Creating the Kickstart File for a Live CD
To make a more useful live CD or DVD, you can start with one of the livecd-creator desktop kickstart files. (Refer to the official kickstart page for details about the format of this file.) This section shows the contents of the livecd-fedora-8-base-desktop.ks file, divided into three sections (preinstall, packages, and post-install).
To build your own Fedora desktop live CD, you should start with either the KDE (livecd-fedora-8-kde.ks) or GNOME (livecd-fedora-8-desktop.ks) live CD desktop kickstart file. Both of these kickstart files include the base desktop kickstart file illustrated in this section.
Setting Preinstall Values in Your Kickstart
The first set of values in the kickstart file sets standard features before the actual install begins. These values in our sample kickstart file include the following:
lang en_US.UTF-8 keyboard us timezone US/Eastern auth --useshadow --enablemd5 selinux --enforcing firewall --disabled xconfig --startxonboot part / --size 4096 services --enabled=NetworkManager --disabled=network,sshd repo --name=released --mirrorlist=http://mirrors.fedoraproject.org/mirrorlist?repo=fedora-8&arch=$basearch repo --name=updates --mirrorlist=http://mirrors.fedoraproject.org/mirrorlist?repo=updates-released-f8&arch=$basearch
If you’ve installed Fedora on previous occasions, you’ll notice that the entries in this first section of a kickstart file answer many of the questions you get during a regular install:
- By default, this file creates a United States/English live CD.
- The language is U.S. English (lang en_US.UTF-8).
- The keyboard is U.S. (keyboard us).
- The time zone is set to East Coast United States (timezone US/Eastern).
- Security settings include standard shadow passwords used with MD5 encryption (auth --useshadow --enabledmd5), SELinux set to be turned on (selinux --enforcing) and iptables firewall features are off (firewall --disabled).
- With xconfig set to --startxonboot, the live CD will be configured to boot to a graphical login screen. Only a single partition is created (/) and it’s set to be at least 4096MB. The default services running on the live CD are modified to have the network service and Secure Shell (sshd) service on, with networking managed by the Network Manager service.
- The two repo entries are important because they point to the Fedora repository where livecd-creator will get the software. The exact site chosen is taken from a mirror list. In this case, the Fedora 8 basic and updates repositories are used, so you can get the latest updated software for Fedora 8.
The following table shows some ways to modify or add more settings in this section.
Disable SELinux by setting selinux --disabled
Disable the GUI on boot by setting skipx instead of xconfig
Change bootloader timeout
Change the length of timeout from the boot screen to system boot by using bootloader --timeout=n (replace n with the number of seconds before timeout)
Add boot options
Use bootloader --append to add kernel options at boot time; fr example, bootloader --append="noprobe 3" causes the live CD to not probe hardware and start in runlevel 3
Use specific repositories
Instead of using --mirrorlist to choose a repository to use, you can indicate a specific repository with the --baseurl option.
If you decide to specify repositories, you can point to either an online Fedora yum repository or a local file, as in the following examples:
repo --name=release --baseurl=http://frp.udl.es/pub/fedora/linux/releases/8/Everything/i386/os repo --name=newrepo --baseurl=file:///var/tmp/newrepo
Notice that the second repo example points to a local directory:
repo --name=updates --mirrorlist=http://mirrors.fedoraproject.org/mirrorlist?repo=updates-released-f8&arch=$basearch
The pointer could offer a way to include your own software packages (RPMs) in the live CD. That directory has to contain the RPM packages you want and be configured as a yum repository using the createrepo command (described later).
Likewise, if you have a Fedora repository available from your local system (from a local directory or DVD), you can point the repo line to that repository and save a lot of download time. For example, the Fedora 8 and Red Hat Enterprise Linux Bible (Wiley, 2007) comes with an 8GB Fedora 8 install DVD. I used the following repo lines when I built a live CD with that DVD inserted:
repo --name=release --baseurl=file:///media/Fedora\ 20071108\ i386\ DVD repo --name=updates --mirrorlist=http://mirrors.fedoraproject.org/mirrorlist?repo=updates-released-f8&arch=$basearch
This approach saved me from having to download most of the packages needed to build the live CD, but also grabbed new packages for which updates were available.
