This post gives some hints about how to use a GNU license (GPL, LGPL, AGPL) in a software project.
In case of doubt, please follow the links above. The rest of this post just try to clarify certain points.
Steps about how to adapt the Software to use a GNU License
You may need to update your project to:
- Set project file headers
- Include License File
- Modify Software to display Disclaimer
1. Set Project File Headers
Set header for all project files, including copyright notice, license notice, project name and contact information.
2. Include License File
Include the license file, called conventionally COPYING in GNU project.
3. Modify Software to display Disclaimer
The software should display the disclaimer, for example, in the “About…” dialog. The FSF even recommends to show it on startup.
The disclaimer could be:
Copyright (C) <year> <name of author> 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/>.
Even if the program is run from the command line, it should display the disclaimer.
The FSF proposed that this text to be included in command line programs is:
<program> Copyright (C) <year> <name of author> This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. This is free software, and you are welcome to redistribute it under certain conditions; type `show c' for details.
‘show c’ and ‘show w’ should be adapted to the corresponding interface.
You can read a discussion about what it means on this external link.
How to adapt the Documentation related to a Software to use a GNU License
According to the FSF, documentation should also have a special treatment. Free Document License (FDL) would apply.
You can find more information on this external link.
- GNU; “How to Use GNU Licenses for Your Own Software“; GNU