What happens if I invoke “zypper update” and don’t have grub2 installed and I have locked it out? I realize I have to edit whatever bootloader I do use, but does zypper complete and leave me with a non bootable system. Would I have to boot a live USB and modify whatever bootloader I use or would I have a dead system?
I have 3 systems on my computer but only one of them has a bootloader (grub2). I’ve never had a problem with updates although I do have to amend grub.cfg fairly frequently.
Most updates don’t affect booting.
Some do, such as installing a new kernel.
When an update affects booting, the command “update-bootloader” is automatically run. That still supports grub legacy and probably lilo.
If you have installed your own unsupported “weird-bootloader”, then you probably need to update that yourself.
If the kernel is updated, but somehow the bootloader is not updated, the chances are that the system will still boot. But it will boot the previous kernel. (If you have turned of multi-version kernel support, your system will probably be unbootable in that case).
Yes, but /etc/sysconfig/bootloader (LOADER_TYPE) needs to be set accordingly.
YaST only offers the choice between “grub2” and “none” nowadays, if you enter YaST->Boot Loader and press OK, it will set it to one of those.
I’m not sure which other ones are still supported, and to what degree.
Depending on your use-case, “none” may be the best choice anyway (e.g. if you have one bootloader for multiple installations).
It means that the bootloader config will not be touched at all.
I’m not sure if it would work in other distros but I keep a net install usb of the main system and on a couple of occasions I’ve lost boot (not for the reasons you raised). If it happens I load the usb and do an upgrade. You can keep all the repos you already use, stop it from updating anything and reinstall grub (it may work for other bootloaders if it’s in one of your repos).