I-Publish V1.05 Code serial key or number

“GPL” stands for “General Public License”. The most widespread such license is the GNU General Public License, or GNU GPL for short. This can be further shortened to “GPL”, when it is understood that the GNU GPL is the one intended.

Not at all—there are many other free software licenses. We have an incomplete list. Any license that provides the user certain specific freedoms is a free software license.

Using the GNU GPL will require that all the released improved versions be free software. This means you can avoid the risk of having to compete with a proprietary modified version of your own work. However, in some special situations it can be better to use a more permissive license.

Most GNU software packages use the GNU GPL, but there are a few GNU programs (and parts of programs) that use looser licenses, such as the Lesser GPL. When we do this, it is a matter of strategy.

Anyone can release a program under the GNU GPL, but that does not make it a GNU package.

Making the program a GNU software package means explicitly contributing to the GNU Project. This happens when the program's developers and the GNU Project agree to do it. If you are interested in contributing a program to the GNU Project, please write to <maintainers@gnu.org>.

You should report it. First, check the facts as best you can. Then tell the publisher or copyright holder of the specific GPL-covered program. If that is the Free Software Foundation, write to <license-violation@gnu.org>. Otherwise, the program's maintainer may be the copyright holder, or else could tell you how to contact the copyright holder, so report it to the maintainer.

A crucial aspect of free software is that users are free to cooperate. It is absolutely essential to permit users who wish to help each other to share their bug fixes and improvements with other users.

Some have proposed alternatives to the GPL that require modified versions to go through the original author. As long as the original author keeps up with the need for maintenance, this may work well in practice, but if the author stops (more or less) to do something else or does not attend to all the users' needs, this scheme falls down. Aside from the practical problems, this scheme does not allow users to help each other.

Sometimes control over modified versions is proposed as a means of preventing confusion between various versions made by users. In our experience, this confusion is not a major problem. Many versions of Emacs have been made outside the GNU Project, but users can tell them apart. The GPL requires the maker of a version to place his or her name on it, to distinguish it from other versions and to protect the reputations of other maintainers.

The GPL does not require you to release your modified version, or any part of it. You are free to make modifications and use them privately, without ever releasing them. This applies to organizations (including companies), too; an organization can make a modified version and use it internally without ever releasing it outside the organization.

But if you release the modified version to the public in some way, the GPL requires you to make the modified source code available to the program's users, under the GPL.

Thus, the GPL gives permission to release the modified program in certain ways, and not in other ways; but the decision of whether to release it is up to you.

Yes.

No. The GPL gives a person permission to make and redistribute copies of the program if and when that person chooses to do so. That person also has the right not to choose to redistribute the program.

If you choose to provide source through a written offer, then anybody who requests the source from you is entitled to receive it.

If you commercially distribute binaries not accompanied with source code, the GPL says you must provide a written offer to distribute the source code later. When users non-commercially redistribute the binaries they received from you, they must pass along a copy of this written offer. This means that people who did not get the binaries directly from you can still receive copies of the source code, along with the written offer.

The reason we require the offer to be valid for any third party is so that people who receive the binaries indirectly in that way can order the source code from you.

Section 2 says that modified versions you distribute must be licensed to all third parties under the GPL. “All third parties” means absolutely everyone—but this does not require you to do anything physically for them. It only means they have a license from you, under the GPL, for your version.

You are not required to claim a copyright on your changes. In most countries, however, that happens automatically by default, so you need to place your changes explicitly in the public domain if you do not want them to be copyrighted.

Whether you claim a copyright on your changes or not, either way you must release the modified version, as a whole, under the GPL (if you release your modified version at all).

Under copyright law, translation of a work is considered a kind of modification. Therefore, what the GPL says about modified versions applies also to translated versions. The translation is covered by the copyright on the original program.

If the original program carries a free license, that license gives permission to translate it. How you can use and license the translated program is determined by that license. If the original program is licensed under certain versions of the GNU GPL, the translated program must be covered by the same versions of the GNU GPL.

You can do that, if you can figure out which part is the public domain part and separate it from the rest. If code was put in the public domain by its developer, it is in the public domain no matter where it has been.

