freeglut is intended to be a 100% plug-compatible clone, and is released under the Xfree license. The GLUT (OpenGL Utility Toolkit) is a widely used library for doing window control, keyboard, and mouse input, and other basic functions for OpenGL programs. However, GLUT is not OpenSourced - although it's source code is available under a somewhat ill-defined set of restrictions. Hence, 'freeglut'.
epto is a small library and framework for industrial strength shell script programming with sh. It features convenient error handling, tracing, logging, option handling, documentation template, process level transaction safety (sort of), and more. If one is used to shell programming, it takes less than five minutes of learning to start using it (see the crash course in the README file).