@jihadjimmy parallel:
Academic tradition requires you to cite works you base your article on.
If you use programs that use GNU Parallel to process data for an article in a
scientific publication, please cite:

<no>

This helps funding further development; AND IT WON'T COST YOU A CENT.
If you pay 10000 EUR you should feel free to use GNU Parallel without citing.

More about funding GNU Parallel and the citation notice:
https://www.gnu.org/software/parallel/parallel_design.html#citation-notice

To silence this citation notice: run 'parallel --citation' once.

Come on: You have run parallel 100001 times. Isn't it about time
you run 'parallel --citation' once to silence the citation notice?


Based off memory, the author claims that citing is part of the licensing requirement, although that doesn't meet any of the options under "7. Additional Terms.", so that's an additional restriction.

https://www.gnu.org/licenses/gpl-faq.html#RequireCitation


Debian has patched the nagging behavior out by default, but I'm not sure about other distros.