Yes, the GPL allows everyone to do this. The right to sell copies is part of the definition of free software. Except in one special situation, there is no limit on what price you can charge. (The one exception is the required written offer to provide source code that must accompany binary-only release.)

Yes. You can charge any fee you wish for distributing a copy of the program. Under GPLv2, if you distribute binaries by download, you must provide “equivalent access” to download the source—therefore, the fee to download source may not be greater than the fee to download the binary. If the binaries being distributed are licensed under the GPLv3, then you must offer equivalent access to the source code in the same way through the same place at no further charge.

No. In fact, a requirement like that would make the program nonfree. If people have to pay when they get a copy of a program, or if they have to notify anyone in particular, then the program is not free. See the definition of free software.

The GPL is a free software license, and therefore it permits people to use and even redistribute the software without being required to pay anyone a fee for doing so.

You can charge people a fee to get a copy from you. You can't require people to pay you when they get a copy from someone else.

No. However, if someone pays your fee and gets a copy, the GPL gives them the freedom to release it to the public, with or without a fee. For example, someone could pay your fee, and then put her copy on a web site for the general public.

No. The GPL says that anyone who receives a copy from you has the right to redistribute copies, modified or not. You are not allowed to distribute the work on any more restrictive basis.

If someone asks you to sign an NDA for receiving GPL-covered software copyrighted by the FSF, please inform us immediately by writing to license-violation@fsf.org.

If the violation involves GPL-covered code that has some other copyright holder, please inform that copyright holder, just as you would for any other kind of violation of the GPL.

No. The GPL says that your modified versions must carry all the freedoms stated in the GPL. Thus, anyone who receives a copy of your version from you has the right to redistribute copies (modified or not) of that version. You may not distribute any version of the work on a more restrictive basis.

Yes. For instance, you can accept a contract to develop changes and agree not to release your changes until the client says ok. This is permitted because in this case no GPL-covered code is being distributed under an NDA.

You can also release your changes to the client under the GPL, but agree not to release them to anyone else unless the client says ok. In this case, too, no GPL-covered code is being distributed under an NDA, or under any additional restrictions.

The GPL would give the client the right to redistribute your version. In this scenario, the client will probably choose not to exercise that right, but does have the right.

You can certainly get credit for the work. Part of releasing a program under the GPL is writing a copyright notice in your own name (assuming you are the copyright holder). The GPL requires all copies to carry an appropriate copyright notice.

No, this is not permitted under the terms of the GPL. While we recognize that proper citation is an important part of academic publications, citation cannot be added as an additional requirement to the GPL. Requiring citation in research papers which made use of GPLed software goes beyond what would be an acceptable additional requirement under section 7(b) of GPLv3, and therefore would be considered an additional restriction under Section 7 of the GPL. And copyright law does not allow you to place such a requirement on the output of software, regardless of whether it is licensed under the terms of the GPL or some other license.

Including a copy of the license with the work is vital so that everyone who gets a copy of the program can know what their rights are.

It might be tempting to include a URL that refers to the license, instead of the license itself. But you cannot be sure that the URL will still be valid, five years or ten years from now. Twenty years from now, URLs as we know them today may no longer exist.

The only way to make sure that people who have copies of the program will continue to be able to see the license, despite all the changes that will happen in the network, is to include a copy of the license in the program.

Just putting a copy of the GNU GPL in a file in your repository does not explicitly state that the code in the same repository may be used under the GNU GPL. Without such a statement, it's not entirely clear that the permissions in the license really apply to any particular source file. An explicit statement saying that eliminates all doubt.

A file containing just a license, without a statement that certain other files are covered by that license, resembles a file containing just a subroutine which is never called from anywhere else. The resemblance is not perfect: lawyers and courts might apply common sense and conclude that you must have put the copy of the GNU GPL there because you wanted to license the code that way. Or they might not. Why leave an uncertainty?

This statement should be in each source file. A clear statement in the program's README file is legally sufficient as long as that accompanies the code, but it is easy for them to get separated. Why take a risk of uncertainty about your code's license?

