No calls to shell, no external binaries executed, just pure [BSD] Makefiles rendering my favorite fractal.bmake (AKA BSD make) is the implementation of make(1) used by BSD operating systems. It does not support basic arithmetic, it doesn t have infinite loops, no floating point support, but I forced it to render a fractal anyways :) . To use BSD make on Linux, search your package manager for bmake , install it, and run `bmake` inside the cloned repo instead of `make`.