> did I just create a derivative work of "ls"? No, output of a program isn't the program itself, so it doesn't fall under copyright[1]. Why would you expect th

> did I just create a derivative work of "ls"? No, output of a program isn't the program itself, so it doesn't fall under copyright[1]. Why would you expect that it would be a derivative work? It should be obvious that e.g. when gcc outputs a compiled program it doesn't automatically become tied to the GPL. The only exception - which is mentioned[2] in the GPL - is if the output of a GPL licensed program is part of the licensed program. (quines, other rare utilities) 2. Basic Permissions. [...] This License explicitly affirms your unlimited permission to run the unmodified Program. The output from running a covered work is covered by this License only if the output, given its content, constitutes a covered work. [...] > would my program that calls [a library derived from GPL licensed program] also be a derivative? Probably[3], but see the FAQ[4] for answers to common situations and a real lawyer for actual legal advice. > does one form of calling create a derivative and the other form not? Correct. They are different. The intent is that the GPL licensed code is still open. Users that receive copies of the new stand-alone executable can exercise their right to examine and modify that code. They can easily replace it with a version they have modified without touching your other programs that merely use the output. [1] https://www.gnu.org/licenses/gpl-faq.html#GPLOutput https://www.gnu.org/licenses/gpl-faq.html#GPLOutput [2] https://www.gnu.org/licenses/gpl-3.0.en.html https://www.gnu.org/licenses/gpl-3.0.en.html [3] https://www.gnu.org/licenses/gpl-faq.html#IfLibraryIsGPL https://www.gnu.org/licenses/gpl-faq.html#IfLibraryIsGPL [4] https://www.gnu.org/licenses/gpl-faq.html https://www.gnu.org/licenses/gpl-faq.html