This has nothing to do with the specifics of the GNU GPL. It is true for any free license.

You should put a notice at the start of each source file, stating what license it carries, in order to avoid risk of the code's getting disconnected from its license. If your repository's README says that source file is under the GNU GPL, what happens if someone copies that file to another program? That other context may not show what the file's license is. It may appear to have some other license, or no license at all (which would make the code nonfree).

Adding a copyright notice and a license notice at the start of each source file is easy and makes such confusion unlikely.

This has nothing to do with the specifics of the GNU GPL. It is true for any free license.

If a whole software package contains very little code—less than 300 lines is the benchmark we use—you may as well use a lax permissive license for it, rather than a copyleft license like the GNU GPL. (Unless, that is, the code is specially important.) We recommend the Apache License 2.0 for such cases.

The preamble and instructions are integral parts of the GNU GPL and may not be omitted. In fact, the GPL is copyrighted, and its license permits only verbatim copying of the entire GPL. (You can use the legal terms to make another license but it won't be the GNU GPL.)

The preamble and instructions add up to some 1000 words, less than 1/5 of the GPL's total size. They will not make a substantial fractional change in the size of a software package unless the package itself is quite small. In that case, you may as well use a simple all-permissive license rather than the GNU GPL.

In order to combine two programs (or substantial parts of them) into a larger work, you need to have permission to use both programs in this way. If the two programs' licenses permit this, they are compatible. If there is no way to satisfy both licenses at once, they are incompatible.

For some licenses, the way in which the combination is made may affect whether they are compatible—for instance, they may allow linking two modules together, but not allow merging their code into one module.

If you just want to install two separate programs in the same system, it is not necessary that their licenses be compatible, because this does not combine them into a larger work.

It means that the other license and the GNU GPL are compatible; you can combine code released under the other license with code released under the GNU GPL in one larger program.

All GNU GPL versions permit such combinations privately; they also permit distribution of such combinations provided the combination is released under the same GNU GPL version. The other license is compatible with the GPL if it permits this too.

GPLv3 is compatible with more licenses than GPLv2: it allows you to make combinations with code that has specific kinds of additional requirements that are not in GPLv3 itself. Section 7 has more information about this, including the list of additional requirements that are permitted.

If you do this, your program won't be fully usable in a free environment. If your program depends on a nonfree library to do a certain job, it cannot do that job in the Free World. If it depends on a nonfree library to run at all, it cannot be part of a free operating system such as GNU; it is entirely off limits to the Free World.

So please consider: can you find a way to get the job done without using this library? Can you write a free replacement for that library?

If the program is already written using the nonfree library, perhaps it is too late to change the decision. You may as well release the program as it stands, rather than not release it. But please mention in the README that the need for the nonfree library is a drawback, and suggest the task of changing the program so that it does the same job without the nonfree library. Please suggest that anyone who thinks of doing substantial further work on the program first free it from dependence on the nonfree library.

Note that there may also be legal issues with combining certain nonfree libraries with GPL-covered free software. Please see the question on GPL software with GPL-incompatible libraries for more information.

Both versions of the GPL have an exception to their copyleft, commonly called the system library exception. If the GPL-incompatible libraries you want to use meet the criteria for a system library, then you don't have to do anything special to use them; the requirement to distribute source code for the whole program does not include those libraries, even if you distribute a linked executable containing them.

The criteria for what counts as a "system library" vary between different versions of the GPL. GPLv3 explicitly defines "System Libraries" in section 1, to exclude it from the definition of "Corresponding Source." GPLv2 deals with this issue slightly differently, near the end of section 3.

If you want your program to link against a library not covered by the system library exception, you need to provide permission to do that. Below are two example license notices that you can use to do that; one for GPLv3, and the other for GPLv2. In either case, you should put this text in each file to which you are granting this permission.

Only the copyright holders for the program can legally release their software under these terms. If you wrote the whole program yourself, then assuming your employer or school does not claim the copyright, you are the copyright holder—so you can authorize the exception. But if you want to use parts of other GPL-covered programs by other authors in your code, you cannot authorize the exception for them. You have to get the approval of the copyright holders of those programs.

