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E.3. Installing GRUB

In a vast majority of cases, GRUB is installed and configured by default during the installation of Red Hat Enterprise Linux. However, if for some reason GRUB is not installed, or if you need to install it again, it is possible to install grub manually.
On systems without UEFI firmware, a valid GRUB configuration file must be present at /boot/grub/grub.conf. You can use the grub-install script (part of the grub package) to install GRUB. For example:
# grub-install disk
Replace disk with the device name of your system's boot drive such as /dev/sda.
On systems with UEFI firmware, a valid GRUB configuration file must be present at /boot/efi/EFI/redhat/grub.conf. An image of GRUB's first-stage boot loader is available on the EFI System Partitition in the directory EFI/redhat/ with the filename grubx64.efi, and you can use the efibootmgr command to install this image into your system's EFI System Partition. For example:
# efibootmgr -c -d disk -p partition_number -l /EFI/redhat/grubx64.efi -L "grub_uefi"
Replace disk with the name of the device containing the EFI System Partition (such as /dev/sda) and partition_number with the partition number of your EFI System Partition (the default value is 1, meaning the first partition on the disk).
For additional information about installing GRUB, see the GNU GRUB Manual and the grub-install(8) man page. For information about the EFI System Partition, see Section 9.18.1, “Advanced Boot Loader Configuration”. For information about the efibootmgr tool, see the efibootmgr(8) man page.