GRUB2

Kernel command line parameters passed in on boot can be queried during runtime:

cat /proc/cmdline

Tasks

Append rd.break to the list of command-line parameters to GRUB. Once the shell is ready, run the following commands

mount -o remount,rw /sysroot
chroot /sysroot
passwd root

RHEL can be installed from the console by providing inst.text as a kernel parameter on boot by pressing ++Tab++ on the GRUB splash screen.

When GRUB2 is unable to find the GRUB folder or its contents are missing or corrupted, it displays the prompt

grub rescue>

This means it failed to load the normal module. howtoforge.com

From GRUB rescue prompt:

set prefix=(hd0,1)/boot/grub
set root=(hd0,1)
insmod normal
normal

After booting the system, GRUB should be updated and reinstalled:

Update GRUB config file

update-grub

Reinstall GRUB

grub-install /dev/sdx

Generate GRUB configuration

grub-mkconfig -o /boot/grub/grub.cfg

grub2-mkconfig is used to create a GRUB2 config file from the settings defined in /etc/default/grub

grub2-mkconfig -o=/boot/grub2/grub.cfg

Disable the Nouveau display driver while installing the proprietary Nvidia display driver on Fedora

grub2-editenv - set "$(grub2-editenv - list | grep kernelopts) nouveau.modeset=0"

Update GRUB config file

update-grub