The code commits of the Unix operating system from the software’s inception in the 70s as 2.5 thousand lines of code to its 30 million line of code in 2018 is now stored on GitHub @ dspinellis/unix-history-repo. The repo includes half a million commits, and over two thousand code merges. Browsing the code commits is a fascinating peek into the evolution of Unix. The operating system that gave us the popular shell commands we use every day, the living legend C language, the Linux system that powers most if not all tech around the world. Unix survives today in the FreeBSD system at the heart of the Apple operating system. Most of all, it kicked off the collaboration of people coding across the globe.
More details about the project is at this link Diomidis Spinellis - A Repository of Unix History and Evolution