I have been running OpenSuSe Tumbleweed for a couple years now.


A week ago, the machine changed behaviour. Now it does not boot the OS, I just get a Grub prompt.


I have an external USB DVD drive.


How do I force GRUB to boot the DVD and reinstall the OS ??


I'm looking for the command.


Thanks for any help you can give me. I'm stuck :-)


Pete

Did you do something that warrants a re-install? If not you should be able to recover from the grub prompt.
this tell how to boot from grub prompt, not sure if opensuse uses /boot/grub or /boot/grub2, here are two how tos to recover from grub prompt and fix
https://help.ubuntu.com/community/Grub2/Troubleshooting
https://www.linux.com/training-tutor...-grub-2-linux/

You shouldn't need to reinstall just because Grub isn't working right any more. You should be able to boot the installation media by hitting a hotkey before POST completes. That key varies by manufacturer. My own hotkey list:From a grub> prompt it's possible to boot if you have a copy of grub.cfg or menu.lst saved since the current partitioning was implemented to use as template. menu.lst is nothing but commands that can be used at a Grub shell prompt. Grub.cfg is rather more complicated, but functions basically the same. It's possible to type in the skeletal versions of those commands to get the installed system booted, after which you can run Yast to reconfigure the bootloader, by no more change than to add or remove a second from the timeout value.

If you have no available copies of grub.cfg, look here to see some examples of minimalist stanzas that can function as templates. If you don't have labels on your partitions, you can make some before proceeding using e2label or tune2fs -L, or use device names or UUIDs instead. LABELs are convenient because they can be quite short, and easy for you, presumably a human, to remember and type without error.

Here's a bare minimum example for booting from the #2 partition on the first disk (which is normally mounted to /boot):

Grub does neither of these things:

• the BIOS decides which device the machine tries to boot from. Often there's a "Boot Selection" hotkey you can press during early boot.
  
• the booted device might start an installer or a live environment
  

I'd ask why you wish to try to get bios to boot to usb dvd.
Not sure what might happen but that is a non-standard way.
I'd boot to usb dvd from bios unless the system is really old and can't boot to usb. I used to boot to network cd to then boot to usb dvd.

Anyway. https://help.ubuntu.com/community/Bo...command%20mode.

Grub wouldn't be involved in booting from the optical drive; your system BIOS would have that as an option. Check in your BIOS if the system knows to boot from optical drive and that the boot order has the optical drive before the hard disk.

Once you get the system to boot a rescue system from the optical drive, you ought to be able to check the Grub configuration and make repairs to it. IMHO, it's premature to resort to re-installing Linux until you've exhausted the fix Grub option. Also, I'd be leery of re-installing unless you've partitioned the hard disk in such a way that allowed you to separate your personal data from the OS. If you haven't, booting from the optical drive to a rescue system would allow you to backup your personal data -- and any configuration files in /etc you may have made changes to -- before resorting to a re-installation.

HTH...