Aapo Rantalainen's blog

Experiences with Information Technology and Open source

Howto: make your own Linux LiveCD

Posted by Aapo Rantalainen on April 16, 2010

I made my own Linux Distribution. Truly speaking I just made my own customized Ubuntu Live CD.

Use Case: I’m working with Linux application and I want show it to users who are not using Linux.

One approach is use virtualised Linux, but what virtualization system to use: VirtualBox, VMware, qemu? I made LIVE cd image, which can be used with any virtualization system or it can burned to CD or copied to bootable USB-stick.

Environment

My problem is that my application uses graphics and audio. And it contains lot of data files (more than 300M).

I used VirtualBox and remastersys. So I first install and configure whole system inside VirtualBox and then made ISO-image with remastersys.

I decided to star with Karmic (Ubuntu 9.10) mini netboot installation cd.

wget http://archive.ubuntu.com/ubuntu/dists/karmic/main/installer-i386/current/images/netboot/mini.iso

And then made  ‘command line install’. It was easy installation, I just pressed enter in every question.

Graphical -X

Then I have base command line running. First task was install Xorg (graphical).

I decided to use openbox, so I can get start menu.

sudo apt-get install openbox xserver-xorg xinit

This took 90M of space.

Autologin

Actuallu LIVE cd has always autologin, but I wanted start X on start.

So I added in file /etc/bash.bashrc

if [ -z "$DISPLAY" ] && [ $(tty) == /dev/tty1 ]; then
    startx
fi

Xterm

Because I was working inside Virtualbox (there are hard  to achieve virtual console (e.g.ALT-CTRL-F2)), I install also xterm.

sudo apt-get install xterm
sudo touch /usr/bin/xrdb
sudo chmod a+x /usr/bin/xrdb

Xterm gives error if xrdb is not founded.

Start menu

Openbox handles startmenu via file /etc/xdg/openbox/menu.xml

It is very straighforward to throw useless stuff away and add one new entry.

Sounds

This was harder part. Normally sounds are handled via desktop environment.

This is minimal what is needed to use audio:

sudo apt-get install linux-sound-base alsa-base alsa-utils

User must belong to group ‘audio’ to use audio. This was tricky, because nothing I change for this user will not go to LIVE-cd.

I added to file /etc/rc.loca (before exit 0)

adduser custom audio

(I knew my LIVE user will be ‘custom’)

For some mysterious reason sound doesn’t work very well. I decided to install pulseaudio too.

sudo apt-get install pulseaudio pavucontrol

And /etc/xdg/autostart.sh

pulseaudio -D

Normally login manager is handling this, but we do not have login manager at all.

Simple way to test audio

arecord > tmpfile
aplay < tmpfle

Use CTRL+c to break recording.

Changing volume and unmuting

Use both alsamixer (command line) and pavucontrol (graphical) to check that audio is unmuted.

Own customization

This is the reason why I’m doing LIVE cd.

sudo apt-get install python-software-properties
sudo add-apt-repository ppa:aapo-rantalainen/jammo-stable-ubuntu
sudo apt-get update
sudo apt-get install jammo

It has lot’s of data and some dependencies and it uses 485M.

Remastersys

This is not only tool to make LIVE-cd, but this is easy and it fetch all needed dependencies sametime.

echo 'deb http://www.geekconnection.org/remastersys/repository karmic/' | sudo tee -a /etc/apt/sources.list
sudo apt-get update
sudo apt-get install remastersys

This will add 55M to disk usage.

Making disk

There are config files in /etc/remastersys.conf and /etc/remastersys/isolinux/isolinux.cfg
First contains username and hostname, latter contains start up menu and timeout for it. I set TIMEOUT=1 and empty isolinux.txt.

Then run:

sudo remastersys dist

Copy ISO out of VirtualBox and run

sudo remastersys clean

Result

If you want  test my LIVE cd, read section “Live CD containing JamMo” on http://jammo.garage.maemo.org/download.html

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