Subj : Re: Copyright and addons or comercial GUI for a GPL software
To   : comp.programming
From : Jonathan Bartlett
Date : Fri Aug 05 2005 04:27 pm

> Are there any restrictions in using GPL code in comercial applicatins?

Yes.

> I have seen the Linux Kernel used on a lot of appliances.

That's because the kernel is not linked to the program.

> My intention as I mentioned in an earlier  thread is to design a good
> interface for some GPL applications and to sell this interface. 

Selling is not against the GPL.  Selling under non-GPL licenses is.

> I will
> not charge for the application itself but I think it is fair to charge
> for the interface. The design requires a lot of work for design and
> implementation. 

The amount of work is irrelevant.  What is relevant is whether or not 
your work is considered a derivative work.

If you link to libraries, that is usually considered a derivative work. 
  Static linking definitely is, dynamic linking using headers supplied 
under the GPL also is.  I do not know of the rules for dynamic linking 
without the GPL headers.  However, if you are not linking to the GPL 
work, but merely using it as a separate application, there is no 
problem.  In fact, I know Mathematica does this.  If you look on the CD 
they distribute you will see a source file containing a GPL application 
which they use as a separate, unlinked application but is distributed 
with Mathematica.

As for LGPL libraries, there are other rules.  With those, you are 
allowed to freely dynamically link.  For static linking, there are more 
rules, but basically you have to provide the unlinked versions of both 
your code and the libraries, so the user can upgrade the library and 
relink if he wishes.

Jon
----
Learn to program using Linux assembly language
http://www.cafeshops.com/bartlettpublish.8640017

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