Choosing a linux distribution

Ten years ago a Finnish graduate student named Linus Torvalds announced on a Usenet newsgroup that he had begun working on a small Unix-like operating system for the Intel 80386 processor platform. "Just a hobby," he wrote.

Today that operating system, Linux, runs on everything from very small mobile and embedded devices to mainframes. And IBM, the world's largest computer company, has pledged to invest $1 billion in it.

Not bad for a hobby.

Torvalds released Linux under the GNU General Public License (GPL) created by Richard Stallman. In 1984 Stallman, disappointed that computer manufacturers had begun charging for software, had founded the Free Software Foundation (FSF) and created the GPL. The license requires that a program's source code be open and freely available, and that any software based on other code released under the GPL also be freely available.

Many people may be surprised to discover that Linux has been around for so long, since only the dramatic rise of the commercial Internet in the late 1990s has brought it to the forefront. In fact, Linux is just one of many open-source programs that have been around for many years. Others include Apache, Bind, and Sendmail, as well as the BSD TCP/IP code. A popular argument in favor of open-source, put forth by Eric Raymond in his seminal work The Cathedral and the Bazaar, is that the software is of high quality because "Given enough eyeballs, all bugs are shallow."

In some circles, the definition of operating system is a topic guaranteed to start a flame war. To many Microsoft Windows users it refers to a single application that includes a lot of the software they use to interact directly with their computer. To a Linux user, however, the term is a catchall for many different, small, independent yet interconnected pieces of software.

This concept permeates Linux and, in a larger sense, all versions of Unix: smallish, discrete, replaceable components interacting to provide an overall service. While this idea has the advantage of flexibility and robustness (Linux advocates scoff at the need to reboot an OS after installing software), it also makes managing the software harder for the average user.

At the heart of any Unix operating system, including Linux, is the kernel, which talks directly to the hardware, manages the system's memory, and schedules when each process can execute. It is the operating system's accountant, traffic cop, and bouncer all rolled into one.

A kernel alone does nothing interesting, though, and must be accompanied by a slate of tools, utilities, and other programs—some almost as low-level as the kernel—that perform tasks such as file system management, memory allocation, and hardware control. People new to Linux are often surprised to find that many of the commands they use, such as ls and cd, are really launching small independent programs. Most of these were written not by the Linux developers but by the FSF. So much of any Linux system is actually GNU tools that many FSF advocates insist that Linux should rightfully be called GNU/Linux.

Even the most visible component of an operating system, the graphical user interface, or GUI, is just another application to Linux, albeit a large one. The GUI consists of the windowing system—usually XFree86—and the window manager, of which the most widely used today are KDE (the K-Desktop Environment) and GNOME. Unlike Windows users, Linux users can put a variety of faces on top of the operating system.

Distro-Tech

Anyone can build his own Linux OS by assembling components (and some people actually have), but the process is extremely complex and time-consuming. This is where many commercial and noncommercial entities have found their place in the open-source ecosystem. Several organizations have removed much of the labor and tedium of acquiring, installing, and administering Linux applications by creating distributions (often referred to in Linux parlance as "distros"), which add installers, management tools, software management systems, and other utilities.

Because of the GPL, organizations can't charge for Linux itself. Instead, they've created products by wrapping these higher-level tools around the core of Linux, bundling them onto one or more CDs, and selling them with the promise of support.

Because Linux is componentized and customizable, distribution vendors are able to pick a niche and tailor their products to fill it. Mandrake, for instance, is the easiest to install, and the distribution best suited for new users unfamiliar with Unix. Debian pulls in the opposite direction, focusing on standards, security, and software stability. Debian often waits longer to incorporate new versions of software to make sure that most bugs and security holes have been identified. But at the core they are all Linux, and they all run the same software. An experienced user will feel at home on any of them, but each tends to develop its own personality and its own base of supporters.

Up for Adoption

Linux's flexibility, coupled with its low (or free) cost and ability to run on low-end hardware, helped early adopters sneak it into a lot of corporate networks. Another plus is that Linux is an excellent network chameleon: It can share files and printers with NetWare, Unix, and Windows clients.

Linux as an operating system has moved beyond the early adopters and is beginning to be accepted by the mainstream. The U.S. Post Office uses Linux to sort mail. Cisco's worldwide printer network runs on Linux, and the company has released the in-house–developed software that runs it back to the open-source community. Even institutions as traditionally conservative as the New York Stock Exchange recently began adopting Linux for stock trading.

Still, Linux has been slow in making inroads into the desktop space usually reserved for Windows and Mac OS. While Unix fans and developers may love Linux on their workstations, most of the attention it receives is as a server. But great strides are being made toward creating a system that the average AOL customer can use; the most recent KDE and GNOME window managers are beginning to rival the usability of Windows and Mac OS.

Still, the complex Unix core remains just beneath the surface, requiring some Unix competence from the user. According to a Linux study by IDC, the biggest hurdle facing those considering the adoption of Linux is the lack of in-house expertise. The other factors commonly cited as a deterrent to its use are the lack of platform vendor support and the reluctance to add yet another operating system to the list needing support.

In addition, while there are many fine Linux applications compatible with popular Windows and Mac programs, such as the StarOffice productivity suite and GIMP image editor, compatibility goes only so far, and most companies and mainstream users are still reluctant to adopt these alternatives. Linux's best opportunity for widespread desktop adoption may have to wait until the world moves to browser-based applications in which the desktop operating system becomes less relevant.

So, with the potential negatives, why would an IT shop choose to deploy or migrate to Linux? Mostly because once the learning curve has been scaled, some impressive benefits are gained. The most important one, and the one most frequently cited, is that Linux users are not beholden to a single company or any company at all. They don't have to worry about whether the vendor is going to raise prices, discontinue support for the software, or go out of business.

There are many other benefits, including the increasing rate of development for Linux applications and support. A new kernel with better symmetric multiprocessing (SMP) support has enabled Linux to push the server farther up the corporate IT food chain. Several journaling file systems have been added; these maintain a log of updates to the data on the hard drive so it can be restored in the event of a crash, making data loss from crashes much less likely. And the range of hardware supported has increased as companies release drivers for Linux as well as Windows. Some large hardware vendors, including Dell and IBM, are even shipping systems with Linux preinstalled.

Once you've resolved to choose Linux, the question becomes which Linux to choose. We examine six of the most popular distributions to help you make that decision.

Copyright ?? 2004 Ziff Davis Media Inc. All Rights Reserved. Originally appearing in PC Magazine.