A Repository with 44 Years of Unix Evolution

Summary

A Repository with 44 Years of Unix Evolution Abstract The evolution of the Unix operating system is made available as a version-control repository, covering the period from its inception in 1972 as a five thousand line kernel, to 2015 as a widely-used 26 million line system. The repository contains 659 thousand commits and 2306 merges. The repository employs the commonly used Git system for its storage, and is hosted on the popular GitHub archive. It has been created by synthesizing with custom software 24 snapshots of systems developed at Bell Labs, Berkeley University, and the 386BSD team, two legacy repositories, and the modern repository of the open source FreeBSD system. In total, 850 individual contributors are identified, the early ones through primary research. The data set can be used for empirical research in software engineering, information systems, and software archaeology. 1 Introduction The Unix operating system stands out as a major engineering breakthrough due to its exemplary design, its numerous technical contributions, its development model, and its widespread use. The design of the Unix programming environment has been characterized as one offering unusual simplicity, power, and elegance [1]. On the technical side, features that can be directly attributed to Unix or were popularized by it include [2]: the portable implementation of the kernel in a high level language; a hierarchical file system; compatible file, device, networking, and inter-process I/O; the pipes and filters architecture; virtual file systems; and the shell as a user-selectable regular process. A large community contributed software to Unix from its early days [3], [4,pp. 65-72]. This community grew immensely over time and worked using what are now termed open source software development methods [5,pp. 440-442]. Unix and its intellectual descendants have also helped the spread of the C and C++ programming languages, parser and lexical analyzer generators (yacc, lex), document p...