On Fri, 11 Jun 2021 21:38:37 +0300 Semih Ozlem <semihozlemlinuxu...@gmail.com> wrote:
> I reinstalled the system, including an efi partition (500MiB) and the > problem was fixed. > > How to check where grub is installed? And what is a friendly guide to > learning about grub? I don't like quoting specific sources, as they go out of date so quickly, but here's the official starting point: https://www.gnu.org/software/grub/ There is a lot of other information on the Net, some of it more user-friendly, but much of it is out of date. Search using the version number of grub, which you see on the boot menu screen, and use 'grub2' which is the current package name. Grub lives in more than one place: most of it is in /boot/grub, but there is a first-stage bootloader which calls this. To be honest, I don't know for sure where that lives on a GPT disk, on the old DOS-type partition it would live at the start of either the whole hard drive or the start of a particular partition, chosen during installation. I'm guessing it's the same for GPT partitioning. With an EFI system there is more to it that, you've already found the need for an /efi partition/folder, but there's also an EFI boot table on the drive, and something else which tells the computer where to look for entries. I have a netbook which booted fine into grub on stretch, but an upgrade to buster killed that, and to boot into buster I have to use a rescue medium and use efibootmgr to set NextBoot to the right entry. Nobody here seems able to help, and I gave Google a good kicking to no avail. Clearly you don't have this problem. -- Joe
