====== GRUB ======
**__GR__and __U__nified __B__ootloader** (GRUB) is a common boot tool used in Linux distros. It handles loading Linux and other operating systems.

===== Installation =====

==== Re-installation ====

I've come across hard disk trouble a few times that were solved by reinstalling GRUB. For example on booting getting a GRUB prompt with a ''no such partition'' error.

This has typically had to be done via booting with the [[arch_linux]] install USB because it was impossible to boot otherwise. The process is the same as the initial install.

The process is:

  - Boot into the Arch install environment (make sure you're in UEFI mode if your computer supports it. All the following instructions assume UEFI)
  - Use ''lsblk'' to get locations of disks.
  - Mount those under ''/mnt'' /mnt/home'' ''/mnt/efi'' as applicable.
  - Use ''arch-chroot'' to get into the mounted stuff and [[archw>GRUB#Installation_2|install GRUB as normal]], eg:
    - ''grub-install --target=x86_64-efi --efi-directory=/efi --bootloader-id=GRUB''
    - ''grub-mkconfig -o /boot/grub/grub.cfg''
  - Reboot, cross your fingers.

{{tag>fixes grub guide linux software}}