Re: How does one add a second Ubuntu installation to an existing one?

[Chris Green]

On Fri, May 21, 2021 at 01:10:27PM +0200, Pascal Hambourg wrote:
> Le 21/05/2021 à 10:24, Chris Green a écrit :
> > 
> > How should I do the changes to /boot/grub/grub.cfg?  Do I edit
> > /etc/default/grub and then run grub-mkconfig?  However I don't really
> > see how this would work, I can set the output file for grub-mkconfig
> > but how do I tell it to use the /etc/default/grub in /dev/sdc1?
> 
> You can either run grub-mkconfig or edit /boot/grub/grub.cfg manually.
> If you choose to use grub-mkconfig, you must run in while /dev/sdc1 is the
> root, either by booting it or by chrooting into it from the original system.
> 
> > At what stage does the copy in /dev/sdc1 get added to my boot menu?
> 
> After you run update-grub or grub-mkconfig in the original OS.
> 
> > > I would also install GRUB on /dev/sdc from the copy to be able to boot if
> > > the original installation is so broken that even GRUB does not work any
> > > more.
> > > 
> > Definitely, is that just a matter of booting the copy OS and running
> > grub-install?
> 
> You don't even need to boot (or chroot) into the copy OS. You can run
> 
> # grub-install --boot-directory=/mnt /dev/sdc
> 
> in the original OS.
> 
Thank you, that's really helpful.  :-)

-- 
Chris Green