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GPL and What You Need to Know

Open Source. General Public License. Linux.

Maybe you've read about them, or maybe know somebody running something with these in the title. But maybe you haven't actually taken any more time to understand the origins of Open Source.

You've heard the buzz and know that it's transforming the IT landscape and making inroads around the globe. But maybe you need some background on what Free and Open Source Software (FOSS) is really about. And what should you know about open source licenses, such as the General Public License?

In this edition of In Focus, you'll get a brief overview of the origins of open source, some related topics to know about, and how to start making sense of the GPL .

1. An Overview of FOSS

The roots of the modern Free and Open Source movement are somewhat debatable, and their provenance is lengthy. So we'll go with an executive summary instead. The BSD (Berkeley Software Distribution) project and its later derivatives are perhaps the first examples of a Free or Open Source operating system, tracing their genesis to 1977.

In and around 1984, Richard Stallman (usually referred to by his initials RMS) founded the GNU project (GNU's not Unix) as an effort to create a free alternative to Unix , the widely used operating system for workstations that once belonged to AT&T. As part of his effort to create a free version of Unix, Stallman created the GNU General Public License in 1989.

By 1991, we were up to version 2. Essentially, the GPL enshrines and defines the nature of free software and is usually held up as the standard against which all other licenses are measured. (But we'll have more on that later.)

Free software has nothing to do with price; it's about software freedom. The quote "Free as in Freedom not Beer" is oft-repeated in the free software community. Free software is a philosophy and a movement that pre-dates the term "open source" by almost 14 years.

Open Source

The term open source was coined in 1998, partially in response to a community-driven initiative led by Bruce Perens and Eric Raymond after Netscape released the source code for its browser (which is the roots of the Mozilla browser and project ). The Netscape source code was released under what was to become known as the Mozilla Public License. Perens and Raymond were looking to make "free software" as defined by the Free Software Foundation (FSF) and its GPL more palatable to commercial interests. The Open Source Initiative (OSI) currently lists over 50 licenses that are considered by it to be "OSI approved."

External links to philosophy of free software and FSF:

Open Source Definition
OSI Approved Licenses
Free Software Foundation
Richard Stallman: Why Software Should Be Free
The GNU Project

Free vs. Open Source

There are numerous differences between "free" and "open source" software. For the free software community, a free software-compatible application is one that offers a license that is either the GPL or is compatible with the GPL. For the open source community, open source is software that is compatible with the open source definition.

But in a more philosophical sense, there is a much deeper division between the two groups.

"The fundamental difference between the two movements is in their values, their ways of looking at the world," Richard Stallman wrote in his paper "Free vs. Open Source Software."

"For the open source movement, the issue of whether software should be open source is a practical question, not an ethical one. As one person put it, 'Open source is a development methodology; free software is a social movement.'

"For the open source movement, non-free software is a suboptimal solution. For the free software movement, non-free software is a social problem and free software is the solution."

The Linux Kernel

One of the things that the GNU project was missing was a kernel. A kernel is the core of an operating system and contains much of the root functions, such as virtual memory, multitasking, shared libraries, demand loading, shared copy-on-write executables and TCP/IP networking.

In 1991, Linus Torvalds wrote and first published the Linux kernel. It has been licensed under the GPL since its 0.12 release while Torvalds holds the copyright to the Linux name. The Linux kernel is the core of the Linux operating systems and is currently at version 2.6, though many popular distributions are running version 2.4.

One issue that has been raised in relation to the interaction of the 2.6 kernel with the 2.4 kernel is the practice of "backporting" features of 2.6 into 2.4. Torvalds supports the practice, saying "it makes sense from a company standpoint to basically 'cherry-pick' stuff from the development version that they feel is important to their customers."

Linux Kernel Issues

The origins of Linux and whether any copyrighted code was taken from Unix is one of the issues at the root of the SCO vs. Linux controversy. (See our Special Report on the SCO/Linux controversy.) . In response, the community , third parties Linux distributions and companies like HP have all moved to indemnify their users against any potential liability that may be involved.

2. What you need to know about Linux and the GPL

We asked OSDL's Open Source Architecture Specialist Bill Weinberg for a quick summary of what enterprise users need to know about Linux and the GPL. Here are some of the highlights:

  • The Linux kernel, GNU software and other FOSS components that comprise the Linux operating system represent the work of thousands of developers over the last decade. Despite the size of that community, the origin of code in Linux is tightly controlled and well-documented. And unlike proprietary software content (with its often-obscure origins) any user, corporation or individual can confirm the pedigree, quality and safety of any part of Linux at any time.
  • There is no "one right way" to deploy Linux. Companies around the world leverage Linux with a mixture of open and proprietary software stacks, building on COTS and custom components that meet their application needs.
  • Using Linux is IP-safe. Running your applications on Linux and storing and distributing your corporate data over Linux in no way impacts the status of your IP or your company's claims to it.
  • Using Linux is secure. The fact that Linux source code is open doesn't make it any less safe from crackers, viruses or other digital malfeasance. The developers of Linux do not believe in security through obscurity, but rather that community oversight and community-based exploit discovery and repair result in a vastly more secure computing environment.
  • You and your company can participate in Linux development and in the open source community at any level you desire. You can contribute to the code base; you can improve the code; you can share your opinions about it; or you can just use Linux to support your IT needs.
  • (Next: Even More Things Enterprise Users Need to Know about the GPL:)