Re: gpl3 vs. gpl3+

[Mark H Weaver <mhw@netris.org>]

Alex Kost <alezost@gmail.com> writes:

> I see that only several packages uses 'gpl3' license.  And I don't
> really understand the cases when it should be used instead of 'gpl3+'.
>
> I looked at "aarddict" and "weechat".  They have the same
> COPYING/LICENSE files as <http://www.gnu.org/licenses/gpl.txt>.  So it
> should be gpl3+, right?

The license of a program is determined by the copyright notices in the
files themselves, not by the mere existence of a copy of a license
somewhere in the tarball.

Language like this in the files means gpl3+:

;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.

If the "or (at your option) any later version" language is missing, then
it's just gpl3.

To ease the labor of looking at the copyright notices on every file, I
look at the corresponding Debian copyright file.  Debian tends to do a
fairly thorough job of license checking.  I search for the package using
http://packages.debian.org/<PACKAGE-NAME>, I select a package whose
version number is the same (or quite close) to the one I'm packaging,
and then I select the "Copyright File" link in the "Debian Resources"
section on the right side of the web page.

Also beware that the Debian copyright file only documents licenses on
files that they have not removed.  Just below the "Debian Resources"
section on the right is a section "Download Source Package".  If you see
"DFSG" in the name of the original tarball file, that means that they've
removed files for copyright reasons.

Hope this helps,

      Mark