Table Of Content

Detect where grub is installed using debconf-show

$ sudo debconf-show grub-pc | grep -wi install_devices | awk -F: '{print $2}'

Detect where grub is installed using dd

# sudo dd bs=512 count=1 if=/dev/<device> 2>/dev/null | strings
$ sudo dd bs=512 count=1 if=/dev/sda 2>/dev/null | strings

Enable or disable grafical boot

This change is done in your default grub config file, open it and start editing

$ vim /etc/default/grub

to enable add splash in GRUB_CMDLINE_LINUX_DEFAULT, e.g like this:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pci=nomsi,noaer"

to disbale it remove splash

GRUB_CMDLINE_LINUX_DEFAULT="quiet pci=nomsi,noaer"

Grub EFI Rescureshell

Error EFI variables not supported

If you get the following error EFI variables are not supported on this system while updating/installing grub while you are in a rescue shell, it could be that the efivarfs module got not loaded.

To do so, run the following command:

$ modprobe efivarfs

If everthing is fine from that side, add rerun the grub-install command and add the parameter --removeable

$ grub-install --target=x86_64-efi --efi-directory=/boot/efi --removable