# linux efistub
sudo efibootmgr -b 3 -B 
sudo efibootmgr -c -d /dev/sdb -p 2 -L 'Linux EFISTUB' -l /vmlinuz-linux -u "root=PARTUUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx initrd=/intel-ucode.img initrd=/initramfs-linux.img rw quiet"


# refind
sudo efibootmgr -b 0 -B 
sudo efibootmgr -c -d /dev/sdb -p 2 -L 'rEFInd Boot Manager' -l /EFI/refind/refind_x64.efi