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Is it necessarily if a software released under both of LGPL3 && GPL3 terms have to include both license header notice top of each file?

Or just put GPL header notice? or simply put LGPL3 license text in some file like COPYING.LESSER ?


I am the copyright holder of the project!

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2 Answers

up vote 2 down vote accepted

Case 1. When this is your own code:

In general, you only need to put Copyright notice in the work (here source code). The license doesn't require a mention.

For example, for Apache license doesn't need any such reference.

However, GPL specifically wants that you reference GPL License word inside each source code.

the process involves adding two elements to each source file of your program: a copyright notice (such as “Copyright 1999 Terry Jones”), and a statement of copying permission, saying that the program is distributed under the terms of the GNU General Public License

from: http://www.gnu.org/licenses/gpl-howto.html

In this case, to avoid the interpretation that the code is uncondtionally GPL'ed, it makes sense that you either specify additional clause like

"subject to terms and condition provided in LICENSE.txt"

Case 2: If you are modifying the other person code:

You cannot do -dual license, and also you cannot modify anything on the source that provides licensing information.

BTW: There is one simpler alternative that is obvious.

If you make identical copy of the code which has no mention of GPL at all and you use that copy for the Commercial or alternative license.

But this might just be too cumbersome.

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Yes, this is my own code, so just create two files COPYING && COPYING.LESSER and mention them at top of the each file? –  Huckleberry Finn Feb 24 '12 at 15:32
Yes. But most important thing is to specify that GPL license is subject to terms and condition which means that source is other license separately. –  Dipan Mehta Feb 24 '12 at 15:36
Should specify the exact version ? because the #gnu guyz was so serious about this stuff! –  Huckleberry Finn Feb 24 '12 at 15:40
I think you mean GPL vs. GLPv3? Yes. Basically, GPLv3 is just a different license from GPL (which is first version). There is no concept of Versions. So if you think you want to put GPLv3 - but mention only GPL in the source file - there is a confusion which they want to avoid. So put GPLv3 or GPLv2 depending on what you want. –  Dipan Mehta Feb 24 '12 at 15:42
The usage is okay but LGPL is completely different from GPL (all versions). LGPL will allow people to use your code as binary only linkage without modification in closed source (potentially commercial usage). So you should use that only if you really want to use LGPL. In general, if you are fine with LGPL license, there is no point in dual license. Other than binary linking - all other aspects of GPL and LGPL are same. –  Dipan Mehta Feb 24 '12 at 15:56
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I am not a lawyer (IANAL), but I don't think it is necessary to add license text at the top of each file. Include the licenses in an external file and distribute this file with your software.

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As How to use GNU licenses for your own software says, it's better to do, and even provide header notice example, but didn't provide any for dual-license –  Huckleberry Finn Feb 24 '12 at 15:04
It probably is better, but I don't think it's necessary to maintain copyright. Again, I am not an expert. –  Bernard Feb 24 '12 at 15:35
I agree with that. In doubt, the normal copyright prevents anyone from using it. An open source license is only there to open it up, it will never close the usage down. As such there should be no need to specify the license in every file, as they are protected anyway. If a license in a more central place then allows the usage under certain terms, then that should be fine enough. (imo) –  poke Feb 24 '12 at 15:49
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