I have BackBox Ubuntu installed on a USB flash drive and it boots and runs just fine. However I would like to modify the boot menu but can't find a grub.cfg file. Therefore grub-update will not work. I've also tried using Grub Customizer but it shows both device.map and grub.cfg missing. Most posts I've found with grub.cfg missing have boot problems which I am not having. Is my setup not really using Grub but an alternative boot system? Any help to reconfigure the boot menu on this system would be appreciated.