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I have installed first Kubuntu (sda3), then installed Ubuntu (sda4) and finally Linux Mint (sda5) on the same SSD (back to back). I want to remove Linux Mint from the disk and from the grub menu. But since I have installed Linux Mint as final, grub customization works only on Mint.

I plan to remove sda5 partition but I am afraid if I lose the grub menu. How can I safely remove Linux Mint (sda5) and get control of the grub menu to Ubuntu (sda4)?

Thank you in advance.

deeptionary
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    Make sure one OS you're going to keep owns the boot process (`grub-install /dev/sda` for example to make it take ownership), then from that OS remove the unwanted partition & you're done. If the first step is missed (making another OS own boot process), you'll end up with *grub rescue* as the Mint's grub is broken, so have whichever you want to own the process take over boot (make it's grub active). – guiverc Apr 29 '21 at 17:53
  • So to make "ubuntu" own boot process (which is in sda4) should I run the command "sudo grub-install /dev/sda4"? and after that, I remove the mint partition on ubuntu? – deeptionary Apr 29 '21 at 17:58
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    You can boot to a live session and use OS uninstaller. https://askubuntu.com/a/167785/124466 – Archisman Panigrahi Apr 29 '21 at 18:06
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    You don't install grub to a partition, but to the device. ie. your command will not help, you need to use `/dev/sda` as per my comment, as the MBR is the first 512 bytes (first sector) of the drive; it's reserved for that purpose, and there is only one (regardless of how many partitions you have; it's before them). The `grub-install` command just installs the MBR into place.. `update-grub` can be used after removing the Mint partition to have it re-scan, notice Mint is gone & have correct menu options (grub menu is stored in /boot/grub/) but that'll occur on next kernel upgrade anyway... – guiverc Apr 29 '21 at 18:15

1 Answers1

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Boot into Ubuntu, reinstall grub (maybe sudo update-grub is enough), remove the Linux Mint partition and run sudo update-grub.

Also, don't worry. Just make a Live USB before doing any change. You will always be able to set things straight again, in one of the bad cases by doing a so called chroot. I would actually encourage you to fail and try to fix it, you will learn a lot.

alexg2021
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