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History of Unix

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   Main article: Unix

   CAPTION: Unix

   Unix history-simple.svg
   Evolution of Unix and Unix-like systems
   Developer Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas
   McIlroy, and Joe Ossanna at Bell Labs
   Written in C and Assembly language
   OS family Unix
   Working state Current
   Source model Historically closed source, now some Unix projects (BSD
   family and Illumos) are open sourced.
   Initial release 1969; 52 years ago (1969)
   Available in English
   Kernel type Monolithic
   Default user interface Command-line interface & Graphical (X Window
   System)
   License Proprietary
   Official website opengroup.org/unix

   The history of Unix dates back to the mid-1960s when the Massachusetts
   Institute of Technology, AT&T Bell Labs, and General Electric were
   jointly developing an experimental time-sharing operating system called
   Multics for the GE-645 mainframe.^[1] Multics introduced many
   innovations, but had many problems.

   Bell Labs, frustrated by the size and complexity of Multics but not the
   aims, slowly pulled out of the project. Their last researchers to leave
   Multics - Ken Thompson, Dennis Ritchie, Doug McIlroy, and Joe Ossanna
   among others^[2] - decided to redo the work on a much smaller
   scale.^[3] In 1979, Dennis Ritchie described their vision for Unix:^[3]

     What we wanted to preserve was not just a good environment in which
     to do programming, but a system around which a fellowship could
     form. We knew from experience that the essence of communal
     computing, as supplied by remote-access, time-shared machines, is
     not just to type programs into a terminal instead of a keypunch, but
     to encourage close communication.

   [ ]

Contents

     * 1 1969
     * 2 1970s
     * 3 1980s
          + 3.1 Standardization and the Unix wars
     * 4 1990s
     * 5 2000s
     * 6 See also
     * 7 References
     * 8 Further reading
     * 9 External links

1969[edit]

   In the late 1960s, Bell Labs was involved in a project with MIT and
   General Electric to develop a time-sharing system, called Multiplexed
   Information and Computing Service (Multics), allowing multiple users to
   access a mainframe simultaneously. Dissatisfied with the project's
   progress, Bell Labs management ultimately withdrew.

   Ken Thompson, a programmer in the Labs' computing research department,
   had worked on Multics. He decided to write his own operating system.
   While he still had access to the Multics environment, he wrote
   simulations for the new file and paging system^[clarification needed]
   on it. He also programmed a game called Space Travel, but it needed a
   more efficient and less expensive machine to run on, and eventually he
   found a little-used Digital Equipment Corporation PDP-7 at Bell
   Labs.^[4]^[5] On the PDP-7, in 1969, a team of Bell Labs researchers
   led by Thompson and Ritchie, including Rudd Canaday, implemented a
   hierarchical file system, the concepts of computer processes and device
   files, a command-line interpreter, and some small utility programs,
   modeled on the corresponding features in Multics, but simplified.^[3]
   The resulting system, much smaller and simpler than Multics, was to
   become Unix. In about a month's time, in August 1969, Thompson had
   implemented a self-hosting operating system with an assembler, editor
   and shell, using a GECOS machine for bootstrapping.^[6]

   Douglas McIlroy then ported TMG compiler-compiler to PDP-7 assembly,
   creating the first high-level language running on Unix. Thompson used
   this tool to develop the first version of his B programming
   language.^[3]

1970s[edit]

   Ken Thompson (sitting) and Dennis Ritchie working together at a PDP-11
   Ken Thompson and Dennis Ritchie
   Version 7 Unix for the PDP-11, running in SIMH
   Unix time-sharing at the University of Wisconsin, 1978

   The new operating system was initially without organizational backing,
   and also without a name. At this stage, the new operating system was a
   singletasking operating system,^[3] not a multitasking one such as
   Multics. The name Unics (Uniplexed Information and Computing Service,
   pronounced as "eunuchs"), a pun on Multics (Multiplexed Information and
   Computer Services), was initially suggested for the project in 1970.
   Brian Kernighan claims the coining for himself, and adds that "no one
   can remember" who came up with the final spelling Unix.^[7] Dennis
   Ritchie and Doug McIlroy also credit Kernighan.^[3]^[8]

