[xubuntu-users] dual boot - how to remove one OS

[Ralf Mardorf]

On Tue, 5 May 2015 18:47:17 -0700, Cody Smith wrote:
>Just make sure to run "sudo update-grub" or you'll (at best case) have
>an invalid entry, or at worst case totally bork grub.

This command does not repair a borked GRUB. It does generate a
grub.cfg, the menu list.

Speaking for good old BIOS and MBR based computers

sudo grub-install /dev/sdX

does reinstall GRUB, were X is for the partition, that usually should
be the first primary partition, of the first drive in the boot order,
not necessarily the partition were the grub.cfg etc. are installed.

"Repairing" grub is needed after resizing a partition, not when
"rm"/deleting a Linux install.

However, using MBR or not might be less important, but AFAIK using UEFI
might be an issue to consider.

There also is the question what Linux the OP wants to
sudo rm -rf /mountpoint/ /or_perhaps_mountpoints/ /mountpoints/
(that's the command needed to get rid or an unwanted Linux).

One of the two Linux installs does provide /boot/grub. The OP needs to
ensure to provide GRUB by the Linux that is kept.

JFTR removing the unneeded entry can also be done by using an editor,
e.g.

sudo nano /boot/grub/grub.cfg

Regards,
Ralf