Ubuntu – Boot into Text Mode / Console / Command Line

First backup GRUB file

sudo cp -n /etc/default/grub /etc/default/grub.backup

Edit GRUB file

sudo nano /etc/default/grub

Make following changes

1. Comment the line GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash”, by adding # at the beginning, which will disable the Ubuntu purple screen.
2. Change GRUB_CMDLINE_LINUX=”” to GRUB_CMDLINE_LINUX=”text”, this makes Ubuntu boot directly into Text Mode.
3. Uncomment this line #GRUB_TERMINAL=console, by removing the # at the beginning, this makes Grub Menu into real black & white Text Mode (without background image)

After this update GRUB via below command

sudo update-grub

And reboot

sudo reboot

Revert back
If you want to revert Original settings then first restore GRUB from backup file

sudo mv /etc/default/grub.backup /etc/default/grub && sudo update-grub

And then reboot

sudo reboot