Goal is to install new OS from an ISO image without creating a boot CD.
Step 1: Format hard disk to be used with a boot partition. (set boot flag)
Step 2: Mount partition, create new directory named ‘boot’ (in this case the partition automatically mounted as /media/brian/boot, so new directory is /media/brian/boot/boot). Copy the ISO file(s) you want to use to a subdirectory named grml. (or anywhere else)
Step 3: Use ‘fdisk -l’ or ‘parted -l’ to figure out what the drive is (in this case it is /dev/sdj)
Step 4: Install grub2 to the disk and specify a boot directory (if you don’t specify the boot directory, it will assume /boot — which is your current system. (assume grub2 is already installed)
$ sudo grub-install –boot-directory=/media/brian/boot/boot /dev/sdj
Step 5: Unmount hard drive and physically install it in new computer, boot up, should get grub> prompt.
Step 6: Use ‘ls’ command to determine location of partition and folder. In GRUB2, disks start with 0 and partitions start with 1. In this case, (hd0,msdos1) is the first partition of the first drive.
grub> ls (hd0,msdos1)/boot/grml
The names of the ISO files I had copied step 2 are shown after this command.
Step 7: Issue the following commands from the grub prompt to boot from the desired ISO file: (tab key works as auto-complete in grub shell) (this is for Ubuntu-style OS)
grub> loopback loop (hd0,msdos1)/boot/grml/xxxx.iso grub> linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=/boot/grml/xxxx.iso noprompt noeject grub> initrd (loop)/casper/initrd.lz grub> boot
Step 8: Now computer should boot up just as if you are booting from a CD/DVD. Install OS as normal. The Ubuntu installer requires the /isodevice to be unmounted, but it can’t do it on its own. So before running the installer:
$ sudo umount -l -r -f /isodevice