How can I tell if my system was booted as EFI/UEFI or BIOS?

Enter this in the terminal of your choice

[ -d /sys/firmware/efi ] && echo UEFI || echo BIOS

You the querry is UEFI the you use UEFI else BIOS

Source: https://askubuntu.com/questions/162564/how-can-i-tell-if-my-system-was-booted-as-efi-uefi-or-bios/162896#162896