A question about multiple boot options and live boot iso images

[Brian]

On Wed 30 Oct 2019 at 21:09:50 +0000, Bret Busby wrote:

> On 30/10/2019, Liam Proven <lproven at gmail.com> wrote:
> > On Wed, 30 Oct 2019 at 17:44, Colin Law <clanlaw at gmail.com> wrote:
> >>
> >> Will the installer allow one to install onto a USB stick?  If so then
> >> maybe you can install in the same way you would if it were an internal
> >> disk.
> >
> > To be perfectly honest I did not understand Brett's huge multiline
> > sentence, so I am not sure what his question was.
> >
> > No, AFAIK, the Ubuntu installer won't let you install directly onto
> > removable media.
> >
> > However, you can attach a USB key directly to a virtual machine and
> > then *as far as that VM is concerned* it is a hard disk, the only one
> > in the computer, and you can install.
> >
> 
> I am not seeking to install to a removable USB drive.
> 
> I am seeking to be able to write/copy multiple iso's to a removable
> USB drive, and, thence to be able, via a bootloader, such as GRUB, to
> select which iso on the removable USB drive, to boot.

1. Make a partition on the drive to hold GRUB's files and install GRUB
   to the MBR of the drive.

2. Make a partition large enough to contain a chosen ISO and cat or dd
   the ISO to it.

3. Obtain the second partition's label with 'lsblkid -o list'.

4. Open the ISO and determine what is needed for the linux and initrd
   lines in a grub.cfg. Critical, and not always as easy as it sounds.

5. Construct a grub.cfg file to put in the grub directory on the first
   partition. A working example:

    set menu_color_normal=white/black
    set menu_color_highlight=white/green
    menuentry "Debian GNU/Linux Live (Cinnamon)" {
    search --label --set=root "d-live 10.1.0 ci amd64"
         linux /live/vmlinuz-4.19.0-6-amd64 boot=live components splash quiet
         initrd /live/initrd.img-4.19.0-6-amd64
    }
6. Repeat for other ISOs.

-- 
Brian.