[PLUG] How do live CD's work

Rahul Sundaram sundaram at fedoraproject.org
Mon Oct 22 17:44:01 IST 2007

Devendra Laulkar wrote:
> Hi,
> I would like to understand how live cd's work. I tried
> to find out docs on the net, but I couldn't find
> anything concrete explaining the fundas of live cd's.
> Any pointers / resources welcome.


Different distributions have somewhat varied implementations. Here is 
how Fedora Live CD tools work.


# Sets up a file for the ext3 file system that will contain all the data 
comprising the live CD

# Loopback mounts that file into the file system so there is an 
installation root

# Bind mounts certain kernel file systems (/dev, /dev/pts, /proc, /sys, 
/selinux) inside the installation root

# Uses a configuration file to define the requested packages and default 
configuration options. The format of this file is the same as is used 
for installing a system via kickstart.

# Installs, using yum, the requested packages into the installation 
using the given repositories

# Optionally runs scripts as specified by the live CD configuration file.

# Relabels the entire installation root (for SELinux)

# Creates a live CD specific initramfs that matches the installed kernel

# Unmounts the kernel file systems mounted inside the installation root

# Unmounts the installation root

# Creates a squashfs file system containing only the ext3 file (compression)

# Configures the boot loader

# Creates an iso9660 bootable CD


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