When other people modify the program, they do not have to make the same exception for their code—it is their choice whether to do so.

If the libraries you intend to link with are nonfree, please also see the section on writing Free Software which uses nonfree libraries.

If you're using GPLv3, you can accomplish this goal by granting an additional permission under section 7. The following license notice will do that. You must replace all the text in brackets with text that is appropriate for your program. If not everybody can distribute source for the libraries you intend to link with, you should remove the text in braces; otherwise, just remove the braces themselves.

Copyright (C)

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, see <https://www.gnu.org/licenses>.

Additional permission under GNU GPL version 3 section 7

If you modify this Program, or any covered work, by linking or combining it with (or a modified version of that library), containing parts covered by the terms of , the licensors of this Program grant you additional permission to convey the resulting work. {Corresponding Source for a non-source form of such a combination shall include the source code for the parts of used as well as that of the covered work.}

If you're using GPLv2, you can provide your own exception to the license's terms. The following license notice will do that. Again, you must replace all the text in brackets with text that is appropriate for your program. If not everybody can distribute source for the libraries you intend to link with, you should remove the text in braces; otherwise, just remove the braces themselves.

Copyright (C)

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, see <https://www.gnu.org/licenses>.

Linking statically or dynamically with other modules is making a combined work based on . Thus, the terms and conditions of the GNU General Public License cover the whole combination.

In addition, as a special exception, the copyright holders of give you permission to combine with free software programs or libraries that are released under the GNU LGPL and with code included in the standard release of under the (or modified versions of such code, with unchanged license). You may copy and distribute such a system following the terms of the GNU GPL for and the licenses of the other code concerned{, provided that you include the source code of that other code when and as the GNU GPL requires distribution of source code}.

Note that people who make modified versions of are not obligated to grant this special exception for their modified versions; it is their choice whether to do so. The GNU General Public License gives permission to release a modified version without this exception; this exception also makes it possible to release a modified version which carries forward this exception.

Under the Berne Convention, everything written is automatically copyrighted from whenever it is put in fixed form. So you don't have to do anything to “get” the copyright on what you write—as long as nobody else can claim to own your work.

However, registering the copyright in the US is a very good idea. It will give you more clout in dealing with an infringer in the US.

The case when someone else might possibly claim the copyright is if you are an employee or student; then the employer or the school might claim you did the job for them and that the copyright belongs to them. Whether they would have a valid claim would depend on circumstances such as the laws of the place where you live, and on your employment contract and what sort of work you do. It is best to consult a lawyer if there is any possible doubt.

If you think that the employer or school might have a claim, you can resolve the problem clearly by getting a copyright disclaimer signed by a suitably authorized officer of the company or school. (Your immediate boss or a professor is usually NOT authorized to sign such a disclaimer.)

Many universities nowadays try to raise funds by restricting the use of the knowledge and information they develop, in effect behaving little different from commercial businesses. (See “The Kept University”, Atlantic Monthly, March 2000, for a general discussion of this problem and its effects.)

If you see any chance that your school might refuse to allow your program to be released as free software, it is best to raise the issue at the earliest possible stage. The closer the program is to working usefully, the more temptation the administration might feel to take it from you and finish it without you. At an earlier stage, you have more leverage.

So we recommend that you approach them when the program is only half-done, saying, “If you will agree to releasing this as free software, I will finish it.” Don't think of this as a bluff. To prevail, you must have the courage to say, “My program will have liberty, or never be born.”

See the page of GPL instructions.

The GNU GPL does not give users permission to attach other licenses to the program. But the copyright holder for a program can release it under several different licenses in parallel. One of them may be the GNU GPL.

The license that comes in your copy, assuming it was put in by the copyright holder and that you got the copy legitimately, is the license that applies to your copy.

To release a nonfree program is always ethically tainted, but legally there is no obstacle to your doing this. If you are the copyright holder for the code, you can release it under various different non-exclusive licenses at various times.

Strictly speaking, the GPL is a license from the developer for others to use, distribute and change the program. The developer itself is not bound by it, so no matter what the developer does, this is not a “violation” of the GPL.

