Filiation of Unix and Unix-like systems

Unix (officially trademarked as UNIX®, sometimes also written as Unix or Unix® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. In Typography, small capitals (usually abbreviated small caps) are Uppercase ( capital) characters set at the same height as surrounding An operating system (commonly abbreviated OS and O/S) is the software component of a Computer system that is responsible for the management and coordination Before proposing a merge request please see Talk and see if the merger you propose has recently been made and Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) is the Research organization Kenneth Lane Thompson (born February 4 1943) commonly referred to as Ken Thompson (or simply Dennis MacAlistair Ritchie (born September 9, 1941) is an American computer scientist notable for his influence on C and other Programming Malcolm Douglas McIlroy (born 1932 is a Mathematician, Engineer, and Programmer. Today's Unix systems are split into various branches, developed over time by AT&T as well as various commercial vendors and non-profit organizations.

As of 2007, the owner of the trademark UNIX® is The Open Group, an industry standards consortium. A trademark or trade mark, represented by the symbols ™ and ®, or mark is a distinctive sign or indicator used by an individual The Open Group is an industry Consortium to set vendor- and technology-neutral open standards for Computing infrastructure Only systems fully compliant with and certified to the Single UNIX Specification qualify as "UNIX®" (others are called "Unix system-like" or "Unix-like"). The Single UNIX Specification ( SUS) is the collective name of a family of standards for Computer Operating systems to qualify for the name " Unix A Unix-like (sometimes shortened to *nix) Operating system is one that behaves in a manner similar to a Unix system while not necessarily conforming

During the late 1970s and early 1980s, the influence of Unix in academic circles led to large-scale adoption of Unix (particularly of the BSD variant, originating from the University of California, Berkeley) by commercial startups, the most notable of which is Sun Microsystems. The University of California Berkeley (also referred to as Cal, Berkeley and UC Berkeley) is a major research university located in Berkeley Sun Microsystems Inc ( is a multinational vendor of Computers computer components Computer software, and Information technology services Today, in addition to certified Unix systems, Unix-like operating systems such as GNU/Linux and BSD are commonly encountered. A Unix-like (sometimes shortened to *nix) Operating system is one that behaves in a manner similar to a Unix system while not necessarily conforming GNU ( pronounced) is a computer Operating system composed entirely of Free software. Linux (commonly pronounced ˈlɪnəks Sometimes, "traditional Unix" may be used to describe a Unix or an operating system that has the characteristics of either Version 7 Unix or UNIX System V. Seventh Edition Unix, also called Version 7 Unix, Version 7 or just V7, was an important early release of the Unix Operating system Unix System V, commonly abbreviated SysV (and usually pronounced though rarely written as System 5 was one of the versions of the Unix Operating system

Overview

Unix operating systems are widely used in both servers and workstations. A server is a Computer dedicated to providing one or more services over a computer network typically through a request-response routine A workstation, such as a Unix workstation, RISC workstation or Engineering workstation, is a high-end Microcomputer The Unix environment and the client-server program model were essential elements in the development of the Internet and the reshaping of computing as centered in networks rather than in individual computers. The client-server Software architecture model distinguishes client systems from server systems which communicate over a Computer network The Internet is a global system of interconnected Computer networks Computer networking is the Engineering Discipline concerned with communication between Computer systems or devices Networking routers

Both Unix and the C programming language were developed by AT&T and distributed to government and academic institutions, causing both to be ported to a wider variety of machine families than any other operating system. tags please moot on the talk page first! --> In Computing, C is a general-purpose cross-platform block structured As a result, Unix became synonymous with "open systems". Open systems are Computer systems that provide some combination of Interoperability, portability, and open software standards (It can also mean

