I am using Ubuntu “Daily builds” for some time inside Suns VirtualBox. Unfortunately the daily builds are not longer booting inside VirtualBox for more then 2 weeks now. Christian told me about a new feature of Grub2. You can boot ISO images directly from your hard disk without burning them on CD or USB. Awesome feature and I had to try it today. Here is the description on how to do it with Ubuntu 9.10.

First I am using this tiny script to update all daily builds with the zsync tool. It transfers only the changed parts of the ISO so you and the Ubuntu teams save a lot of traffic.

zsync http://cdimages.ubuntu.com/daily-live/current/lucid-desktop-i386.iso.zsync
cd kubuntu
zsync http://cdimages.ubuntu.com/kubuntu/daily-live/current/lucid-desktop-i386.iso.zsync
cd ../netbook
zsync http://cdimages.ubuntu.com/ubuntu-netbook/daily-live/current/lucid-netbook-i386.iso.zsync
cd ../xubunutu
zsync http://cdimages.ubuntu.com/xubuntu/daily-live/current/lucid-desktop-i386.iso.zsync
cd ..
rm `find ./ -name "*.zs-old" `

This script keeps all my daily builds up to date.

Next Step is to enable the grub menu. In Ubuntu it can be done in “/etc/default/grub“. Change the following lines

GRUB_HIDDEN_TIMEOUT=10
GRUB_HIDDEN_TIMEOUT_QUIET=false

With this change you will see a 10 seconds count down when booting up. With the shift-key you get access to the grub boot menu. Next is to add the ISO images to the grub menu. Change to the “/etc/grub.d” dir.

Here you can find the grub menu entries and configuration files. Add your ISO images starting with 50 here. For example my entry for the normal Ubuntu ISO image (50_ubuntu) looks like this:

echo "Adding $(egrep menu[e]ntry $0 | cut -d'"' -f2)" >&2
 cat << EOF
menuentry "Ubuntu 10.04 Daily Build" {
       loopback loop (hd0,3)/ansi/software_and_config/ISOs/ubuntu/lucid-desktop-i386.iso
       linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=/ansi/software_and_config/ISOs/ubuntu/lucid-desktop-i386.iso file=(loop)/preseed/ubuntu.seed quiet splash bootkbd=sg --
       initrd (loop)/casper/initrd.lz
}

My ISO files are stored on sda3 under /ansi/software_and_config/ISOs/ubuntu/. In order to change it for your needs there are 3 elements to change. The loopback line contains your hard disk in grub style (hdx,y  x=0->sda x=1->sdb aso) and the path. The third element to change is in the linux line. Store this file as “50_ubuntu” in “/etc/grub.d“, make it executable with “chmod a+x 50_ubuntu” and activate the changes with “ubdate-grub“. After a reboot you should be able to activate the grub menu with the shift-key and select the new entry. Have fun.

I found some pages on this topic but the description there was not working for me so I changed it. But take a look on your own:

• http://forum.ubuntuusers.de/topic/lucid-lynx-ohne-cd-brennen-auf-realem-system-/#post-2326751
• http://wiki.ubuntuusers.de/GRUB_2/Konfiguration

My blog will be offline on sunday for some time because I will reinstall the server with new HD and Ubuntu 9.04.