However, if the developer does something that would violate the GPL if done by someone else, the developer will surely lose moral standing in the community.

No, because the public already has the right to use the program under the GPL, and this right cannot be withdrawn.

Yes, because the copyright on the editors and tools does not cover the code you write. Using them does not place any restrictions, legally, on the license you use for your code.

Some programs copy parts of themselves into the output for technical reasons—for example, Bison copies a standard parser program into its output file. In such cases, the copied text in the output is covered by the same license that covers it in the source code. Meanwhile, the part of the output which is derived from the program's input inherits the copyright status of the input.

As it happens, Bison can also be used to develop nonfree programs. This is because we decided to explicitly permit the use of the Bison standard parser program in Bison output files without restriction. We made the decision because there were other tools comparable to Bison which already permitted use for nonfree programs.

Yes, you do. “Fair use” is use that is allowed without any special permission. Since you don't need the developers' permission for such use, you can do it regardless of what the developers said about it—in the license or elsewhere, whether that license be the GNU GPL or any other free software license.

Note, however, that there is no world-wide principle of fair use; what kinds of use are considered “fair” varies from country to country.

If the program is written by US federal government employees in the course of their employment, it is in the public domain, which means it is not copyrighted. Since the GNU GPL is based on copyright, such a program cannot be released under the GNU GPL. (It can still be free software, however; a public domain program is free.)

However, when a US federal government agency uses contractors to develop software, that is a different situation. The contract can require the contractor to release it under the GNU GPL. (GNU Ada was developed in this way.) Or the contract can assign the copyright to the government agency, which can then release the software under the GNU GPL.

Yes. If the improvements are written by US government employees in the course of their employment, then the improvements are in the public domain. However, the improved version, as a whole, is still covered by the GNU GPL. There is no problem in this situation.

If the US government uses contractors to do the job, then the improvements themselves can be GPL-covered.

No. Linking a GPL covered work statically or dynamically with other modules is making a combined work based on the GPL covered work. Thus, the terms and conditions of the GNU General Public License cover the whole combination. See also What legal issues come up if I use GPL-incompatible libraries with GPL software?

For the purpose of complying with the LGPL (any extant version: v2, v2.1 or v3):

(1) If you statically link against an LGPLed library, you must also provide your application in an object (not necessarily source) format, so that a user has the opportunity to modify the library and relink the application.

(2) If you dynamically link against an LGPLed library already present on the user's computer, you need not convey the library's source. On the other hand, if you yourself convey the executable LGPLed library along with your application, whether linked with statically or dynamically, you must also convey the library's sources, in one of the ways for which the LGPL provides.

In general this is legally impossible; copyright law does not give you any say in the use of the output people make from their data using your program. If the user uses your program to enter or convert her own data, the copyright on the output belongs to her, not you. More generally, when a program translates its input into some other form, the copyright status of the output inherits that of the input it was generated from.

So the only way you have a say in the use of the output is if substantial parts of the output are copied (more or less) from text in your program. For instance, part of the output of Bison (see above) would be covered by the GNU GPL, if we had not made an exception in this specific case.

You could artificially make a program copy certain text into its output even if there is no technical reason to do so. But if that copied text serves no practical purpose, the user could simply delete that text from the output and use only the rest. Then he would not have to obey the conditions on redistribution of the copied text.

The output of a program is not, in general, covered by the copyright on the code of the program. So the license of the code of the program does not apply to the output, whether you pipe it into a file, make a screenshot, screencast, or video.

The exception would be when the program displays a full screen of text and/or art that comes from the program. Then the copyright on that text and/or art covers the output. Programs that output audio, such as video games, would also fit into this exception.

If the art/music is under the GPL, then the GPL applies when you copy it no matter how you copy it. However, fair use may still apply.

Keep in mind that some programs, particularly video games, can have artwork/audio that is licensed separately from the underlying GPLed game. In such cases, the license on the artwork/audio would dictate the terms under which video/streaming may occur. See also: Can I use the GPL for something other than software?

The GPL says that the whole combined program has to be released under the GPL. So your module has to be available for use under the GPL.

