http://tilde.club is one unmodified unix server on the Internet Several hundred people have accounts It was launched at the end of September 2014 Tilde.Club is also an emerging, mutually supportive community of dozens hundreds thousands of people launching similar servers.
Unix Operating System (OS) Tutorial - Learning fundamentals of UNIX in simple and easy steps : A beginner's tutorial containing complete knowledge of Unix Korn and Bourne Shell and Programming, Utilities, File System, Directories, Memory Management, Special Variables, vi editor, Processes
The MacPorts Project is an open-source community initiative to design an easy-to-use system for compiling, installing, and upgrading either command-line, X11 or Aqua based open-source software on the Mac OS X operating system.