| Using a liveCD as your Linux Desktop |
A guest column by Frank Richards (Dec. 22, 2005)
Most of the "Desktop" Linux liveCD distributions (distros) are meant to to be used for trying out or demoing Linux before installing them to your hard drive. Popular distros like Ubuntu, Mepis, and PCLinuxOS are good examples and in my mind are some of the best offerings. I've been there and done that. These are great distros, and there are many more! If you're looking for a Linux distribution to install on your hard drive, these are all great distros, and you won't be disappointed. Test drive the liveCD, install to your hard disk, and enjoy.
However, many liveCD distros can be used as a day to day desktop without ever installing them to your hard drive. Huh? Wait a minute, everyone installs the OS to a hard disk! Well yes, that's the way it has always been done, but I am not sure why we should continue in that direction... "ah, but I was so much older then, I'm younger than that now" (Robert Allen Zimmerman).
Why would anyone want to use a Linux liveCD as a basic day to day desktop? Here are some thoughts: - Easy to load and update -- Easy, because your data (including configurations) are separate from the operating system (OS). The idea of separating data from the OS has always appealed to me. It seems like a very logical and smart thing to do. Even when I partition a system for a hard drive Linux install, I create a separate partition for /home. Doesn't everybody?
- It's portable -- You can take it with you and securely boot up from just about any PC. Also, Linux liveCDs can often be installed and booted from a USB drive (thanks to some excellent standards around booting from USB drives). This really beats lugging a laptop around (especially when airport security is involved). The downside is that your Live-CD might not boot on all hardware. The distro might not detect the hardware correctly or the hardware might not be able to boot from CD or USB.
- Most run on older PC hardware -- Not only do they run, they usually run quite fast! (Did you ever notice that you usually cannot upgrade old PCs from Windows 95 to Windows XP?) Some of the older PCs don't support booting from CD or USB. In such cases, you can usually copy the CD to the hard drive and create a boot floppy to load the image from the hard drive.
- Security -- It's hard for someone to violate your OS when it resides on a read only CD. And, you can always reboot to a pristine state. This is kind of like going to communion and being forgiven for all past sins. Linux by design is a very secure OS. This just improves on it. Amen.
- It's just plain fun! -- You can remix if you like. You can do your own. This is one of the great things about open source. I am waiting for the next version of Windows XP liveCD. Don't get me wrong here, Microsoft does allow generating DOS 3.1 boot disks so you can network stage new XP clients. But that is more of an enterprise moment...
If you like the idea of using a Linux liveCD on a daily basis, there are several features that need to be present to make this an enjoyable experience: - Saving and restoring configuration data from one session to the next. Specifically, changes to /etc, /usr, /root, and...
- Saving and restoring your home directory. This includes the configuration files for applications like your browser or word processor.
- Adding additional persistent software packages without remixing/re-mastering the CD. Using tools like apt-get or rpm do not meet this need. I cannot download and install applications each time I boot up.
- After boot, freeing up the CDROM for other use (like ripping a CD or just playing CD/DVD). This can be accomplished by loading the entire OS into RAM or by copying the CD image to your hard drive and booting and running from there. Loading your OS into RAM creates a very responsive PC. LiveCD distros without this option do not get much playing time in my space.
Four four-star liveCD Linux distros
Considering the above, if I were to award a star for each feature, how many four-star Linux distros would there be? Of the more popular distributions (per Distrowatch hit count), I would like to highlight four four-stars liveCDs -- Puppy Linux, Kanotix, Damn Small Linux (DSL), and SLAX.
I really like and use all four. They are all capable of saving and restoring system configuration data and home directories. They also each have an easy mechanism to add persistent software packages and they all can be loaded entirely into RAM. One caveat: Kanotix requires a gigabyte or so of memory to load into RAM; however, memory is cheap, and after you get Kanotix loaded into memory, it screams! - Puppy Linux -- developed by Barry Kauler, this small 60MB distro is loaded with applications and is one of the easiest distributions to work with after initial setup. When you boot it up for the first time, it looks for a place to put it's default 250MB file and just does it. It saves everything in this file -- configurations, home directory, and added software packages. Next time you boot up, everything just happens. Software packages are downloaded and installed with PupGet and DotPup tools. Really easy with a good selection of packages to choose from. For the size of this distro, it is really surprising how much you get. Also, it loads and executes in RAM by default. That's a default I can live with!
Puppy has the option of Booting from writable CD or DVD and saving everything back to the CD/DVD. No hard drive or USB drive is needed to save your data or added packages. I have not tried this feature, but it sounds very interesting. This method seems to create an audit trail of everything you do. When the CD/DVD fills up, it copies your current state to new media and continues.
One security concern that I have with Puppy is that you boot up as user root. I would prefer booting up as user doggie or fido and using sudo for commands needing root privilege. Ubuntu has implemented their distros in this manner.
- Kanotix -- developed by Joerg "Kano" Sdhirottke, this distro is somewhat larger (~700MB) than the other distros discussed. It is full featured based on Knoppix and Debian-Sid. It contains many of the latest software applications and is optimized for the i586 architecture. It has the backup/restore and persistent home directory features found in Knoppix.
In addition, Kanotix comes with a software management tool called Klik that allow for easy persistent installation of additional software applications. The Klik agent is installed and ready to use. Each software package from the Klik website consists of one compressed image file (.cmg). After you download this file (of course you put this in your persistent home directory), all you have to do is click on it to load and execute. Simple. If you want to delete the software package, you delete the one file and you are done. The solution is quite flexible and most of the downloaded applications actually work.
- Damn Small Linux (DSL) -- a small (~50MB) distro developed by John Andrews and Robert Shingledecker. DSL's backup/restore methods are unique in that the user can specify the files or directories to backup and restore. Once done, backup and restore are done automatically by default. A cheat code is provided to allow you to override this feature. In effect, this cheat code allows you to be pure again. Amen. It's optional to load the entire image into RAM. Needless to say, it's an option that I always select.
The DSL philosophy is to start small and add any additional software that you need. To do this there are "extensions" or modules that can be loaded at boot time or when needed. All you have to do is download these extensions to your persistent area and they are there for you use at every boot. Very easy! Actually, you can load extensions at boot with cheat codes or manually after boot.
DSL has a very small footprint that can then grow to fill your needs... a great Linux distro.
- SLAX -- this distro is based on Slackware, one of the oldest linux distributions. Developed by Thomas Matejicek, it provides scripts (Linux Live Scripts) for others to create their own liveCDs. And, there have been many takers -- STUX, Goblinix, Buffalo and Mutagenix to name a few. Note that many of these hacks provide four-star features, as outlined above. Note: if you like gnome, Mutagenix is a worthy distro.
SLAX uses "modules" to load system components and applications. This is all done at boot time. So, it is very easy to add additional persistent applications. This same module methodology is used to backup and restore user data and configurations. Very clever. The bottom line
There are many Linux liveCD distros that are not really meant for installation to a hard disk. They can be booted from CD or USB and used as your everyday desktop. They are easy to update, are portable, work on older hardware, are very secure and are great fun. Party on!
About the author: Frank Richards is a graduate of the University of Illinois (EE) and has worked in research, product development, product validation and information technoplogy at Ford Motor Company for the past 35 years. He is currently an Infrastructure Architect in Ford Enterprise
Technology (IT), Dearborn Michigan.
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