But you can give additional permission for the use of your code. You can, if you wish, release your module under a license which is more lax than the GPL but compatible with the GPL. The license list page gives a partial list of GPL-compatible licenses.

Yes, because the program actually links to the library. As such, the terms of the GPL apply to the entire combination. The software modules that link with the library may be under various GPL compatible licenses, but the work as a whole must be licensed under the GPL. See also: What does it mean to say a license is “compatible with the GPL”?

When the interpreter just interprets a language, the answer is no. The interpreted program, to the interpreter, is just data; a free software license like the GPL, based on copyright law, cannot limit what data you use the interpreter on. You can run it on any data (interpreted program), any way you like, and there are no requirements about licensing that data to anyone.

However, when the interpreter is extended to provide “bindings” to other facilities (often, but not necessarily, libraries), the interpreted program is effectively linked to the facilities it uses through these bindings. So if these facilities are released under the GPL, the interpreted program that uses them must be released in a GPL-compatible way. The JNI or Java Native Interface is an example of such a binding mechanism; libraries that are accessed in this way are linked dynamically with the Java programs that call them. These libraries are also linked with the interpreter. If the interpreter is linked statically with these libraries, or if it is designed to link dynamically with these specific libraries, then it too needs to be released in a GPL-compatible way.

Another similar and very common case is to provide libraries with the interpreter which are themselves interpreted. For instance, Perl comes with many Perl modules, and a Java implementation comes with many Java classes. These libraries and the programs that call them are always dynamically linked together.

A consequence is that if you choose to use GPLed Perl modules or Java classes in your program, you must release the program in a GPL-compatible way, regardless of the license used in the Perl or Java interpreter that the combined Perl or Java program will run on.

You may link your program to these libraries, and distribute the compiled program to others. When you do this, the runtime libraries are “System Libraries” as GPLv3 defines them. That means that you don't need to worry about including their source code with the program's Corresponding Source. GPLv2 provides a similar exception in section 3.

You may not distribute these libraries in compiled DLL form with the program. To prevent unscrupulous distributors from trying to use the System Library exception as a loophole, the GPL says that libraries can only qualify as System Libraries as long as they're not distributed with the program itself. If you distribute the DLLs with the program, they won't be eligible for this exception anymore; then the only way to comply with the GPL would be to provide their source code, which you are unable to do.

It is possible to write free programs that only run on Windows, but it is not a good idea. These programs would be “trapped” by Windows, and therefore contribute zero to the Free World.

Because it imposes a specific requirement that is not in the GPL; namely, the requirement on advertisements of the program. Section 6 of GPLv2 states:

You may not impose any further restrictions on the recipients' exercise of the rights granted herein.

GPLv3 says something similar in section 10. The advertising clause provides just such a further restriction, and thus is GPL-incompatible.

The revised BSD license does not have the advertising clause, which eliminates the problem.

It depends on how the main program invokes its plug-ins. If the main program uses fork and exec to invoke plug-ins, and they establish intimate communication by sharing complex data structures, or shipping complex data structures back and forth, that can make them one single combined program. A main program that uses simple fork and exec to invoke plug-ins and does not establish intimate communication between them results in the plug-ins being a separate program.

If the main program dynamically links plug-ins, and they make function calls to each other and share data structures, we believe they form a single combined program, which must be treated as an extension of both the main program and the plug-ins. If the main program dynamically links plug-ins, but the communication between them is limited to invoking the ‘main’ function of the plug-in with some options and waiting for it to return, that is a borderline case.

Using shared memory to communicate with complex data structures is pretty much equivalent to dynamic linking.

Please see this question for determining when plug-ins and a main program are considered a single combined program and when they are considered separate works.

If the main program and the plugins are a single combined program then this means you must license the plug-in under the GPL or a GPL-compatible free software license and distribute it with source code in a GPL-compliant way. A main program that is separate from its plug-ins makes no requirements for the plug-ins.

Please see this question for determining when plug-ins and a main program are considered a single combined program and when they are considered separate programs.

If they form a single combined program this means that combination of the GPL-covered plug-in with the nonfree main program would violate the GPL. However, you can resolve that legal problem by adding an exception to your plug-in's license, giving permission to link it with the nonfree main program.

