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$FreeBSD: head/en_US.ISO8859-1/articles/bsdl-gpl/article.xml 53942 2020-03-01 12:23:40Z carlavilla $
Long before the term <quote>Open Source</quote> was used, software was developed by loose associations of programmers and freely exchanged. Starting in the early 1950's, organizations such as <link xlink:href="">SHARE</link> and <link xlink:href="">DECUS</link> developed much of the software that computer hardware companies bundled with their hardware offerings. At that time computer companies were in the hardware business; anything that reduced software cost and made more programs available made the hardware companies more competitive.
In 1969 the US Department of Justice charged IBM with destroying businesses by bundling free software with IBM hardware. As a result of this suit, IBM unbundled its software; that is, software became independent products separate from hardware.
Universities rapidly adopted Unix after an OS conference publicized its availability. It was extremely helpful that Unix ran on the PDP-11, a very affordable 16-bit computer, and was coded in a high-level language that was demonstrably good for systems programming. The DEC PDP-11 had, in effect, an open hardware interface designed to make it easy for customers to write their own OS, which was common. As DEC founder Ken Olsen famously proclaimed, <quote>software comes from heaven when you have good hardware</quote>.
Unix author Ken Thompson returned to his alma mater, University of California Berkeley (UCB), in 1975 and taught the kernel line-by-line. This ultimately resulted in an evolving system known as BSD (Berkeley Standard Distribution). UCB converted Unix to 32-bits, added virtual memory, and implemented the version of the TCP/IP stack upon which the Internet was essentially built. UCB made BSD available for the cost of media, under what became known as <quote>the BSD license</quote>. A customer purchased Unix from AT&amp;T and then ordered a BSD tape from UCB.
A lengthy series of articles published slightly later in Dr. Dobbs magazine described a BSD-derived 386 PC version of Unix, with BSD-licensed replacement files for the 6 missing 4.4 lite files. This system, named 386BSD, was due to ex-UCB programmer William Jolitz. It became the original basis of all the PC BSDs in use today.
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:
The <link xlink:href="">GPL</link> 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.
Remember that the GPL requires anything that statically links to any code under the GPL also be placed under the GPL. The source for this code must thus be made available to the user of the program. Dynamic linking, however, is not considered a violation of the GPL. Pressure to put proprietary applications on Linux became overwhelming. Such applications often must link with system libraries. This resulted in a modified version of the GPL called the <link xlink:href="">LGPL</link> ("Library", since renamed to "Lesser", GPL). The LGPL allows proprietary code to be linked to the GNU C library, glibc. You do not have to release the source code which has been dynamically linked to an LGPLed library.
If you statically link an application with glibc, such as is often required in embedded systems, you cannot keep your application proprietary, that is, the source must be released. Both the GPL and LGPL require any modifications to the code directly under the license to be released.
One of the serious problems associated with proprietary software is known as <quote>orphaning</quote>. This occurs when a single business failure or change in a product strategy causes a huge pyramid of dependent systems and companies to fail for reasons beyond their control. Decades of experience have shown that the momentary size or success of a software supplier is no guarantee that their software will remain available, as current market conditions and strategies can change rapidly.
For those who must work with statically-linked implementations of multiple software standards, the GPL is often a poor license, because it precludes using proprietary implementations of the standards. The GPL thus minimizes the number of programs that can be built using a GPLed standard. The GPL was intended to not provide a mechanism to develop a standard on which one engineers proprietary products. (This does not apply to Linux applications because they do not statically link, rather they use a trap-based API.)