Why Different Distributions?

One of the questions that I’m asked

frequently is "Why does Linux need distributions at all?" There are various

commercial operating systems, including free ones, which are distributed as a homogeneous

unit. So why are there so many Linux distributions?

The answer has to do with the development

style, philosophy, and commercial interests, or lack of it, of different operating

systems. Most of these other OSs follow the cathedral style of development, where the

details of implementation are a business secret. This is particularly true of

closed-source operating systems.

Linux, on the other hand, has an

aggressively distributed style of development, where even the core of the OS, the kernel,

has hundreds of contributors, and all the components come from diverse sources. Given this

structure, the various Linux distributions serve as integrators, creating an integrated

unit suitable for wider distribution.

What are distributions?

Given that the components

of Linux come from diverse sources, bootstrapping Linux on bare metal, starting from the

source code, is a daunting task, as anyone who’s attempted a fresh port will testify.

Linux distributions arise from the need to address this complexity.

Simplistically, Linux distributions include

the Linux kernel, pre-compiled binaries, and means of installing them. Most distributions

address ease of upgrades and maintainability, and offer add-on components. Broadly

speaking, any current Linux distribution would contain the software needed to do your job,

including kernel and drivers, libraries, utilities, and application programs. However,

there are nuances, and one may find a particular distribution better fitted to his needs

than others.

A common consequence of this multiplicity

of upstream sources is that the distributions tend to be modular. That is, a Linux

distribution is made up of "packages", and each such package has its own

development cycle. The number and quality of packages offered is often a criteria for

selecting the preferred distribution.

Advantage distributions

The primary advantage

of having multiple distributions is simple–choice. Different users have different,

and often conflicting, requirements of their OSs, and Linux distributions have evolved to

fit each niche. In my opinion, this is a good thing.

The second advantage is friendly

competition. Having multiple distributions of the operating system keeps any one

distributor from getting complacent. And as long as the distributions share fixes, and

don’t engage in internecine strife, this is beneficial to the free software

community.

Another advantage is innovation, testing,

and evolution. Anyone who’s read Gordon Dickson’s science fiction

"Dorsai" series is familiar with this concept. In this, the human species goes

to the stars, and evolves along separate paths–the Dorsai are soldiers

extraordinaire, the Exotics have advanced mental abilities, and so on. In a similar

fashion, Linux distributions spring up to fill the needs of niche markets and develop

along different lines. They experiment with different packaging techniques, installations,

or management procedures and programs. As long as these innovations are free and open,

they get integrated into other distributions as well in a modified Darwinian process.

Differing user needs

I mentioned above that the

needs of users are different. This is a time of explosive growth of computer users in

general, and Linux users in particular. Most of these new users are still novices. Add to

the fact that the dominant desktop OS happens to be Windows, it’s not surprising that

a significant fraction of the pool of new Linux users are new to Unix-like

OSs. A

distribution that flattens the learning curve, perhaps something that looks familiar to

someone with a background in Windows would make life easier for them.

At the other end of the spectrum are people

who want to have total control over their machine, perhaps down to compiling all the

software themselves, with their own customized build options. Complexity wouldn’t

scare these users off, though defaults that help the packages meld into a coherent system

would be welcome.

Yet another group is more concerned about

reliability, stability, and up time rather than being on the cutting edge. People running

mission-critical servers would fall into this category. A distribution that specializes in

security infrastructure (incorporating Kerberos, for example) would be popular here.

There are other choices as

well–commercial software integrated into the system, versus uncompromisingly free

distributions. People offering support contracts may need custom distributions.

It would be impossible for a single

monolithic distribution to meet all these diverse needs. And that’s where multiple

distributions come in.