Experimental Physics and
Industrial Control System

"J. Lewis Muir" <[email protected]> · Thu, 23 Oct 2014 18:42:26 -0500

On 10/23/14 2:58 AM, Johnson, Andrew N. wrote:
>> On Oct 23, 2014, at 00:07, J. Lewis Muir <[email protected]> wrote:
>> See:
>>
>>  http://www.gnu.org/licenses/gpl-faq.html#GPLAndPlugins
>>
>> To me, that supports what I said.
>
> Read the following FAQ points as well, there are subtle distinctions
> between whether your main application is GPL or your plugin is GPL,
> and I think the example you pointed to was for a non-GPL plugin to a
> GPL application.

Hi, Andrew.

Hmm...I don't see the subtle distinctions.  I see distinctions for
linking and whatnot, but I don't see distinctions for the "fork and
exec" case.  I very much so respect your opinion on this, so I'd really
like to understand.  There are three FAQ questions that talk about
plug-ins and they all start with a paragraph that says there are no
special requirements if the program uses fork and exec to invoke the
plug-ins.  Here are the three questions and the first paragraph of each
answer:

* If I write a plug-in to use with a GPL-covered program, what
  requirements does that impose on the licenses I can use for
  distributing my plug-in?

  It depends on how the program invokes its plug-ins. If the program
  uses fork and exec to invoke plug-ins, then the plug-ins are separate
  programs, so the license for the main program makes no requirements
  for them.

* Can I apply the GPL when writing a plug-in for a non-free program?

  If the program uses fork and exec to invoke plug-ins, then the
  plug-ins are separate programs, so the license for the main program
  makes no requirements for them. So you can use the GPL for a plug-in,
  and there are no special requirements.

* Can I release a non-free program that's designed to load a GPL-covered
  plug-in?

  It depends on how the program invokes its plug-ins. For instance, if
  the program uses only simple fork and exec to invoke and communicate
  with plug-ins, then the plug-ins are separate programs, so the license
  of the plug-in makes no requirements about the main program.

So, I'm not getting it.  What am I missing?!  Thanks for your patience.

Regards,

Lewis

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System