FreeLicenses
Ubuntu is made up of a collection of free and open-source software. This page discusses what free and open-source actually means, and attempts to explain your rights with respect to free software.
Note: Do not use this page as a source of legal advice. It is only intended as a guide, and the correctness of information here cannot be guaranteed.
What is a Free License?
A free license is one which generally grants an individual the legal right to use, copy and distribute material (such as software) without restriction.
- Allow you to distribute or sell the software yourself
- Make the source code of the software available
- Allow you to make modifications and to produce derived works
- Do not allow discrimination against any group of people or people carrying out a specific type of work
- Do not restrict the use of other software
See the Open Source Definition for more information about these points and see Wikipedia for an overview of free software licensing.
Commonly-Used Terms
- Open Source
Open source refers to making the source code of a computer program available to be viewed and possibly modified. It also refers to a way of producing software which is open source; open source software projects often share similar ways of doing things, such as reporting problems with the software. - Free
Free has a couple of different meanings in the English language, but when referring to a free license it means free as in speech (unrestricted). Very often, free software is also free as in beer (no cost), although it doesn’t necessarily have to be. - Source Code
Source code is the actual programming code which makes up a computer program. To use a computer program you must normally compile source code, which turns the program into a form which computers can use but humans can’t. If the source code is made available however, people can read and change the code to alter/improve how the program works. - Proprietary software
Proprietary software is software which doesn’t have a free license and for which there is no open access to its source code. - Dual Licensing
Dual licensing is where software or some other work is distributed under a choice of two licenses. For example, MySQL is distributed under either a free license (which means that you have to release any changes you make to MySQL to the public) or a commercial license (which allows you to make modifications but doesn’t force you to release them to the public). - Copyleft
Copyleft is a type of license which requires that any changes you make to the software must be released to the general public under a free license. This encourages people to share their work and helps to improve the software.
Licenses
- FSF Licenses
The Free Software Foundation is responsible for two of the most popular licenses, the GPL and the LGPL, along with other licenses for documentation and the like. Most of the software in Ubuntu is distributed under the GPL or LGPL. - MIT License
The MIT license is non-copyleft, which means that software can be used in proprietary software. - Creative Commons Licenses
Creative Commons licenses offer a way for authors to distribute their works freely, while preserving certain rights. Creative Commons licenses are normally used on material such as photos, books/articles and music.
Resources
- http://www.fsf.org/licensing/education — A large collection of resources about free software and licensing in general
- http://www.opensource.org/licenses — List of open-source licenses
FreeLicenses (последним исправлял пользователь localhost 2008-07-24 17:11:14)
The material on this wiki is available under a free license, see Copyright / License for details
You can contribute to this wiki, see Wiki Guide for details
What does open source license (like GNU-GPL) mean? [closed]
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I am looking forward to use an open source product which has GNU-GPL like license and it says that if I use that product, I must share the source code of my application. I am slightly confused about it. I understand that Linux is available under GNU-GPL license as well. Does it mean ALL linux application are and has to be open source? Does it mean I can ask for the source code of complete Oracle DB from Oracle Corp (at least the part that runs on Linux)? EDIT: Taken from FAQ:
If a library is released under the GPL (not the LGPL), does that mean that any program which uses it has to be under the GPL or a GPL-compatible license? Yes, because the program as it is actually run includes the library.
I’m voting to close this question as off-topic because it is about licensing or legal issues, not programming or software development. See here for details, and the help center for more.
4 Answers 4
It is important to realize that the «GPL» can refer to two licenses.
- The GNU General Public License
- The GNU Lesser General Public License (aka) The Library General Public License
Either one is very clear to specify that it considers code from a library intermixed with a program as a combined work. This means, if your program loads a library through a dynamic loader (i.e. a common shared object), or links against it statically, the resulting executable is a combined work of the program itself and the libraries that support it.
Now, the differences between the two licenses become very important.
The GPL states that if your program uses a library (or any other code covered by the GPL), it must be released under the same terms as the GPL. This (again) is because the GPL considers the resulting program to be a combined work of your code, plus the work of others.
Fortunately (or not? depending on your views), the GNU C Library is not covered by the GPL. It is covered by the LGPL. The LGPL says that simply loading and using the system C library does constitute a combined work, but an exception is made that allows proprietary applications to do so without having to comply with the distribution requirements of the GPL. So, in this case, Oracle is free to use the system C library (needed to run their code) without being obligated to release their source code.
If Oracle released software that needed to load or link against a GPL covered library, say .. readline() , then yes, they would be obligated to share the code. Oracle (like many others that write software for UNIX-like operating systems) is careful to choose libraries that are released under a more permissive license (aka 2 or 3-clause BSD), or implement their own.
As far as the kernel goes, simply using its syscall interface does not constitute a combined work. While most of us just let the system C library abstract these complexities away, you are completely free to implement your own syscalls under whatever terms you want. This illustrates why the LGPL for the system C library was a very strategic choice. If it were the other way around, GNU/Linux would have deterred more developers than they attracted. Note also, that many of the Linux headers that define the magic numbers needed to talk to the kernel’s syscall interface have no license mentioned whatsoever. See linux/sysctl.h for example, or this note from Linus himself in the COPYING file distributed with the kernel:
NOTE! This copyright does not cover user programs that use kernel services by normal system calls — this is merely considered normal use of the kernel, and does not fall under the heading of «derived work». Also note that the GPL below is copyrighted by the Free Software Foundation, but the instance of code that it refers to (the Linux kernel) is copyrighted by me and others who actually wrote it.
Also note that the only valid version of the GPL as far as the kernel is concerned is this particular version of the license (ie v2, not v2.2 or v3.x or whatever), unless explicitly otherwise stated.
Note, Linus specifically says using the kernel headers and syscall interface does not constitute a derived (as in modified) or combined (as in simply used) work. This, among other things is part of the rift between Linux and GNU. I mention this only because you indirectly mention the ramifications of the GPL. Linus (sometimes) wants code that modifies the kernel, but chose the GPL to ensure the (sometimes) was his choice.
In short, if you link against or load a library that is covered by the GPL, you must make your code available under the same license. If you link against or load a library that is covered by the LGPL, the terms of licensing are up to you.
Note also that the LGPL has a lot more to say, especially regarding modifications, statically linking, etc. What I’ve described is just the bit that answers your question.
Finally, The GPL applies only when you distribute or convey a program. You can do whatever you want to your software on your computer and you are under no obligation to share it with other users of your computer (or server, or whatever). The AGPL has things to say about that, if the software interacts with a network .. but that’s a topic for a different question.
The FSF takes GPL related questions at licensing@fsf.org — if you are ever in doubt about a particular case and want to make sure you don’t get in trouble, they are rather friendly and happy to answer questions .. even if you are making non-free software. They like it when people take some effort to ensure they follow the license appropriately, which unfortunately doesn’t happen from time to time.
This topic is still just as sensitive as it was in the early 90’s.