Assuming you loopback mount the ISO, I think these are the major args... fill in the "..." wherever you see them: # Ubuntu linux .../vmlinuz boot=casper fi

Assuming you loopback mount the ISO, I think these are the major args... fill in the "..." wherever you see them: # Ubuntu linux .../vmlinuz boot=casper file=.../ubuntu.seed iso-scan/filename=... initrd ... # Arch linux .../vmlinuz img_dev=... img_loop=... earlymodules=loop initrd ..._ucode.img .../archiso.img # Kali linux ... boot=live components findiso=... # noautomount initrd ... # GParted linux ... boot=live union=overlay config components toram=....squashfs findiso=... initrd ... In general you'll have to boot the kernels directly as shown above. Using the built-in GRUB menus won't work in many cases. Which makes it difficult to make these future-proof. You'll also want to make sure you've insmod'ed any modules you need for your hardware as necessary (storage, USB, etc.)... unfortunately documentation on these is poor, and some modules are mutually exclusive, so have fun. Best of luck getting a robust boot menu script going. Expect to spend weeks if not months on it if you're new to GRUB scripts/components.