grub – ServerOK

RHEL Based – AlmaLinux, CentOS, RockeyLinux, Oracle Linux

Regenerate grub config

grub2-mkconfig -o /boot/grub2/grub.cfg
grub2-mkconfig -o /boot/efi/EFI/centos/grub.cfg
grub2-mkconfig -o /boot/efi/EFI/almalinux/grub.cfg

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

grub2-mkconfig -o /boot/efi/EFI/centos/grub.cfg

grub2-mkconfig -o /boot/efi/EFI/almalinux/grub.cfg

grub config on RHEL

/etc/default/grub

1	/etc/default/grub

To install Grub, run

/sbin/grub2-install /dev/sda

1	/sbin/grub2-install /dev/sda

To see all available kernels

awk -F\' '$1=="menuentry " {print i++ " =  "$2}' /etc/grub2.cfg

1	awk -F\' '$1=="menuentry " {print i++ " = "$2}' /etc/grub2.cfg

If all kernels not showing, edit

vi /etc/default/grub

1	vi /etc/default/grub

Add

GRUB_DISABLE_SUBMENU=true
GRUB_DEFAULT=saved

1 2	GRUB_DISABLE_SUBMENU=true GRUB_DEFAULT=saved

Rebuild grub

grub2-mkconfig -o /etc/grub2.cfg

1	grub2-mkconfig -o /etc/grub2.cfg

To set default Kernel

grub2-set-default 0

1	grub2-set-default 0

To see the current Kernel

grub2-editenv list

1	grub2-editenv list

Reinstall kernel and set it to default

yum reinstall kernel
grub2-set-default 0
grubby --set-default 0

yum reinstall kernel

grub2-set-default 0

grubby --set-default 0

sudo update-grub
/usr/sbin/grub-mkconfig -o /boot/grub/grub.cfg

1 2	sudo update-grub /usr/sbin/grub-mkconfig -o /boot/grub/grub.cfg