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2021-10-25 - 06:42

Dates and Events:

OSADL Articles:

2021-09-06 12:00

"OSADL Track" at EWC 2022: Call for Papers

All about legal and technical issues and solutions when using Open Source software in industry

2021-02-09 12:00

Open Source OPC UA PubSub over TSN project phase #3 launched

Letter of Intent with call for participation is now available

2016-11-12 12:00

Raspberry Pi and real-time Linux

Let's have a look at the OSADL QA Farm data

2016-09-17 12:00

Preemption latency of real-time Linux systems

How to measure it – and how to fix it, if it's too high?



What is what in the world of "Free Software" and "Open Source Software"?


Developers, testers and users of free and open-source software. Communication generally occurs over the Internet, particularly in newsgroups, but also in conferences and meetings.


The abbreviation for "Concurrent Versions System" - a version administration system that allows several developers at different locations to simultaneously work on one software project. Communication generally occurs over the Internet. This feature made CVS ideal for community projects such as free and open-source software projects. SVN has been recently surplanting CVS.


A split-off of part of the community in a free or open-source software project. Such a split can occur when part of the community is not in agreement with the decisions of the maintainer. Forks are relatively rare.


Abbreviation for free or open-source software. Generic term for free software and open-source software.

Free Software

The user is allowed to use the software in what ever way he or she wants. The software is, however, not necessarily free in terms of cost. The term "free" means free in the sense of a "free exchange of ideas" and not free as in "free lunch." In contrast to "open-source software," the emphasis of the term "free software" is on freedom in a social sense and less on the associated disclosure of program sources. Legally speaking, free software and open-source software are identical.

Free and Open-Source Software License

Special agreement on the use and transmission of computer software. Approximately one-third of free and open-source software around the world is subject to the so-called GNU General Public License (GNU GPL).

GNU General Public License (GNU GPL)

The GNU general public license (GNU GPL) is based on ideas that were formulated in September 1983 by Richard Stallman and specified in 1985 in the GNU Manifesto. Stated simply, this license grants four freedoms and contains one condition:

  • Freedom 1: The freedom to let the software run without restrictions
  • Freedom 2: The freedom to analyze the software and adapt it for your own needs (requires access to program sources)
  • Freedom 3: The freedom to pass on the software to others (with or without payment)
  • Freedom 4: The freedom to improve the software and make the improvements accessible to the public (requires access to the program sources).

Condition: When passing on the software, none of these freedoms may be restricted. If you only use the software yourself, this condition does not apply.

GNU Lesser General Public License (GNU LGPL)

Originally termed the GNU Library General Public License, the LGPL is for special software libraries. If an application uses one or more functions from a GPL library (independent of whether it is statically or dynamically linked) and this application is passed on, the GPL condition takes effect, i.e., the program sources of the entire application must be disclosed.

This is not the case with the LGPL. That is, it is permissible to pass on the application exclusively in binary form. The LGPL is less restrictive than the GPL and is hence termed the "lesser GPL." However, the LGPL has additional restrictions. For example, you must ensure that the application can be linked to more recent versions of library, and changes, reverse engineering and debugging the application may not be forbidden.

Linux Kernel

Operating system whose early version (0.02) was developed by Linus Torvalds and published on the Internet on August 1, 1991. The Linux kernel is subject to the GPL and is available to everyone on the Internet at the URL


Software developer responsible for a specific free software or open-source software project. The maintainer decides whether or not to include suggestions on developing or changing the software. If the maintainer is not sufficiently responsive to the wishes of the other developers, testers and users, an individual member or several members of the community can split off from the project and continue under a different maintainer. Such a split is termed a fork.


E-mail address used to reach everybody who have joined the respective newsgroup. In addition, the entire e-mail traffic of such a newsgroup is generally available in archives. Participants who have joined can quit at a time. People who regularly read and contribute to a newsgroup form a community.

Open-Source Software (OSS)

Software whose program sources have to be disclosed when it is passed on. In contrast to "free software," the emphasis is on the disclosure requirement and hence the pragmatic side when passing on the software, and less on the social aspect. From a legal standpoint, open-source software and free software are identical.


The abbreviation and name of one of the programs of the "subversion" version administration system. It was developed to overcome design flaws of the older CVS system. For example, SVN allows you to include directories in the version control. In addition, version numbers are no longer issued for the individual files, but for all the files and directories of the project. Many projects administered using CVS have switched to SVN.