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
}