See also the question I am writing free software that uses a nonfree library.

Please see this question for determining when plug-ins and a main program are considered a single combined program and when they are considered separate programs.

If they form a single combined program then the main program must be released under the GPL or a GPL-compatible free software license, and the terms of the GPL must be followed when the main program is distributed for use with these plug-ins.

However, if they are separate works then the license of the plug-in makes no requirements about the main program.

See also the question I am writing free software that uses a nonfree library.

Not exactly. It means you must release your program under a license compatible with the GPL (more precisely, compatible with one or more GPL versions accepted by all the rest of the code in the combination that you link). The combination itself is then available under those GPL versions.

You can ask, but most authors will stand firm and say no. The idea of the GPL is that if you want to include our code in your program, your program must also be free software. It is supposed to put pressure on you to release your program in a way that makes it part of our community.

You always have the legal alternative of not using our code.

Linux (the kernel in the GNU/Linux operating system) is distributed under GNU GPL version 2. Does distributing a nonfree driver meant to link with Linux violate the GPL?

Yes, this is a violation, because effectively this makes a larger combined work. The fact that the user is expected to put the pieces together does not really change anything.

Each contributor to Linux who holds copyright on a substantial part of the code can enforce the GPL and we encourage each of them to take action against those distributing nonfree Linux-drivers.

Add this text to the license notice of each file in the package, at the end of the text that says the file is distributed under the GNU GPL:

Linking ABC statically or dynamically with other modules is making a combined work based on ABC. Thus, the terms and conditions of the GNU General Public License cover the whole combination.

As a special exception, the copyright holders of ABC give you permission to combine ABC program with free software programs or libraries that are released under the GNU LGPL and with independent modules that communicate with ABC solely through the ABCDEF interface. You may copy and distribute such a system following the terms of the GNU GPL for ABC and the licenses of the other code concerned, provided that you include the source code of that other code when and as the GNU GPL requires distribution of source code and provided that you do not modify the ABCDEF interface.

Note that people who make modified versions of ABC are not obligated to grant this special exception for their modified versions; it is their choice whether to do so. The GNU General Public License gives permission to release a modified version without this exception; this exception also makes it possible to release a modified version which carries forward this exception. If you modify the ABCDEF interface, this exception does not apply to your modified version of ABC, and you must remove this exception when you distribute your modified version.

This exception is an additional permission under section 7 of the GNU General Public License, version 3 (“GPLv3”)

This exception enables linking with differently licensed modules over the specified interface (“ABCDEF”), while ensuring that users would still receive source code as they normally would under the GPL.

Only the copyright holders for the program can legally authorize this exception. If you wrote the whole program yourself, then assuming your employer or school does not claim the copyright, you are the copyright holder—so you can authorize the exception. But if you want to use parts of other GPL-covered programs by other authors in your code, you cannot authorize the exception for them. You have to get the approval of the copyright holders of those programs.

To answer this question, we would need to see a list of each component that your program uses, the license of that component, and a brief (a few sentences for each should suffice) describing how your library uses that component. Two examples would be:

• To make my software work, it must be linked to the FOO library, which is available under the Lesser GPL.
• My software makes a system call (with a command line that I built) to run the BAR program, which is licensed under “the GPL, with a special exception allowing for linking with QUUX”.

An “aggregate” consists of a number of separate programs, distributed together on the same CD-ROM or other media. The GPL permits you to create and distribute an aggregate, even when the licenses of the other software are nonfree or GPL-incompatible. The only condition is that you cannot release the aggregate under a license that prohibits users from exercising rights that each program's individual license would grant them.

Where's the line between two separate programs, and one program with two parts? This is a legal question, which ultimately judges will decide. We believe that a proper criterion depends both on the mechanism of communication (exec, pipes, rpc, function calls within a shared address space, etc.) and the semantics of the communication (what kinds of information are interchanged).

If the modules are included in the same executable file, they are definitely combined in one program. If modules are designed to run linked together in a shared address space, that almost surely means combining them into one program.