   When the Computing Sciences Research Center wanted to use Unix on a
   machine larger than the PDP-7, while another department needed a word
   processor, Thompson and Ritchie added text processing capabilities to
   Unix and received funding for a PDP-11/20.^[5] For the first time in
   1970, the Unix operating system was officially named and ran on the
   PDP-11/20. A text-formatting program called roff and a text editor were
   added. All three were written in PDP-11/20 assembly language. Bell Labs
   used this initial text-processing system, consisting of Unix, roff, and
   the editor, for text processing of patent applications. Roff soon
   evolved into troff, the first electronic publishing program with full
   typesetting capability.

   As the system grew in complexity and the research team wanted more
   users, the need for a manual grew apparent. The UNIX Programmer's
   Manual was published on 3 November 1971; commands were documented in
   the "man page" format that is still used, offering terse reference
   information about usage as well as bugs in the software, and listing
   the authors of programs to channel questions to them.^[8]

   After other Bell Labs departments purchased DEC PDP-11s, they also
   chose to run Unix instead of DEC's own operating system. By Version 4
   it was widely used within the laboratory and a Unix Support Group was
   formed, helping the operating system survive by formalizing its
   distribution.^[5]^[8]

   In 1973, Version 4 Unix was rewritten in the higher-level language C,
   contrary to the general notion at the time that an operating system's
   complexity and sophistication required it to be written in assembly
   language.^[9]^[5] The C language appeared as part of Version 2.
   Thompson and Ritchie were so influential on early Unix that McIlroy
   estimated that they wrote and debugged about 100,000 lines of code that
   year, stating that "[their names] may safely be assumed to be attached
   to almost everything not otherwise attributed".^[8] Although assembly
   did not disappear from the man pages until Version 8,^[8] the migration
   to C suggested portability of the software, requiring only a relatively
   small amount of machine-dependent code to be replaced when porting Unix
   to other computing platforms. Version 4 Unix, however, still had
   considerable PDP-11-dependent code and was not suitable for porting.
   The first port to other platform was made five years later (1978) for
   Interdata 8/32.^[10]

   The Unix operating system was first presented formally to the outside
   world at the 1973 Symposium on Operating Systems Principles, where
   Ritchie and Thompson delivered a paper. This led to requests for the
   system, but under a 1956 consent decree in settlement of an antitrust
   case, the Bell System (the parent organization of Bell Labs) was
   forbidden from entering any business other than "common carrier
   communications services", and was required to license any patents it
   had upon request.^[6] Unix could not, therefore, be turned into a
   product. Bell Labs instead shipped the system for the cost of media and
   shipping.^[6] Ken Thompson quietly began answering requests by shipping
   out tapes and disks, each accompanied by - according to legend - a note
   signed, "Love, Ken".^[11]

   In 1973, AT&T released Version 5 Unix and licensed it to educational
   institutions, and licensed 1975's Version 6 to companies for the first
   time.^[12] While commercial users were rare because of the US$20,000
   (equivalent to $95,028 in 2019) cost, the latter was the most widely
   used version into the early 1980s. Anyone could purchase a license, but
   the terms were very restrictive; licensees only received the source
   code, on an as-is basis.^[12] The licenses also included the
   machine-dependent parts of the kernel, written in PDP-11 assembly
   language. Copies of the Lions' Commentary on UNIX 6th Edition, with
   Source Code circulated widely, which led to considerable use of Unix as
   an educational example. The first meeting of Unix users took place in
   New York in 1974, attracting a few dozen people; this would later grow
   into the USENIX organization. The importance of the user group stemmed
   from the fact that Unix was entirely unsupported by AT&T.^[6]

   Versions of the Unix system were determined by editions of its user
   manuals;^[12] for example, "Fifth Edition UNIX" and "UNIX Version 5"
   have both been used to designate the same version. The Bell Labs
   developers did not think in terms of "releases" of the operating
   system, instead using a model of continuous development, and sometimes
   distributing tapes with patches (without AT&T lawyers' approval).^[6]
   Development expanded, adding the concept of pipes, which led to the
   development of a more modular code base, and quicker development
   cycles. Version 5, and especially Version 6, led to a plethora of
   different Unix versions both inside and outside Bell Labs, including
   PWB/UNIX and the first commercial Unix, IS/1.

