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# 5 The origins of the GPL

While the future of Unix had been so muddled in the late 1980s and early 1990s, the GPL, another development with important licensing considerations, reached fruition.

Richard Stallman, the developer of Emacs, was a member of the staff at MIT when his lab switched from home-grown to proprietary systems. Stallman became upset when he found that he could not legally add minor improvements to the system. (Many of Stallman's co-workers had left to form two companies based on software developed at MIT and licensed by MIT; there appears to have been disagreement over access to the source code for this software). Stallman devised an alternative to the commercial software license and called it the GPL, or "GNU Public License". He also started a non-profit foundation, the Free Software Foundation (FSF), which intended to develop an entire operating system, including all associated software, that would not be subject to proprietary licensing. This system was called GNU, for "GNU is Not Unix".

The GPL was designed to be the antithesis of the standard proprietary license. To this end, any modifications that were made to a GPL program were required to be given back to the GPL community (by requiring that the source of the program be available to the user) and any program that used or linked to GPL code was required to be under the GPL. The GPL was intended to keep software from becoming proprietary. As the last paragraph of the GPL states:

“This General Public License does not permit incorporating your program into proprietary programs.”[1]

The GPL is a complex license so here are some rules of thumb when using the GPL:

- you can charge as much as you want for distributing, supporting, or documenting the software, but you cannot sell the software itself.

- the rule-of-thumb states that if GPL source is required for a program to compile, the program must be under the GPL. Linking statically to a GPL library requires a program to be under the GPL.

- the GPL requires that any patents associated with GPLed software must be licensed for everyone's free use.

- simply aggregating software together, as when multiple programs are put on one disk, does not count as including GPLed programs in non-GPLed programs.

- output of a program does not count as a derivative work. This enables the gcc compiler to be used in commercial environments without legal problems.

- since the Linux kernel is under the GPL, any code statically linked with the Linux kernel must be GPLed. This requirement can be circumvented by dynamically linking loadable kernel modules. This permits companies to distribute binary drivers, but often has the disadvantage that they will only work for particular versions of the Linux kernel.

Due in part to its complexity, in many parts of the world today the legalities of the GPL are being ignored in regard to Linux and related software. The long-term ramifications of this are unclear.

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