Unix was designed to be portable, multi-tasking and multi-user in a time-sharing configuration. See also Software portability In Computer science, porting is the process of adapting software so that an executable program can be created In computing Multitasking is a method by which multiple tasks also known as processes, share common processing resources such as a CPU. Multi-user is a term that defines an Operating system or Application software that allows concurrent access by multiple users of a Computer. Time-sharing refers to sharing a computing resource among many users by multitasking. Unix systems are characterized by various concepts: the use of plain text for storing data; a hierarchical file system; treating devices and certain types of inter-process communication (IPC) as files; and the use of a large number of software tools, small programs that can be strung together through a command line interpreter using pipes, as opposed to using a single monolithic program that includes all of the same functionality. In Computing, plain text is a term used for an ordinary "unformatted" sequential file readable as textual material without much processing In Computing, a file system (often also written as filesystem) is a method for storing and organizing Computer files and the data they contain to make Inter-Process Communication ( IPC) is a set of techniques for the exchange of data among two or more threads in one or more processes. A programming tool or software development tool is a program or application that Software developers use to create debug maintain or otherwise In Unix-like computer Operating systems a pipeline is the original software pipeline: a set of processes chained by their Standard These concepts are known as the Unix philosophy. The Unix philosophy is a set of cultural norms and philosophical approaches to developing software based on the experience of leading developers of the Unix Operating

Under Unix, the "operating system" consists of many of these utilities along with the master control program, the kernel. In Computer science, the kernel is the central component of most computer Operating systems (OS The kernel provides services to start and stop programs, handle the file system and other common "low level" tasks that most programs share, and, perhaps most importantly, schedules access to hardware to avoid conflicts if two programs try to access the same resource or device simultaneously. In Computing, a file system (often also written as filesystem) is a method for storing and organizing Computer files and the data they contain to make To mediate such access, the kernel was given special rights on the system, leading to the division between user-space and kernel-space.

The microkernel concept was introduced in an effort to reverse the trend towards larger kernels and return to a system in which most tasks were completed by smaller utilities. A microkernel is a minimal Computer Operating system kernel which in its purest form provides no operating-system services at all only the In an era when a "normal" computer consisted of a hard disk for storage and a data terminal for input and output (I/O), the Unix file model worked quite well as most I/O was "linear". A computer terminal is an electronic or electromechanical hardware device that is used for entering data into and displaying data from a Computer or a Computing However, modern systems include networking and other new devices. As graphical user interfaces developed, the file model proved inadequate to the task of handling asynchronous events such as those generated by a mouse, and in the 1980s non-blocking I/O and the set of inter-process communication mechanisms was augmented (sockets, shared memory, message queues, semaphores), and functionalities such as network protocols were moved out of the kernel. In Computing, a mouse (plural mice, mouse devices, or mouses) Asynchronous I/O, or non-blocking I/O, is a form of Input/output processing that permits other processing to continue before the transmission has finished Inter-Process Communication ( IPC) is a set of techniques for the exchange of data among two or more threads in one or more processes. A Unix domain socket (UDS or IPC socket (inter-process communication socket is a virtual socket similar to an Internet socket that is used in POSIX In Computing, shared memory is a memory that may be simultaneously accessed by multiple programs with an intent to provide communication among them or avoid redundant copies In Computer science, a message queue is a software-engineering component used for Interprocess communication or inter- thread communication For other uses see Semaphore. A semaphore, in computer science is a protected Variable (an entity storing a value or Abstract

History

In the 1960s, the Massachusetts Institute of Technology, AT&T Bell Labs, and General Electric worked on an experimental operating system called Multics (Multiplexed Information and Computing Service), which was designed to run on the GE-645 mainframe computer. Multics ( Mult iplexed I nformation and C omputing S ervice was an extremely influential early Time-sharing Operating system The GE-600 series was a family of 36-bit mainframe Computers originating in the 1960s built by General Electric (GE Mainframes (often colloquially referred to as Big Iron) are Computers used mainly by large organizations for critical applications typically bulk data (Eventually this became a commercial product, although sales did not meet expectations. ) Multics was an interactive operating system with many novel capabilities, including enhanced security. Security is the condition of being protected against danger loss and criminals

