How to Display Grub Menu at Boot Time in Ubuntu

In Ubuntu, Grub boot menu is hidden by default. You can display it by pressing “SHIFT” continuously at boot time. This is useful (among other cases) in case you want to boot in Recovery mode.

To make this change permanent:

With your favorite editor (nano in my case)

sudo nano /etc/default/grub

Comment this line

GRUB_HIDDEN_TIMEOUT=0

and save your changes

#GRUB_HIDDEN_TIMEOUT=0

Update grub

sudo update-grub2

Finally, reboot

systemctl reboot