Re: GPL and command-line libraries

[Måns Rullgård <mru@inprovide.com>]

Josselin Mouette <joss@debian.org> writes:

> Le mardi 02 novembre 2004 à 21:53 +0100, Wesley W. Terpstra a écrit :
>> Mr. John Wontshare writes a streaming multicast client.
>> To deal with packet loss, he uses my error-correcting library.
>> Without my library, Mr. Wontshare's client can't work at all.
>> Mr. Wontshare's client represents only a small investment of effort and
>> without having had access to my library, he could have never written it.
>> He then distributes his client along with my library to end-users.
>
> If Mr Wontshare's client doesn't work without your software, this is
> what I call a derivative work. Whether it is linked to it using ELF or
> not is irrelevant.

Mr. Wontshare's program *uses* the GPL program, but isn't derived from
it.  See http://www.gnu.org/licenses/gpl-faq.html#MereAggregation.

Further, consider what would happen if someone else created an
application with an interface compatible with the OP's program.  Would
Mr. Wontshare's program then become a derivative this program as well?
A program compatible with the OP's could even be written before Mr.
Wontshare writes his.  Which one is it then derived from?  The only
consistent answer is that it is not derived at all.

-- 
Måns Rullgård
mru@inprovide.com