   Unix still only ran on DEC systems.^[12] As more of the operating
   system was rewritten in C (and the C language extended to accommodate
   this), portability also increased; in 1977, Bell Labs procured an
   Interdata 8/32 with the aim of porting Unix to a computer that was as
   different from the PDP-11 as possible, making the operating system more
   machine-independent in the process. Unix next ran as a guest operating
   system inside a VM/370 hypervisor at Princeton. Simultaneously, a group
   at the University of Wollongong ported Unix to the similar Interdata
   7/32.^[13] Target machines of further Bell Labs ports for research and
   AT&T-internal use included an Intel 8086-based computer (with
   custom-built MMU) and the UNIVAC 1100.^[14]^[5]

   In May 1975, ARPA documented the benefits of the Unix time-sharing
   system which "presents several interesting capabilities" as an ARPA
   network mini-host in RFC 681.

   In 1978, UNIX/32V was released for DEC's then new VAX system. By this
   time, over 600 machines were running Unix in some form. Version 7 Unix,
   the last version of Research Unix to be released widely, was released
   in 1979. In Version 7, the number of system calls was only around 50,
   although later Unix and Unix-like systems would add many more:^[15]

     Version 7 of the Research UNIX System provided about 50 system
     calls, 4.4BSD provided about 110, and SVR4 had around 120. The exact
     number of system calls varies depending on the operating system
     version. More recent systems have seen incredible growth in the
     number of supported system calls. Linux 3.2.0 has 380 system calls
     and FreeBSD 8.0 has over 450.

   A microprocessor port of Unix, to the LSI-11, was completed in
   1978,^[16] and an Intel 8086 version was reported to be "in progress"
   the same year.^[13] The first microcomputer versions of Unix, and
   Unix-like operating systems like Whitesmiths' Idris, appeared in the
   late 1970s.^[12]

1980s[edit]

   The DEC VT100 terminal, widely used for Unix timesharing
   USENIX 1984 Summer speakers. USENIX was founded in 1975, focusing
   primarily on the study and development of Unix and similar systems.
   The X Window System with twm and a number of core X applications

   Bell developed multiple versions of Unix for internal use, such as CB
   UNIX (with improved support for databases) and PWB/UNIX, the
   "Programmer's Workbench", aimed at large groups of programmers. It
   advertised the latter version, as well as 32V and V7, stating that
   "more than 800 systems are already in use outside the Bell System" in
   1980,^[17] and "more than 2000" the following year.^[18] Research Unix
   versions 8, 9, and 10 were developed through the 1980s but were only
   released to a few universities, though they did generate papers
   describing the new work. This research focus then shifted to the
   development of Plan 9 from Bell Labs, a new portable distributed
   system.

   Because the company widely and inexpensively licensed Unix,^[19] by the
   early 1980s thousands of people used Unix at AT&T and elsewhere, and as
   computer science students moved from universities into companies they
   wanted to continue to use it. Observers began to see Unix as a
   potential universal operating system, suitable for all computers. Less
   than 20,000 lines of code - almost all in C - composed the Unix kernel
   as of 1983, and more than 75% was not machine-dependent. By that year
   Unix or a Unix-like system was available for at least 16 different
   processors and architectures from about 60 vendors; BYTE noted that
   computer companies "may support other [operating] systems, but a Unix
   implementation always happens to be available",^[5]^[12]^[20] and that
   DEC and IBM supported Unix as an alternative to their proprietary
   operating systems.^[21]

   Microcomputer Unix became commercially available in 1980, when Onyx
   Systems released its Zilog Z8000-based C8002^[12] and Microsoft
   announced its first Unix for 16-bit microcomputers called Xenix, which
   the Santa Cruz Operation (SCO) ported to the 8086 processor in 1983.
   Other companies began to offer commercial versions of Unix for their
   own minicomputers and workstations. Many of these new Unix flavors were
   developed from the System V base under a license from AT&T; others were
   based on BSD. One of the leading developers of BSD, Bill Joy, went on
   to co-found Sun Microsystems in 1982 and created SunOS for its
   workstations.

