GPL-3.0-only or GPL-3.0-or-later?

[TechnologyClassroom]

I am adding a stub page for vimix to the Free Software Directory and I cannot tell if this project is GPL-3.0-only or GPL-3.0-or-later. Can you answer which one it is? The answer would usually go in the license header of source files or in the README file. I could help with a pull request after I know which it is.

[brunoherbelin]

Hi Thanks for the initiative.

The LICENSE file specifies GPL 3.0

I didn't think further if it should be 3.0 only or 3.0 or later: your suggestions are welcome. And yes, I did not have time (nor found the motivation) to add the licensing info on the header of each source files: if you were willing to help it would be greatly appreciated !

[TechnologyClassroom]

I would suggest GPL-3.0-or-later. This ensures compatibility with future versions of the GPL. I use -or-later on all of my GPL code.

Example: GPL-2.0-only and GPL-3.0-* are incompatible, but GPL-2.0-or-later is compatible with GPL-3.0-only and GPL-3.0-or-later.

Once you pick, I can make a PR to the README.

[brunoherbelin]

Ok I see, and agree with you: I'd choose GPL-3.0-or-later Thanks for the suggestion!

I updated the README Something else to change?

I'd gladly accept a pull-request if you'd be willing to help.

[TechnologyClassroom]

What you did is good enough for the most part. If you want to go "all the way", there are a few extra things that can be done following the directions at the very end of the license to craft license headers. A license header for Vimix might look like this (The copyright line would need some modifications, but the dates are correct):

# Vimix - Live video mixer
# **Copyright** (C) 2020-2021 Bruno Herbelin <bruno@email.com>
#
# This program 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.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

This header could go on the README file (without # comments) and also near the top of all source files. Placing it at the top of each source file is a lot of work, but it can be automated. Not everyone does the source file headers, but it allows the license to be easily maintained in the future if a file is picked up by another project.

[prez]

Unnecessary. Take a look at how e.g. coreboot does it: https://github.com/coreboot/coreboot/blob/master/src/northbridge/intel/haswell/acpi.c#L1

Being greeted with this prose every time you open a file to look at the source just makes it harder to work with.

[TechnologyClassroom]

Here is an example with the full headers: https://git.savannah.gnu.org/cgit/coreutils.git/tree/src/cat.c

[brunoherbelin]

Done !