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Cygwin licensing and redistribution, GPLv2, GPLv3
- From: tom honermann <tom dot honermann at oracle dot com>
- To: cygwin-developers at cygwin dot com
- Date: Thu, 27 Jan 2011 15:57:20 -0800
- Subject: Cygwin licensing and redistribution, GPLv2, GPLv3
I've been looking into Cygwin licensing and redistribution regarding the
Cygwin DLL and various GNU utilities. The current Cygwin license
(http://cygwin.com/licensing.html) states (and I'm paraphrasing) that
programs that use the Cygwin DLL do not need to be licensed under GPLv2
(or compatible) so long as they are distributed with a license that
meets the OSI's open source definition AND that the cygwin DLL is not
distributed with the program. With the release of the GPLv3 license and
subsequent re-licensing, some of the GNU utilities included with the
Cygwin distribution are now GPLv3 (or later). The GPLv2 and GPLv3
licenses are not compatible
(http://www.gnu.org/licenses/gpl-faq.html#v2v3Compatibility). The way I
interpret this, this effectively means that no entity other than RedHat
can distribute GPLv3 GNU utilities dynamically linked with the Cygwin
DLL and include the Cygwin DLL with the GNU utilities (without
additional permissions by RedHat). This also means that no entity other
than RedHat can redistribute the RedHat Cygwin distribution or build
their own Cygwin distribution unless all programs are linked with a
static version of the Cygwin library (again, without additional
permissions by RedHat). Does this sound right? If so, is this an
intentional property of the Cygwin license?
Tom.