   AT&T announced UNIX System III - based on Version 7, and PWB - in 1981.
   Licensees could sell binary sublicenses for as little as US$100
   (equivalent to $281.22 in 2019), which observers believed indicated
   that AT&T now viewed Unix as a commercial product.^[12] This also
   included support for the VAX. AT&T continued to issue licenses for
   older Unix versions. To end the confusion between all its differing
   internal versions, AT&T combined them into UNIX System V Release 1.
   This introduced a few features such as the vi editor and curses from
   the Berkeley Software Distribution of Unix developed at the University
   of California, Berkeley Computer Systems Research Group. This also
   included support for the Western Electric 3B series computers. AT&T
   provided support for System III and System V through the Unix Support
   Group (USG), and these systems were sometimes referred to as USG
   Unix.^[citation needed]

   In 1983, the U.S. Department of Justice settled its second antitrust
   case against AT&T, causing the breakup of the Bell System. This
   relieved AT&T of the 1956 consent decree that had prevented the company
   from commercializing Unix. AT&T promptly introduced Unix System V into
   the market. The newly created competition nearly destroyed the
   long-term viability of Unix, because it stifled the free exchanging of
   source code and led to fragmentation and incompatibility.^[11] The GNU
   Project was founded in the same year by Richard Stallman.

   Since the newer commercial UNIX licensing terms were not as favorable
   for academic use as the older versions of Unix, the Berkeley
   researchers continued to develop BSD as an alternative to UNIX System
   III and V. Many contributions to Unix first appeared in BSD releases,
   notably the C shell with job control (modelled on ITS). Perhaps the
   most important aspect of the BSD development effort was the addition of
   TCP/IP network code to the mainstream Unix kernel. The BSD effort
   produced several significant releases that contained network code:
   4.1cBSD, 4.2BSD, 4.3BSD, 4.3BSD-Tahoe ("Tahoe" being the nickname of
   the Computer Consoles Inc. Power 6/32 architecture that was the first
   non-DEC release of the BSD kernel), Net/1, 4.3BSD-Reno (to match the
   "Tahoe" naming, and that the release was something of a gamble), Net/2,
   4.4BSD, and 4.4BSD-lite. The network code found in these releases is
   the ancestor of much TCP/IP network code in use today, including code
   that was later released in AT&T System V UNIX and early versions of
   Microsoft Windows. The accompanying Berkeley sockets API is a de facto
   standard for networking APIs and has been copied on many platforms.

   During this period, many observers expected that UNIX, with its
   portability, rich capabilities, and support from companies like DEC and
   IBM, was likely to become an industry-standard operating system for
   microcomputers.^[21]^[22] Citing its much smaller software library and
   installed base than that of MS-DOS and the IBM PC, others expected that
   customers would prefer personal computers on local area networks to
   Unix multiuser systems.^[23] Microsoft planned to make Xenix MS-DOS's
   multiuser successor;^[12] by 1983 a Xenix-based Altos 586 with 512 KB
   RAM and 10 MB hard drive cost US$8,000 (equivalent to $20,536 in
   2019).^[24] BYTE reported that the Altos "under moderate load
   approaches DEC VAX performance for most tasks that a user would
   normally invoke", while other computers from Sun and MASSCOMP were much
   more expensive but equaled the VAX. The magazine added that both PC/IX
   and Venix on the IBM PC outperformed Venix on the PDP-11/23.^[21]
   uNETix, a commercial microcomputer Unix, implemented the first Unix
   color windowing system.^[citation needed]

   In 1986, Computerworld wrote that "Until very recently, almost no one
   associated Unix with corporate data processing. [...] the operating
   system traveled almost exclusively in academic and technical circles
   ... But now -- almost entirely because of strenuous efforts by AT&T --
   some people are beginning to perceive Unix as a viable option for large
   commercial installations." Unix became commercially available for the
   mainframe via Amdahl UTS in 1981, and now IBM started offering Unix as
   IX/370 and VM/IX. The total installed base of Unix, however, remained
   small at some 230,000 machines.^[25]^:37,44

