What can you do with a GPLv2 licensed module or extension can it be modified? [closed]

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I would like to modify a Joomla extension for my own company website but i don't understand something. The extension is under GPLv2 or later License witch i thought meant you are able to change it if you would like but when you open up the file is says it not to be modified isn't that the point of the GPLv2 or later License? Also some files have copy right to such and such person am I able to change those extensions I'm not going to distribute them its just for my company website so how does that work? Also one Joomla's website in says that some are Non-Commercial what does this mean when its a GPLv2? Sorry for so many questions I just don't understand how this works out in the really world.

Answer 1

Go read the licence. In the absence of explicit additional requests (which GPLv2 allows for, provided they don't contradict the terms of the GPLv2) you can modify the code for your own use. So a restriction that you cannot modify the code is in direct contravention of clause 2:

You may modify your copy or copies of the Program or any portion of it,

If the licence for the software states " but when you open up the file is says it not to be modified" then de-facto it cannot be GPLv2. But if it is GPLv2, then de facto it must be modifiable by you.

If you then provide the modified code to anyone else (sell it or give it away), then you must offer it under the terms of the GPLv2 - i.e. you can sell your modified code, but you can't stop your customers from selling it on. But if you don't pass it on to anyone else, then you are not under an obligaton to make it available to everyone.

The extension is under GPLv2 or later License

Eh? This makes no sense. Although UCITA seems to offer this in the US, in practice it is meaningless to enter into an agreement whose terms are unspecified at the time of contract. It's either GPLv2 or it's something else.

Assuming this "licence" is intended to cover the package as a whole, then it is so self-contradictary as to be gibberish.

A bundle of software may include components under different licences (a typical Linux distribution contains software offered under GPLv2, MIT, BSD, Mozila Public Licence, Apache licence, Perl licence, PHP licence, CCDL....).

Answer 2

You are experiencing a permissions problem. GPLv2 code can be modified - your OS however is stopping you from saving or opening the file. My guess is that you are on trying to do this on a linux server and the file doesn't belong to your "user".

A code license is just the legal text about the file - it has no effect on how the file operates or behaves. It isn't a physical security system.

In other news, GPL code can be modified and kept or given away as long as your changes are also released under the GPL. Basically, share and share alike.

Answer 3

To extend on @Xeoncross's answer here are two Joomla.org specific answers relating to GPL and their extensions directory.

1. The Joomla Extensions Directory and the GPL
2. Free and Commercial extensions