Published on Nov 19, 2010

Build Your Own Linux Live CD/DVD Distribution based on Ubuntu

GNU Linux

GNU Linux

Well then, you wanna make your own linux live distribution :) I’m here going to show you a rather easier and simpler way than building linux from scratch. We will be creating a customized distribution based on ubuntu. You might have already seen some successful distributions like Linux Mint, Fluxbuntu, OpenGEU etc that were created using ubuntu as base. So let’s start making our own distro using an ubuntu live cd iso. If you don’t already have the iso, you can download the latest version from here.

Install Necessary Tools
The first thing you need to do is to install the required tools for extracting the iso image and for creating the read only file system named as squashFS, used to create live CD/DVD. To install them, run the terminal and use the following command:

sudo aptitude install squashfs-tools genisoimage

Extract the ISO
Now create a directory named codinglogslinux or whatever name suits you and copy/move the ubuntu iso into that directory. I would love to use shell to do that :P

mkdir ~/codinglogslinux
mv ubuntu-10.10-desktop-i386.iso ~/codinglogslinux
cd ~/codinglogslinux

Well now mount the iso file using the following commands:

mkdir mnt
sudo mount -o loop ubuntu-10.10-desktop-i386.iso mnt

Now you can get the iso file contents in mnt directory. Lets extract everything except the squashFS filesystem inside the iso into a new directory named extract-cd.

mkdir extract-cd
rsync --exclude=/casper/filesystem.squashfs -a mnt/ extract-cd

We will now extract the squashFS filesystem located inside the iso file to create a virtual ubuntu installation where we can make our changes and then rebuild the changed system back into the squashFS filesystem inside the iso file. To extract the squashFS filesystem, use the following commands:

sudo unsquashfs mnt/casper/filesystem.squashfs
sudo mv squashfs-root edit

The unsquashfs command might take some time to finish. This is normal because it’s going to copy many files from the readonly filesystem to our virtual ubuntu environment.

Prepare the Virtual Environment
We need to configure the virtual system now to enable network connection for later use. We need to set the proper DNS addresses for our network in the resolve.conf file. You may also need to copy the hosts file depending on your configuration. To do this simply use the following commands:

sudo cp /etc/resolv.conf edit/etc/
sudo cp /etc/hosts edit/etc/

Now mount important directories of your host system. This will enable you to use the system resources and run any process/program inside the virtual environment. If you later decide to delete the edit directory, then make sure to unmount them before doing so, otherwise your host system will become unusable and you have to reboot the system then.

sudo mount --bind /dev/ edit/dev
sudo chroot edit
mount -t proc none /proc
mount -t sysfs none /sys
mount -t devpts none /dev/pts

Now to avoid locale issues and in order to import GPG keys use the following commands:

export HOME=/root
export LC_ALL=C

Now your virtual system is prepared for making any customizations you need.

Lets do some customizations

APT-GET install/remove any package
Before installing or upgrading any packages, you might need to run the following commands:

dbus-uuidgen > /var/lib/dbus/machine-id
dpkg-divert --local --rename --add /sbin/initctl
ln -s /bin/true /sbin/initctl

To view installed packages by size, use the following command:

dpkg-query -W --showformat='${Installed-Size}\t${Package}\n' | sort -nr | less

Now you may want to remove any package you don’t like :) Well then just remove that using this simple command:

aptitude purge YOUR-PACKAGE-NAME-HERE

To install any new package, just use aptitude install as usual:

aptitude install YOUR-PACKAGE-NAME-HERE

Many more customizations are possible. There is no limit to how extent you can customize the system. You can change default themes, add new themes and UI widgets, add media codecs and new software, install deb files, change different system level settings, update the kernel, optimize system scripts, add language specific files for localization and whatever innovation you might be able to think of. Some basic customization examples are as follows.

Change the desktop background
Normally desktop background files are located in /usr/share/backgrounds directory. For our case this directory inside the virtual system is located in ~/codinglogslinux/edit/usr/share/backgrounds. So copy your background png file to that directory and adjust the owner and file access to make that available for any user of this system and then edit the following files:

  1. ~/codinglogslinux/edit/usr/share/gnome-background-properties/ubuntu-wallpapers.xml and
  2. ~/codinglogslinux/edit/usr/share/gconf/defaults/16_ubuntu-wallpapers or other files in the same directory. by changing the string ~/codinglogslinux/edit/usr/share/backgrounds/warty-final-ubuntu.png to point to your file.

