How to install Ubuntu from ISO file?

Solution 1:

Installing Ubuntu to Internal HDD from ISO booted on the HDD

Your /boot/grub/grub.cfg file should have a menuentry similar to:

menuentry "isoname ISO" {
    set root=(hdX,Y)
    set isofile="/[path]/[name].iso"
        loopback loop $isofile
        linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile toram --
        initrd (loop)/casper/initrd
}

The toram item is critical.

Boot the computer selecting the above menuentry.

Unmount all partitions. To unmount the Live iso run:

sudo umount -lrf /isodevice

Confirm all partitions are unmounted. You should be running totally in RAM.

Run the Ubuntu installer. I generally use the Something else option.

You may want to run sudo update-grub on reboot.