   Despite its academic reputation - InfoWorld stated in 1989, "Until
   recently, Unix conjured up visions of long-haired bearded technoids
   stuck in the bowels of an R&D lab, coding software until the wee hours
   of the morning" - the increasing power of microcomputers in the late
   1980s, and in particular the introduction of the 32-bit Intel 80386,
   caused Unix to "explode" in popularity for business applications;
   Xenix, 386/ix, and other Unix systems for the PC-compatible market
   competed with OS/2 in terms of networking, multiuser support,
   multitasking, and MS-DOS compatibility.^[26] The beginning in 1984 of
   the annual Unix Expo trade show in New York reflected the growing
   commercial presence of Unix.^[27]

   During this time a number of vendors including Digital Equipment, Sun,
   Addamax and others began building trusted versions of UNIX for high
   security applications, mostly designed for military and law enforcement
   applications.

Standardization and the Unix wars[edit]

   Main article: Unix wars

   A problem that plagued Unix in this period was the multitude of
   implementations, based on either System V, BSD, or what Poul-Henning
   Kamp later described as a "more or less competently executed"
   combination of the two,^[28] usually with home-grown extensions to the
   base systems from AT&T or Berkeley.^[25]^:38 Xenix was effectively a
   third lineage, being based on the earlier System III.^[29] The rivalry
   between vendors was called the Unix wars; customers soon demanded
   standardization.^[29]

   AT&T responded by issuing a standard, the System V Interface Definition
   (SVID, 1985), and required conformance for operating systems to be
   branded "System V". In 1984, several European computer vendors
   established the X/Open consortium with the goal of creating an open
   system specification based on Unix (and eventually the SVID).^[30] Yet
   another standardization effort was the IEEE's POSIX specification
   (1988), designed as a compromise API readily implemented on both BSD
   and System V platforms. POSIX was soon^[when?] mandated by the United
   States government for many of its own systems.^[citation needed]

   In the spring of 1988, AT&T took the standardization a step further.
   First, it collaborated with SCO to merge System V and Xenix into System
   V/386.^[29] Next, it sought collaboration with Sun Microsystems (vendor
   of the 4.2BSD derivative SunOS and its Network File System) to merge
   System V, BSD/SunOS and Xenix into a single unified Unix, which would
   become System V Release 4. AT&T and Sun, as UNIX International (UI),
   acted independently of X/Open and drew ire from other vendors, which
   started the Open Software Foundation to work on their own unified Unix,
   OSF/1, ushering in a new phase of the Unix wars.^[29]

1990s[edit]

   Unix workstations of the 1990s, including those made by DEC, HP, SGI,
   and Sun
   The Common Desktop Environment (CDE) was widely used on Unix
   workstations.

   The Unix wars continued into the 1990s, but turned out to be less
   serious of a threat than it originally looked: AT&T and Sun went their
   own ways after System V.4, while OSF/1's schedule slipped behind.^[29]
   By 1993, most commercial vendors changed their variants of Unix to be
   based on System V with many BSD features added. The creation of the
   Common Open Software Environment (COSE) initiative that year, by the
   major players in Unix, marked the end of the most notorious phase of
   the Unix wars, and was followed by the merger of UI and OSF in 1994.
   The new combined entity retained the OSF name and stopped work on
   OSF/1. By that time the only vendor using it was Digital Equipment
   Corporation, which continued its own development, rebranding their
   product Digital UNIX in early 1995. POSIX became the unifying standard
   for Unix systems (and some other operating systems).^[29]

   Meanwhile, the BSD world saw its own developments. The group at
   Berkeley moved its operating system toward POSIX compliance and
   released a stripped-down version of its networking code, supposedly
   without any code that was the property of AT&T. In 1991, a group of BSD
   developers (Donn Seeley, Mike Karels, Bill Jolitz, and Trent Hein) left
   the University of California to found Berkeley Software Design, Inc.
   (BSDi), which sold a fully functional commercial version of BSD Unix
   for the Intel platform, which they advertised as free of AT&T code.
   They ran into legal trouble when AT&T's Unix subsidiary sued BSDi for
   copyright infringement and various other charges in relation to BSD;
   subsequently, the University of California countersued.^[31] Shortly
   after it was founded, Bill Jolitz left BSDi to pursue distribution of
   386BSD, the free software ancestor of FreeBSD, OpenBSD, and NetBSD.

