After seeing the following [question][1] one of my problems came in mind: I want to couple two different scripts in two different languages. I found a solution for that, and I copied that solution. Unfortunately the same author uses this code for a script which he put under the GPL, but he did not mention the GPL in his example. Can I use the connection (pipe-construction) in a non-free script, even if the script he uses this code is under the GPL? Edit: I want to combine python and ruby, and I used the code from this [page][2]. Later I found out that he wrote a script licensed under the GPL using the same technique. [1]: http://programmers.stackexchange.com/questions/81705/rewriting-gpl-code-to-change-license [2]: http://www.decalage.info/en/python/ruby_bridge