sudo nano /etc/grub.d/40_custom && sudo update-grub2
 menuentry "Ubuntu ISO" {
set isofile="/home/isos/ubuntu.iso"
loopback loop $isofile
linux (loop)/casper/vmlinuz.efi boot=casper iso-scan/filename=$isofile noprompt noeject toram
initrd (loop)/casper/initrd.lz
}