How is Linux copyrighted and how does this concern you? That depends on how you intend to use Linux. If, like most people, you will just be an end user, you probably need to read no further. What if you want to use Linux as a software development platform? That's still probably not a problem, unless you develop software that specifically uses Linux and is intended for outside distribution. Here things start to get a little murky. There's a difference between just making system calls (which is okay), and incorporating Linux code as part of your own. If you intend to do the latter, you'll have to meet a few requirements, as described in the rest of this sidebar. The same is true if you intend to redistribute Linux, or any modified portion thereof.The Linux copyright applies the same restrictions as another, well-known copyright, the GNU General Public License (GPL), a.k.a. the GNU CopyLeft. The GPL is a software license offered by the Free Software Foundation, designed to promote rather than discourage the free distribution and use of software. The GPL achieves this by placing certain requirements upon persons who distribute the licensed software.
At the heart of the GPL are three requirements: 1) to make source code available along with any GPL-licensed software that is distributed; 2) to include a disclaimer of warranty; 3) to propagate the GPL license with the distribution.
The first requirement basically states that anyone who distributes software covered by the GPL must be prepared to supply the accompanying source code to users who request it. The same requirement applies to anyone who modifies and distributes GPL-covered software, or incorporates portions of it in code that they distribute. This requirement in effect prevents distributors from reselling the code as proprietary software. (Distributors may, however, charge a fee for distributing the software, and for distributing the source code.)
The second requirement says that persons who distribute GPL-licensed software must make clear that the software's original author provides no warranty protection. This requirement protects software authors who are willing to make their software widely available but cannot afford to provide extensive support.
Finally, the third requirement says that distributors must place on each copy a conspicuous GPL copyright notice, and include an unedited copy of the GPL text. Thus, if the software is distributed to yet another distributor, the GPL will propagate itself through any succeeding distributions.
The above description outlines only the major points of the GPL; there are numerous details too lengthy to reprint here. Also, the GPL is subject to change without notice. For these reasons you may want obtain a copy of the GPL text. You can get the GPL text by writing to Free Software Foundation, 675 Mass Avenue Cambridge, MA 02139.
Marc Briand
Managing Editor