Do you have to pay for GNU GPL software that is "for sale"? [closed]_问答_开发者

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I've seen some software (a Joomla component, to be exact) for sale on a web site. The web site says it is licensed under the GNU GPL2. However it also says you need to pay for every site you use the software on (with bulk discounts).

I know it's perfectly acceptable to sell software under the GPL, however the license implies that the source code must be distributed at no cost.

So is this a legitimate use of the GPL, or is it violating the license? Is it legal to download the software for free (say, from Bittorrent) and use it as I wish?

Here is a FAQ from the GNU site. I think it answers your question:

Does the GPL allow me to sell copies of the program for money?

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.)

http://www.gnu.org/licenses/gpl-faq.html#DoesTheGPLAllowMoney

Further more:

If I distribute GPL'd software for a fee, am I required to also make it available to the public without a charge?

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.

For GPL software, the source code must be distributed with the binary version or upon request to anyone who legally obtains the binary version.

Ergo, if you didn't buy the product from them, they are under no obligation to give you the source code.

The obvious flip side to this is that anyone who DOES legitimately get the source code is free to redistribute it as they please.

From my understanding distributing it on bittorrent would be redistribution which is permitted under the GPL without limitation (however Trademarks etc could still be violated!) This is how projects like CentOS work - they remove the trademarks, rebuild and then redistribute - and this is perfectly legal.

The company themselves are under no obligation to release source code unless they distribute the software to you.

So your options are:

Get it from someone else (who redistributes it under the GPL)
Purchase the product from the company - they'll give you the source code

I would personally suggest the latter option because it supports companies that support the GPL!

One question is whether the author wrote all the software or used any pre-existing GPLed software. If the person on the web site owns the copyright completely, then the web site may impose any conditions, including those incompatible with the GPL. Of course, releasing it under the GPL gives you some rights by itself. In particular, you can't redistribute without the source code, but you can make copies and use them.

The above practice is generally considered unfriendly by Free and Open Source Software advocates. Since it's not really honest to advertise GPLv2 and not deliver everything necessary, I'd advise being careful about the product. People who deliberately misrepresent things in advertising are likely to be selling shoddy software.

If the software contains pre-existing GPLed components, and the author didn't come to other terms with the copyright holders, then the GPL applies in full. The distributor has to provide source code (either with the executable or on request at nominal cost) and may not impose restrictions not allowed by the GPL.

There's also the possibility that the author released under GPLv2 without actually understanding the license. This happens from time to time, and frequently the FSF will quietly work with companies on getting into compliance.

In either case, it's perfectly fine to sell the software. If somebody else has the software including the source, they can redistribute freely, and it's perfectly legal for you to get it from them.

This is obviously a very simple business trick that relies on the naivity of the purchaser. It is obvious that, if the component is GPL, you can get it from any other user (bittorrent, file sharing), redistribute it and even resell it (but keep it GPL).

It is also very obvious that, if there's no other source to find/get it from, if you purchase, there is absolutely no need to pay multiple times for it. You just need to buy it once, and re-use it on all of the websites that you wish.

Even if it has some source of protection, the source code is open, so you can easily remove that protection.

Just out of curiousity, can you please give the name/website of the Joomla! component?