History of Unix and Linux

Location: Bell Labs, part of AT&T (New Jersey), late 1960s through early 1970s

  • Multics, a time sharing system (that is, more than one person could use it at once)
  • Multics had issues and was slowly abandoned
  • Ken Thompson found an old PDP-7. Started to write UNIX.
  • Also, the ed text editor was written. Pronounced e.d. but generally sounded out.
  • This version of UNIX would later be referred to as Research Unix
  • Dennis Ritchie joined him and created the C language (In October 2011, Steve Jobs passed away a week before Dennis Ritchie, but the world mourned Jobs and Ritchie's death went largely unnoticed).

Location: Berkeley, CA (University of California, Berkeley), early to mid 1970s

  • The code for UNIX was not 'free' but low cost and easily shared.
  • Ken Thompson visited Berkeley and helped install Version 6 of UNIX https://en.wikipedia.org/wiki/Berkeley_Software_Distribution.
  • Bill Joy and others contributed heavily (Joy created vi, which Vim descends from).
  • This installation of UNIX would eventually become known as the Berkeley Software Distribution, or BSD.


  • Until its breakup in 1984, AT&T was not allowed to profit off of patents that were not directly related to its telecommunications businesses.
  • This agreement with the US government helped protect the company from charges of monopoly, and as a result, they could not commercialize UNIX.
  • This changed after the breakup. System V UNIX became the standard bearer of commercial UNIX.

Location: Boston, MA (MIT), early 1980s through early 1990s

  • In the late 1970s, Richard Stallman began to notice that software began to become commoditized and as a result, hardware vendors were no longer sharing the code they developed to make their hardware work. During much of his education, software code was not eligible for copyright protection (changed under the Copyright Act of 1976).
  • Stallman, who thrived in a hacker culture (Wikipedia page on Stallman), began to wage battles against this.
  • Stallman created the [GNU project][gnuproject] and philosophy (also the creator of GNU Emacs). The project is an attempt to create a completely free operating system, that was Unix-like, called GNU.
  • By the early 1990s, Stallman and others had developed all the utilities needed to have a full operating system, except for a kernel.
  • This includes the Bash shell, written by Brian Fox.
  • The philosophy includes several propositions that define free software:

The four freedoms, per GNU Project


  1. The freedom to run the program as you wish, for any purpose (freedom 0).
  2. The freedom to study how the program works, and change it so it does your computing as you wish (freedom 1). Access to the source code is a precondition for this.
  3. The freedom to redistribute copies so you can help others (freedom 2).
  4. The freedom to distribute copies of your modified versions to others (freedom 3). By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this.

The Unix wars and the lawsuit

  • Differences in AT&T Unix and BSD Unix arose. The former was aimed at commercialization and the latter aimed at researchers and academics.
  • UNIX Systems Laboratories, Inc. (USL, part of AT&T) sued Berkeley Software Design, Inc. (BSDi, part of the University of California, Berkeley) for copyright and trademark violations.
  • USL ultimately lost the case.

The Rise of Linux, Linus Torvalds, University of Helsinki, Finland

  • On August 25, 1991 (30 years ago), [Linus Torvalds][linustorvalds] announced that he had started working on a free operating system kernel for the 386 CPU architecture and for the specific hard drives that he had. This kernel would later be named Linux.
  • Linux technically refers only to the kernel. An operating system kernel handles startup, devices, memory, resources, etc.
  • His motivation was to learn about OS development but also to have access to a Unix-like system. He already had access to an Unix-like system called MINIX, but MINIX had some technical and copyright restrictions.
  • Torvalds has stated that if a BSD or if GNU Hurd were available, then he may not have created the Linux kernel.
  • But Torvalds and others took the GNU utilities and created what is now called Linux, or GNU/Linux.


  • Soon after Linux development, people would create their own Linux and GNU based operating systems and would distribute.
  • As such, they became referred to as distributions.
  • The two oldest distributions that are still in active development include:
    • Slackware
    • Debian

Short History of BSD

  • Unix version numbers 1-6 eventually led to BSD 1-4.
  • At BSD 4.3, all versions had some AT&T code. Desire to remove this code led to BSD Net/1.
  • All AT&T code was removed by BSD Net/2.
  • BSD Net/2 was ported to the Intel 386 processor. This became 386BSD and was made available a year after the Linux kernel was released, in 1992.
  • 386BSD split into two projects:
    • NetBSD
    • FreeBSd
  • NetBSD split into another project: OpenBSD.
  • All three of these BSDs are still in active development. From a bird's eye point of view, they each have different foci:
    • NetBSD focuses on portability (MacOS, NASA)
    • FreeBSD focuses on wide applicability (WhatsApp, Netflix, PlayStation 4, MacOS)
    • OpenBSD focuses on security (has contributed a number of very important applications)

Note: MacOS is based on [Darwin][puredarwin], is technically UNIX, and is partly based on FreeBSD with some code coming from the other BSDs.

Short History of GNU

  • The GNU Hurd is still being developed, but it's only in the pre-production state. The last release was 0.9 on December 2016. A complete OS based on the GNU Hurd can be downloaded and ran.

Free and Open Source Licenses

  • [GNU General Public License (GPL)][gnugpl]
  • [BSD License][bsdlicense]