[erlang-questions] GNU GPL, MIT, BSD and compatibility

Richard Carlsson <>
Thu Apr 10 10:45:13 CEST 2008


Alceste Scalas wrote:
> The GNU GPL does *not* require that the linked software is released (or
> re-licensed) under the terms of the GNU GPL itself.

Really? Here's what the GPL (v2) says:

"You may modify your copy or copies of the Program or any portion of it, 
thus forming a work based on the Program, and copy and distribute such 
modifications or work under the terms of Section 1 above, provided that you 
also meet all of these conditions:

     a) You must cause the modified files to carry prominent notices stating 
that you changed the files and the date of any change.
     b) You must cause any work that you distribute or publish, that in 
whole or in part contains or is derived from the Program or any part 
thereof, to be licensed as a whole at no charge to all third parties under 
the terms of this License.
     c) [...]"

As far as I can see, this is rather clear: *if* you distribute the derived
work, then all of it *has* to be provided under the GPL ("this License"),
There are some exceptions, such as if you distribute only the parts you have
written:

"These requirements apply to the modified work as a whole. If identifiable 
sections of that work are not derived from the Program, and can be 
reasonably considered independent and separate works in themselves, then 
this License, and its terms, do not apply to those sections when you 
distribute them as separate works. But when you distribute the same sections 
as part of a whole which is a work based on the Program, the distribution of 
the whole must be on the terms of this License, whose permissions for other 
licensees extend to the entire whole, and thus to each and every part 
regardless of who wrote it."

The LGPL differs in that it does not consider code that merely links to your
program to be a derived work. Is that what you meant?

     /Richard





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