   Shortly after UNIX System V Release 4 was produced, AT&T sold all its
   rights to UNIX to Novell. Dennis Ritchie likened this sale to the
   Biblical story of Esau selling his birthright for the mess of
   pottage.^[32] Novell developed its own version, UnixWare, merging its
   NetWare with UNIX System V Release 4. Novell tried to use this as a
   marketing tool against Windows NT, but their core markets suffered
   considerably. It also quickly settled the court battles with BSDi and
   Berkeley.^[31]

   In 1993, Novell decided to transfer the UNIX trademark and
   certification rights to the X/Open Consortium.^[33] In 1996, X/Open
   merged with OSF, creating the Open Group. Various standards by the Open
   Group now define what is and what is not a UNIX operating system,
   notably the post-1998 Single UNIX Specification.

   In 1995, the business of administering and supporting the existing UNIX
   licenses, plus rights to further develop the System V code base, were
   sold by Novell to the Santa Cruz Operation.^[34] Whether Novell also
   sold the copyrights would later become the subject of litigation (see
   below).

   With the legal troubles between AT&T/Novell and the University of
   California over, the latter did two more releases of BSD before
   disbanding its Computer Systems Research Group in 1995. The BSD code
   lived on, however, in its free derivatives and in what Garfinkel et al.
   call a second generation of commercial Unix systems, based on BSD. The
   first exponent of these was BSDi's offering, popular at internet
   service providers but eventually not successful enough to sustain the
   company.^[29]^:22 The other main exponent would be Apple Computer.

   In 1997, Apple sought a new foundation for its Macintosh operating
   system and chose NeXTSTEP, an operating system developed by NeXT. The
   core operating system, which was based on BSD and the Mach kernel, was
   renamed Darwin after Apple acquired it. The deployment of Darwin in Mac
   OS X makes it, according to a statement made by an Apple employee at a
   USENIX conference, the most widely used Unix-based system in the
   desktop computer market.^[citation needed]

   Meanwhile, Unix got competition from the copyleft Linux kernel, a
   reimplementation of Unix from scratch, using parts of the GNU project
   that had been underway since the mid-1980s. Work on Linux began in 1991
   by Linus Torvalds; in 1998, a confidential memo at Microsoft stated,
   "Linux is on track to eventually own the x86 UNIX market," and further
   predicted, "I believe that Linux - moreso than NT - will be the biggest
   threat to SCO in the near future."^[35]

2000s[edit]

   History of computing
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   Computer science
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   Timeline of computing
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   In 2000, SCO sold its entire UNIX business and assets to Caldera
   Systems, which later changed its name to The SCO Group.

   The bursting of the dot-com bubble (2001-03) led to significant
   consolidation of versions of Unix. Of the many commercial variants of
   Unix that were born in the 1980s, only Solaris, HP-UX, and AIX were
   still doing relatively well in the market, though SGI's IRIX persisted
   for quite some time. Of these, Solaris had the largest market share in
   2005.^[36]