By contrast, pipes, sockets and command-line arguments are communication mechanisms normally used between two separate programs. So when they are used for communication, the modules normally are separate programs. But if the semantics of the communication are intimate enough, exchanging complex internal data structures, that too could be a basis to consider the two parts as combined into a larger program.

No, the analysis of whether they are a single work or an aggregate is unchanged by the involvement of containers.

Our lawyers have told us that to be in the best position to enforce the GPL in court against violators, we should keep the copyright status of the program as simple as possible. We do this by asking each contributor to either assign the copyright on contributions to the FSF, or disclaim copyright on contributions.

We also ask individual contributors to get copyright disclaimers from their employers (if any) so that we can be sure those employers won't claim to own the contributions.

Of course, if all the contributors put their code in the public domain, there is no copyright with which to enforce the GPL. So we encourage people to assign copyright on large code contributions, and only put small changes in the public domain.

If you want to make an effort to enforce the GPL on your program, it is probably a good idea for you to follow a similar policy. Please contact <licensing@gnu.org> if you want more information.

It is possible to make modified versions of the GPL, but it tends to have practical consequences.

You can legally use the GPL terms (possibly modified) in another license provided that you call your license by another name and do not include the GPL preamble, and provided you modify the instructions-for-use at the end enough to make it clearly different in wording and not mention GNU (though the actual procedure you describe may be similar).

If you want to use our preamble in a modified license, please write to <licensing@gnu.org> for permission. For this purpose we would want to check the actual license requirements to see if we approve of them.

Although we will not raise legal objections to your making a modified license in this way, we hope you will think twice and not do it. Such a modified license is almost certainly incompatible with the GNU GPL, and that incompatibility blocks useful combinations of modules. The mere proliferation of different free software licenses is a burden in and of itself.

Rather than modifying the GPL, please use the exception mechanism offered by GPL version 3.

You are allowed to sell copies of the modified program commercially, but only under the terms of the GNU GPL. Thus, for instance, you must make the source code available to the users of the program as described in the GPL, and they must be allowed to redistribute and modify it as described in the GPL.

These requirements are the condition for including the GPL-covered code you received in a program of your own.

You can apply the GPL to any kind of work, as long as it is clear what constitutes the “source code” for the work. The GPL defines this as the preferred form of the work for making changes in it.

However, for manuals and textbooks, or more generally any sort of work that is meant to teach a subject, we recommend using the GFDL rather than the GPL.

See this article for details. It works as designed, intended, and expected.

Yes. Y was required to release its version under the GNU GPL, as a consequence of basing it on X's version V1. Nothing required Y to agree to any other license for its code. Therefore, X must get Y's permission before releasing that code under another license.

You cannot incorporate GPL-covered software in a proprietary system. The goal of the GPL is to grant everyone the freedom to copy, redistribute, understand, and modify a program. If you could incorporate GPL-covered software into a nonfree system, it would have the effect of making the GPL-covered software nonfree too.

A system incorporating a GPL-covered program is an extended version of that program. The GPL says that any extended version of the program must be released under the GPL if it is released at all. This is for two reasons: to make sure that users who get the software get the freedom they should have, and to encourage people to give back improvements that they make.

However, in many cases you can distribute the GPL-covered software alongside your proprietary system. To do this validly, you must make sure that the free and nonfree programs communicate at arms length, that they are not combined in a way that would make them effectively a single program.

The difference between this and “incorporating” the GPL-covered software is partly a matter of substance and partly form. The substantive part is this: if the two programs are combined so that they become effectively two parts of one program, then you can't treat them as two separate programs. So the GPL has to cover the whole thing.

If the two programs remain well separated, like the compiler and the kernel, or like an editor and a shell, then you can treat them as two separate programs—but you have to do it properly. The issue is simply one of form: how you describe what you are doing. Why do we care about this? Because we want to make sure the users clearly understand the free status of the GPL-covered software in the collection.

If people were to distribute GPL-covered software calling it “part of” a system that users know is partly proprietary, users might be uncertain of their rights regarding the GPL-covered software. But if they know that what they have received is a free program plus another program, side by side, their rights will be clear.