Change Fonts, Colors, Panel options
To do this change or add attributes to configuration files such as: ~/codinglogslinux/edit/var/lib/gconf/debian.defaults/%gconf-tree.xml or ~/codinglogslinux/edit/etc/gconf/gconf.xml.defaults/%gconf-tree.xml

Customize Live CD kernel and Boot Loader
You can change the livecd kernel, by copying the vmlinuz and initrd you want in place of the ones you find in extract-cd/casper.

You can also change the default loading screen by changing the plymouth theme located in ~/codinglogslinux/edit/lib/plymouth directory There are bunch of other things you can customize, those are not in scope of this article. Use your creativity and requirements to do the rest. Now lets repack everything.

Repacking the Distribution

Cleanup everything
Lets remove all the temporary files that are no longer needed.  To do this use the following commands:

aptitude clean
rm -rf /tmp/* ~/.bash_history
rm /etc/resolv.conf
rm /var/lib/dbus/machine-id
rm /sbin/initctl
dpkg-divert --rename --remove /sbin/initctl

now unmount special filesystems and exit chroot:

umount /proc
umount /sys
umount /dev/pts
exit
sudo umount edit/dev

Note: if “umount /proc” command fails try “umount -lf /proc”.

Regenerate Manifest

chmod +w extract-cd/casper/filesystem.manifest
sudo chroot edit dpkg-query -W --showformat='${Package} ${Version}\n' > extract-cd/casper/filesystem.manifest
sudo cp extract-cd/casper/filesystem.manifest extract-cd/casper/filesystem.manifest-desktop
sudo sed -i '/ubiquity/d' extract-cd/casper/filesystem.manifest-desktop
sudo sed -i '/casper/d' extract-cd/casper/filesystem.manifest-desktop

Compress everything back to SquashFS Filesystem

sudo rm extract-cd/casper/filesystem.squashfs
sudo mksquashfs edit extract-cd/casper/filesystem.squashfs

This process will take some time as it is normal because all the files are going to be packed into the readonly filesystem once again :)

Now you may want to set an image name of your choice then the one provided with ubuntu, right? Just edit the file in extract-cd/README.diskdefines and make necessary changes.

Calculate md5 sums

cd extract-cd
sudo rm md5sum.txt
find -type f -print0 | sudo xargs -0 md5sum | grep -v isolinux/boot.cat | sudo tee md5sum.txt

Create the ISO image

sudo mkisofs -D -r -V "$IMAGE_NAME" -cache-inodes -J -l -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -o ../codinglogs-linux.iso

Well congrats, you now have the iso created inside the working folder of your distribution. You can test it using any virtualization software like vmware or so. You can also burn it to any CD/DVD or penDrive. So that’s it, you’ve got your own customized linux distribution :)

There are some GUI tools like Remastersys or UCK to do this work easily. But then you are binded to the customizations these tools offer. They do offer many customization though, but for advanced customizations that can help you make a real distribution rather than just another compiled ubuntu, it’s better to follow the manual instructions described here.

7 Comments + Add Comment

  • Alaric

    December 9, 2010 at 3:31 pm

    This looks very interesting–I will have to try this this weekend. Thanks for taking the time to write this tutorial up; it was just what I was looking for!

  • Tech4wilco

    November 15, 2011 at 1:26 pm

    very nice! good article it works perfectly!

  • Kristian Bremberg

    February 18, 2012 at 6:10 pm

    It worked, but after boot I need to log in? I don’t have any user nor password.

  • gaurav

    May 1, 2012 at 10:05 am

    Excellent article I was searching for this for a year….. THANK YOU VERY MUCH

  • Sansibar

    May 9, 2013 at 2:29 pm

    This is so far the best tutorial i’ve seen.
    Very clear, very straight.
    Only the genisoimage faild first, but with a change I made it finally.
    Now I have my “”own”" Xubunt 13.04

    Thank you so much!

    • iSR

      June 19, 2013 at 11:49 pm

      Thanks to Masum great tutorial, but i’ve the genisoimage problem.

      Sansibar could you tell me how you solved that problem.

      thanks

  • Gunner

    February 1, 2014 at 3:09 am

    I’m going to make a Linux distro.

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