   In 2003, the SCO Group started legal action against various users and
   vendors of Linux. SCO had alleged that Linux contained copyrighted Unix
   code now owned by the SCO Group. Other allegations included
   trade-secret violations by IBM, or contract violations by former Santa
   Cruz customers who had since converted to Linux. However, Novell
   disputed the SCO Group's claim to hold copyright on the UNIX source
   base. According to Novell, SCO (and hence the SCO Group) are
   effectively franchise operators for Novell, which also retained the
   core copyrights, veto rights over future licensing activities of SCO,
   and 95% of the licensing revenue. The SCO Group disagreed with this,
   and the dispute resulted in the SCO v. Novell lawsuit. On 10 August
   2007, a major portion of the case was decided in Novell's favor (that
   Novell had the copyright to UNIX, and that the SCO Group had improperly
   kept money that was due to Novell). The court also ruled that "SCO is
   obligated to recognize Novell's waiver of SCO's claims against IBM and
   Sequent". After the ruling, Novell announced they have no interest in
   suing people over Unix and stated, "We don't believe there is Unix in
   Linux".^[37]^[38]^[39] SCO successfully got the 10th Circuit Court of
   Appeals to partially overturn this decision on 24 August 2009 which
   sent the lawsuit back to the courts for a jury trial.^[40]^[41]^[42]

   On 30 March 2010, following a jury trial, Novell, and not The SCO
   Group, was "unanimously [found]" to be the owner of the UNIX and
   UnixWare copyrights.^[43] The SCO Group, through bankruptcy trustee
   Edward Cahn, decided to continue the lawsuit against IBM for causing a
   decline in SCO revenues.^[44] On March 1, 2016, SCO's lawsuit against
   IBM was dismissed with prejudice.
   See also: SCO-Linux controversies

   In 2005, Sun Microsystems released the bulk of its Solaris system code
   (based on UNIX System V Release 4) into an open source project called
   OpenSolaris. New Sun OS technologies, notably the ZFS file system, were
   first released as open source code via the OpenSolaris project. Soon
   afterwards, OpenSolaris spawned several non-Sun distributions. In 2010,
   after Oracle acquired Sun, OpenSolaris was officially discontinued, but
   the development of derivatives continued.

   Since the early 2000s, Linux is the leading Unix-like operating system,
   with other variants of Unix (apart from macOS) having only a negligible
   market share (see Usage share of operating systems).

See also[edit]

     * Comparison of operating systems
     * List of Unix systems
     * Operating systems timeline
     * Plan 9 from Bell Labs

References[edit]

    1. ^ Stuart, Brian L. (2009). Principles of operating systems: design
       & applications. Boston, Massachusetts: Thompson Learning. p. 23.
       ISBN 978-1-4188-3769-3.
    2. ^ "In the Beginning: Unix at Bell Labs".
    3. ^ ^a ^b ^c ^d ^e ^f Ritchie, Dennis M. (1984). "The Evolution of
       the Unix Time-sharing System". AT&T Bell Laboratories Technical
       Journal. 63 (6 Part 2): 1577-93.
       doi:10.1002/j.1538-7305.1984.tb00054.x. Archived from the original
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Further reading[edit]

   Books.

     *

   Kernighan, Brian W. (2019). UNIX: A History and a Memoir. Independently
   published. ISBN 978-1695978553.



   Salus, Peter H. (1994). A Quarter Century of UNIX. Addison Wesley.
   ISBN 978-0-201-54777-1.

   Television.

     *

   "UNIX". The Computer Chronicles. 1985.

     "Unix". The Computer Chronicles. 1989.

   Talks.

     *

   Ken Thompson (2019). "VCF East 2019 -- Brian Kernighan interviews Ken
   Thompson" (Interview).

     Dr Marshall Kirk McKusick (2006). History of the Berkeley Software
   Distributions (three one-hour lectures).

External links[edit]

   Look up Unix in Wiktionary, the free dictionary.

     * The UNIX System, at The Open Group.
     * The Creation of the UNIX Operating System
     * The Unix Heritage Society
          + The Unix Tree: files from historic releases
     * History of Unix at Curlie
     * The Unix 1st Edition Manuals.
     * 1982 film about Unix featuring Dennis Ritchie, Ken Thompson, Brian
       Kernighan, Alfred Aho, and more
     * Video: VCF East 2019 -- Brian Kernighan interviews Ken Thompson
     * A History of UNIX before Berkeley: UNIX Evolution: 1975-1984
     * audio bsdtalk170 - Marshall Kirk McKusick at DCBSDCon -- on history
       of tcp/ip (in BSD) -- abridgement of the three lectures on the
       history of BSD.

     * v
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   Retrieved from
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