History of Unix/Linux

• OS: Two meanings
  1. The program that manages the resources of a computer
     • This is the operating system proper
     • In unix/linux terms we call this the kernel.
     • It is the thing that
       • Manages processes (running programs)
       • Manages the file system
       • Maintains security
       • Interacts with devices
  2. The kernel along with all of the associated utilities
     • Shells
     • utilities (ls, awk, sed, more, less, ...)
     • Applications (compilers, editors, ...)
• The same is true of UNIX
  1. Any Operating system that has passed the official conformance tests by the Open Group.
  2. Any Unix like operating system.
• UNIX
  • First developed by Ken Thompson
    • Written in assembly language
    • On a PDP-7
    • The name is a play on an OS he had worked on MULTICX
    • At AT&T
  • Rewritten in PDP-11 assembly language
  • Rewritten in 1973 to be mostly in C
    • C was developed by Dennis Ritchie at AT&T
    • Followed from an earlier language B, which followed from BCPL
    • Designed to provide access to low level memory
    • And to provide constructs that map efficiently to machine instructions
    • It was written to develop OS (UNIX)
  • "Like the UNIX operating system itself, C was designed by professional programmers for their own use."
  • Some UNIX highlights from the book
    • 1971 First Edition: ar, cat, chmod, chown, cp ,dc ,ed, find, ln, ls, mail, mkdir, mv, rm, sh, su who
    • Quick look at man.
      • man subject
      • man -k subject, man -k bc
      • main section title , man 1p bc
    • 1972 Second Edition: installed on 10 machines inside ATT
    • 1973 Third Edition: Included the C compiler and pipes
    • 1973 November Fourth Edition: Written "almost totally" in C
    • 1974 Fifth Edition, installed on more that 50 machines.
    • 1975 Sixth Edition, Distribution outside of AT&T
  • The UNIX Time-Sharing System a paper published in Communications of the ACM, 1974.
    • "Perhaps the most important achievement of UNIX is to demonstrate that a powerful operating system for interactive use need not be expensive either in equipment or in human effort: UNXI can run on hardware costing as little as $40,000 and less than two man years were spent on the main system software"
    • Look at the last page: the fifth most popular program was chess
  • At this time AT&T had a monopoly (The phone system)
    • They were not permitted to sell software.
    • So they provided UNIX to universities at a very low license fee.
    • Many universities took advantage of this
      • Code to use in OS class
      • Platform for OS research and implementation.
      • A low cost interactive multi user operating system.
    • 1979 Seventh Edition
    • awk, make, sed, tar, uucp, sh
    • BSD
      • Thompson spent at year at University of California Berkeley
      • Many additions were created
      • csh, vi , fast berkeley file system, sendmail, ...
      • This became the Berkeley Software Distribution (BSD)
      • BSD 2 was just a series of utilities and patches to UNIX
      • BSD 3 was a full release
      • 4.X was a full release with 4.2 becoming a standard of sorts.
        • This became a basis for SunOS and others.
      • You were required to get a UNIX license, then you could get BSD on tapes :)
    • In 1982 AT&T was broken up by federal government pressure
      • 7 regional bell systems
      • Unix went with Bell Labs, at AT&T
      • And started to sell UNIX, and closed the source
      • UNIX System V (SVR4) became somewhat of a standard
      • This led Richard Stallman to start the GNU project
        • GNU : GNU's Not Unix
        • Free software movement
        • Free Software Manifesto
        • Upset that you could no longer study and modify the code
        • Oh and "Software sellers want to divide the users and conquer them, making each user agree not to share with others. I refuse to break solidarity with other users in this way. I cannot in good conscience sign a nondisclosure agreement or a software license agreement."
        • And concludes "In the long run, making programs free is a step toward the postscarcity world, where nobody will have to work very hard just to make a living. People will be free to devote themselves to activities that are fun, such as programming, after spending the necessary ten hours a week on required tasks such as legislation, family counseling, robot repair and asteroid prospecting. There will be no need to be able to make a living from programming."
      • At the same time, there were many professional versions of UNIX developed
        • AIX - ibm
        • Sun - SunOS and later SOLARIS
        • HPUX - hp
        • Digital - Ultrix, OSF/1, Dec Unix
        • SGI - IRIX
    • UNIX was sold to NOVEL
    • In 1993 NOVEL transferred to UNIX license to X/Open Consortium
    • Which merged with the OSF to form the Open Group.
    • In 1995 Novel sold the System V license to SCO
    • And then there were lawsuits.
  • Linux Kernel produced by Linus Torvalds
    • 1991
    • A Finnish CS student.
    • Released under the GNU license
    • Used many of the GNU tools.
    • Working with Minux an os teaching tool.
  • BSD continued as a unix like os as well
    • But lawsuits and threats from various parties sort of stiffeled it.
  •