A GPL linking exception modifies the

GNU General Public License The GNU General Public Licenses (GNU GPL or simply GPL) are a series of widely used free software licenses, or ''copyleft'' licenses, that guarantee end users the freedom to run, study, share, or modify the software. The GPL was the first ...

(GPL) in a way that enables software projects which provide

library A library is a collection of Book, books, and possibly other Document, materials and Media (communication), media, that is accessible for use by its members and members of allied institutions. Libraries provide physical (hard copies) or electron ...

code to be " linked to" the programs that use them, without applying the full terms of the GPL to the using program. Linking is the technical process of connecting code in a library to the using code, to produce a single

executable file In computer science, executable code, an executable file, or an executable program, sometimes simply referred to as an executable or binary, causes a computer "to perform indicated tasks according to encoded instructions", as opposed to a da ...

. It is performed either at

compile time In computer science, compile time (or compile-time) describes the time window during which a language's statements are converted into binary instructions for the processor to execute. The term is used as an adjective to describe concepts relat ...

or run-time in order to produce functional machine-readable code. The Free Software Foundation states that, without applying the ''linking exception'', a program linked to GPL library code may only be distributed under a GPL-compatible license. This has not been explicitly tested in court, but linking violations have resulted in settlement. The license of the GNU Classpath project explicitly includes a statement to that effect. Many free software libraries which are distributed under the GPL use an equivalent exception, although the wording of the exception varies. Notable projects include ERIKA Enterprise, GNU Guile,Stallman, Richard
Various Licenses and Comments about Them
. Free Software Foundation. Published on 2007-05-17. Retrieved on 2007-05-18. the run-time libraries of

GNAT GNAT is a free-software compiler for the Ada programming language which forms part of the GNU Compiler Collection (GCC). It supports all versions of the language, i.e. Ada 2012, Ada 2005, Ada 95 and Ada 83. Originally its ...

, GNU ClasspathClasspath::License
Free Software Foundation. 2007-04-23. Retrieved on 2007-05-18. and the GCC Runtime Library Exception.GCC Runtime Library Exception
Free Software Foundation. 2009-03-31. Retrieved on 2011-10-18. Compiler runtime libraries also often use this license modification or an equivalent one, e.g. the libgcc library in the

GNU Compiler Collection The GNU Compiler Collection (GCC) is a collection of compilers from the GNU Project that support various programming languages, Computer architecture, hardware architectures, and operating systems. The Free Software Foundation (FSF) distributes ...

, as well as all libraries of the Free Pascal project. In 2007, Sun Microsystems released most of the

source code In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer writes the human readable source code to control the behavior of a computer. Since a computer, at base, only ...

to the class libraries for the Java SE and Java EE projects under version 2 of the GPL license plus the Classpath linking exception, and used the same license as one possible license for their enterprise server

GlassFish GlassFish is an open-source Jakarta EE platform application server project started by Sun Microsystems, then sponsored by Oracle Corporation, and now living at the Eclipse Foundation and supported by OmniFish, Fujitsu and Payara. The support ...

and for their

NetBeans NetBeans is an integrated development environment (IDE) for Java (programming language), Java. NetBeans allows applications to be developed from a set of modular software components called ''modules''. NetBeans runs on Microsoft Windows, Windows, ...

Java IDE.Netbeans license
. 2008-03-27. Retrieved on 2008-03-27. Version 3 of the

GNU Lesser General Public License The GNU Lesser General Public License (LGPL) is a free-software license published by the Free Software Foundation (FSF). The license allows developers and companies to use and integrate a software component released under the LGPL into their own ...

(LGPL) is likewise constructed as an exception to the GPL.Guide to the second draft of LGPLv3
2007-04-03. Retrieved on 2007-05-10.

The Classpath exception

The GNU Classpath project provides an example of the use of such a GPL linking exception. The GNU Classpath library uses the following license: As such, it can be used to run, create and distribute a large class of applications and applets. When GNU Classpath is used unmodified as the core class library for a virtual machine, compiler for the Java language, or for a program written in the Java programming language, it does not affect the licensing for distributing those programs directly.

The GNU Lesser General Public License

While version 2.1 of the LGPL was a standalone licence, the current

LGPL The GNU Lesser General Public License (LGPL) is a free-software license published by the Free Software Foundation (FSF). The license allows developers and companies to use and integrate a software component released under the LGPL into their own ...

version 3 is based on a reference to the GPL. Compared to the GNU Classpath license above, the LGPL formulates more requirements to the linking exception: licensees must allow modification of the portions of the library they use and reverse engineering (of their software and the library) for debugging such modifications.

References

External links

{{DEFAULTSORT:Gpl Linking Exception GNU Project Copyleft software licenses

The Classpath exception

The GNU Lesser General Public License

See also

References

External links