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4. Software that complies with GPL agreement
In the open source field, a license agreement refers to an agreement developed by the open source community in order to maintain the legal rights of authors and contributors and to ensure that the software is not stolen by some commercial organizations or individuals and affect the development of the software. Among them, GPL is one of the very popular license agreements in open source license agreements.
1. Basic concepts
GNU General Public License (English: GNU General Public License, abbreviated GNU GPL or GPL), GPL was written by Richard Stallman in 1989 and was originally provided for use by some software programs listed in the GNU project.
GPL is the most popular license for free software and open source software. As of April 2004, GPL accounted for approximately 75% of the free software listed on Freshmeat and approximately 68% of SourceForge. Similarly, a 2001 survey on Red Hat Linux 7.1 revealed that the general code was released under the GPL.
2. Features of the agreement
2.1 Infectivity
The GPL agreement has a very significant feature "infectiousness": that is, when software with GPL agreement is combined with software under other agreements or GPL derivatives, it must be distributed in accordance with the terms of the GPL. "Derivative products" are usually interpreted as software that contains GPL code or is dynamically linked to GPL libraries. All derivative products under the GPL must belong to the GPL, and the license is operated in accordance with the copyright law.
2.2 Commercially available
GPL software can be used for profit, can be sold at any price, and can be used as a tool for creating proprietary software (for example, a compiler for GPL agreement).
3. The freedom of users
0. Free running
You can run the software as you wish;
1. Free modification
You can modify the software as you wish;
2. Free copy
Free to distribute copies of the software;
3. Free distribution
You can redistribute your modified version of the software to others to give back to open source and promote open source;
4. Software that complies with GPL agreement
Well-known GPL free software includes EMACS, Linux kernel (not all Linux distribution kernels are open source) and GCC.
Five, GPL development stage
GPLv1: solves the problem that software distributors only distribute the binary of the software, but do not provide the software source code; it is required that the entire combination of GPL-compliant software and other software must be distributed under the terms of GPLv1, which limits the restriction of the distributor to increase the license;
GPLv2: stipulates that the licensee can distribute GPL-licensed software only if it meets all the license obligations. Even if there are conflicting obligations, the license obligations may not be cut off, preventing any party from using patent infringement claims or other Litigation to damage the user’s freedom under the license;
GPLv3: Improved compatibility with many open source software licenses (such as Apache License Version 2.0) and GNU Affero General Public License (GPLv2 cannot be combined); the more interesting thing is that Linus Torvalds (Linux The inventor of the kernel and the collaborator of the project) decided not to use GPLv3 as the license agreement for the Linux kernel, and still use the GPLv2 license.
Six, summary
The GPL maintains the legitimate rights and interests of code owners, guarantees the open source of the code and its derivatives, thereby promoting the open source of the code, allowing many software developers to continue to benefit from it, and at the same time, it also continues to give back to the open source community to make the open source team more Come and grow stronger!
Other open source protocols will be introduced later, so stay tuned!
Six, references
[1] https://en.wikipedia.org/wiki/GNU_General_Public_License