Activate Grub to show up at start up?

Solution 1:

The menu will appear if you press Shift when grub is loaded. By default you have 10 seconds.

If you want to always see the menu, edit /etc/default/grub. The settings are documented on the Ubuntu website. You may want to:

• Set GRUB_HIDDEN_TIMEOUT_QUIET=false so that Grub shows a countdown to the automatic boot. Press Shift during the countdown to make the menu appear.

• Set GRUB_HIDDEN_TIMEOUT= (nothing after the equal sign) to always display the menu.

• Change the setting for GRUB_TIMEOUT=10 (number of seconds before the automatic boot). The value -1 means that there will be no automatic boot.

Note that spaces are not allowed on either side of the equal sign.

You need to run the update-grub command for the settings to take effect.