What's the case when using software licensed under GPL or LGPL

Question

With everything legal and in line with the ethical questions in software development, is it allowed to use an open source product in my software that I charge a fee for when selling?

Scenario: I've developed an PHP Content Management System (CMS) and use some Linux executables licensed under GPL or LGPL in my CMS to accomplish various tasks like image editing. I'm selling the CMS and also including the executables when I deliver the product.

I do not edit the source code of the GPL software, just using it.

Answer 1

charging a fee is not the critical point of GPL, you can charge fees as high as the mt. everest with stuff covered by the (L)GPL. as soon as the GPL-project "touches" your own stuff in most cases your stuff must be GPL from that point on as well.

the LGPL just mildens the "touch".

eg, lets say you call a system command "foo", which is covered by the GPL, as a standalone process of the OS: thats ok, you are not "really" touching it. but if you are "linking" against a "libfoo" which is convered by the GPL, your stuff becomes GPL as well. if "libfoo" would be LGPL you would be allowed to link against it.

so, it all depends on "i just use it".

read more on the subject over at wikipedia.

Answer 2

IANAL

As long as you supply the source code of any GPL programmes you use on request in as suitable form to anyone you sell or give the software to, you're definately alright (so no, you don't have to release source code to non-customers) . lgpl allows you to link without the distribution clause, but any changes need to be contributed back.

If you 'use' something standalone (say imagemagik) without linking it to your app and your app isn't a derivative work of something which isn't gpl, your software may not need to be released under the GPL

the wikipedia article goes into some level of detail on this and probably explains it better than i can ;)