way to do this as there is no need to chroot. Of course it relies on a bootable installation already being available.

  • I've seem to have done something wrong here. Now, Grub is somehow gone and my laptop just boots into Win 8.1 at startup. Will report back tomorrow with results from Live CD. – fluxkompensator Oct 24 '14 at 1:05
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You have to boot from another Live or installed linux, Then chroot to the given linux(you wan t to install its grub)
Then you have to apply:

grub-install /dev/YOURDEV

such as:

grub-install /dev/sda

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