Adding Packages to Your Kickstart File
In the packages section of the kickstart file, you indicate which groups of packages you want installed, any individual packages you want installed, and packages you want to prevent from being installed. (For example, you might want to exclude a package that was being pulled in as part of a selected group.) The following example shows some of the package list in the sample kickstart file:
%packages @base-x @base @core @admin-tools @dial-up @hardware-support @printing kernel memtest86+ # save some space -specspo -esc -samba-client -a2ps -mpage . . . %end
Notice that the package list begins with %packages and ends with %end. Each group is indicated by the at sign (@). Added packages are simply listed by name, and removed packages are preceded by a hyphen (-).
Once you’ve chosen a starting package list, there are several options to consider regarding the packages you add or remove from your package list:
- Check available packages. Use Package Manager (Applications > Add/Remove Software, or type pirut) to see available groups and packages. Use yum search to search or yum list | less to list all packages.
- Compressed file system. Because livecd-creator uses mksquashfs to compress the live CD’s file system to less than 1/3 of its normal size, you can fit more on a live CD than you would get on a regular hard disk install. So, for example, the file system on the minimal install CD before it’s compressed is about 460MB, but the resulting squashfs image is only 114MB.
- Getting a list of packages. If you installed Fedora to your hard disk, a kickstart file (anaconda-ks.cfg) reflecting that installation is copied to the /root directory. Although not all the information in that file is needed for live CD creation, you can use the %packages section as the basis for the live CDs you create.
- Selecting packages for CD vs. DVD. Aside from size, there’s no difference between selecting packages for a CD versus a DVD ISO image. You can just select more packages for a DVD, because there’s more room on the disc.
Adding Post-Install Commands to Your Kickstart File
The post section of the kickstart (indicated by %post) is where you can modify the contents of the live CD after all the packages have been downloaded and installed to the temporary directory. Because the code in the post section is a bit ugly, I’ll give you the highlights from the sample kickstart and make suggestions on commands you might want to add:
Adding a User
The following lines add the "fedora" user account with a blank password:
useradd -c "Fedora Live" fedora passwd -d fedora > /dev/null
By default, firstboot (which lets you configure firewalls, SELinux, a new user, and other features when you boot the CD) is off by default. If you like, you can turn it on by changing NO to YES in the following line:
echo "RUN_FIRSTBOOT=NO" > /etc/sysconfig/firstboot
Turning Services On or Off
The sample kickstart uses the chkconfig command to turn off certain services. Here, six services are turned off for the common run levels (3, 4, and 5):
chkconfig --level 345 yum-updatesd off 2>/dev/null chkconfig --level 345 crond off 2>/dev/null chkconfig --level 345 atd off 2>/dev/null chkconfig --level 345 anacron off 2>/dev/null chkconfig --level 345 readahead_early off 2>/dev/null chkconfig --level 345 readahead_later off 2>/dev/null
The livecd-creator command includes a way to add files to a live CD’s file system. By having a %post --nochroot section at the end of the kickstart file, you can modify the live CD’s file system after all the packages have been installed. In the sample kickstart file, that section copies the GPL and a readme file from the installed system ($INSTALL_ROOT) to a directory on the live CD ($LIVE_ROOT):
%post --nochroot cp $INSTALL_ROOT/usr/share/doc/*-release-*/GPL $LIVE_ROOT/GPL cp $INSTALL_ROOT/usr/share/doc/HTML/readme-live-image/en_US/readme-live-image-en_US.txt $LIVE_ROOT/README %end
You can add your own data files to the live CD by doing a similar copy in the %post --nochroot section. Here’s an example of how you might add your own music files to a Fedora live CD:
%post --nochroot cp -ar /home/chris/Music $LIVE_ROOT/ %end
Changing the Desktop
As you further tailor your live CD, you may want to change the look and feel of your desktop. To see ways in which this can be done, look at the livecd-fedora-8-kde.ks file. The post section of that file sets up the KDE desktop to be the default desktop environment, and does other things such as disabling the screen saver and doing auto-login.
One way that I add custom desktop settings to a live CD is to configure a desktop exactly as I would like it on an installed system, and then copy the resulting configuration files from that user’s home directory to the /etc/skel directory on the live CD. If you can do that before the Fedora user is added to the live CD, all those settings are automatically copied to the Fedora user’s home directory.