The UNIX® system is an old operating system, possibly older than many of the readers of this post. However, despite its age, it still has not been open sourced completely. In this post, I will try to detail which parts of which UNIX systems have not yet been open sourced. I will focus on the legal situation in Germany in particular, taking it representative of European law in general – albeit that is a stretch, knowing the diversity of European jurisdictions. Please note that familiarity with basic terms of copyright law is assumed.