[lug] How to boot from another HD?

[Zan Lynx]

On 9/26/2020 4:39 PM, Michael Hirsch wrote:
> My desktop computer died, so I bought a Dell 3880.  Installed ubuntu
> (kubuntu, actually) 20.04.1 on the SSD.  Then I brought my 1TB drive
> over from the dead computer and mounted it at /home and all my files
> are back.  Yay!
> 
> Actually, a bunch of stuff isn't working as expected, so I thought I'd
> try running my old OS.  I put the SSD from my dead system in my new
> computer.
> 
> I can see the drive, but for the life of me I can't figure out how to
> set things up to boot from it.
> 
> I used to be a master of editing lilo or grub files, but it has
> changed in the last 10 or more years, not to mention "secure boot"
> which scares me, but seems to work.
> 
> Can someone point me to a tutorial, or talk me through booting to this
> alternate hard drive?

There's a couple of ways to do this.

You can change the boot in the BIOS to point to the original SSD. You'd 
have to switch which one you boot using your BIOS boot select (F12 on mine).

Or you can add the old drive to the new drive's GRUB entries. I honestly 
don't know how Ubuntu does GRUB management. I used to know Debian but 
that was like, 2005 and I'm sure they changed it.

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