AT&T Bell Labs pulled out of the Multics project and deployed its resources elsewhere. One of the developers on the Bell Labs team, Ken Thompson, continued to develop for the GE-645 mainframe, and wrote a game for that computer called Space Travel. Kenneth Lane Thompson (born February 4 1943) commonly referred to as Ken Thompson (or simply Space Travel was an early Computer game that simulated travel in the Solar system. ^[1] However, he found that the game was too slow on the GE machine and was expensive, costing $75 per execution in scarce computing time. ^[2]

Thompson thus re-wrote the game in assembly language for Digital Equipment Corporation's PDP-7 with help from Dennis Ritchie. See the terminology section below for information regarding inconsistent use of the terms assembly and assembler Digital Equipment Corporation was a pioneering American company in the Computer industry The DEC PDP-7 is a Minicomputer produced by Digital Equipment Corporation. Dennis MacAlistair Ritchie (born September 9, 1941) is an American computer scientist notable for his influence on C and other Programming This experience, combined with his work on the Multics project, led Thompson to start a new operating system for the PDP-7. Thompson and Ritchie led a team of developers, including Rudd Canaday, at Bell Labs developing a file system as well as the new multi-tasking operating system itself. They included a command line interpreter and some small utility programs. ^[3]

1970s

In the 1970s the project was named Unics, and eventually could support two simultaneous users. Brian Kernighan invented this name as a contrast to Multics; the spelling was later changed to Unix. Brian Wilson Kernighan (ˈkɛrnɪhæn the 'g' is silent (born 1942 Toronto, Ontario, Canada) is a Computer scientist who worked at

Up until this point there had been no financial support from Bell Labs. When the Computer Science Research Group wanted to use Unix on a much larger machine than the PDP-7, Thompson and Ritchie managed to trade the promise of adding text processing capabilities to Unix for a PDP-11/20 machine. The PDP-11 was a series of 16-bit Minicomputers sold by Digital Equipment Corp This led to some financial support from Bell. For the first time in 1970, the Unix operating system was officially named and ran on the PDP-11/20. It added a text formatting program called roff and a text editor. roff was the first Unix Text-formatting Computer program, also the most important application run on the first machine specifically purchased to run A text editor is a type of program used for editing plain Text files Text editors are often provided with Operating systems or software development All three were written in PDP-11/20 assembly language. Bell Labs used this initial "text processing system", made up of Unix, roff, and the editor, for text processing of patent applications. A patent is a set of Exclusive rights granted by a State to an inventor or his assignee for a fixed period of time in exchange for a disclosure of an Roff soon evolved into troff, the first electronic publishing program with a full typesetting capability. See also Trough. TROFF may also refer to a command in the BASIC programming language. Typesetting involves the presentation of textual material in graphic form on Paper or some other medium. The UNIX Programmer's Manual was published on November 3, 1971. Events 644 - Umar ibn al-Khattab, the second Muslim Caliph, is killed by a Persian slave in Medina. Year 1971 ( MCMLXXI) was a Common year starting on Friday (link will display full calendar of the 1971 Gregorian calendar.

In 1973, Unix was rewritten in the C programming language, contrary to the general notion at the time "that something as complex as an operating system, which must deal with time-critical events, had to be written exclusively in assembly language". tags please moot on the talk page first! --> In Computing, C is a general-purpose cross-platform block structured ^[4] The migration from assembly language to the higher-level language C resulted in much more portable software, requiring only a relatively small amount of machine-dependent code to be replaced when porting Unix to other computing platforms. See the terminology section below for information regarding inconsistent use of the terms assembly and assembler In computing a high-level programming language is a Programming language with strong abstraction from the details of the computer In the context of Software engineering, software quality measures how well Software is designed ( quality of design) and how well the software conforms In Computing, a platform describes some sort of Hardware architecture or Software framework (including Application frameworks, that allows

AT&T made Unix available to universities and commercial firms, as well as the United States government under licenses. The federal government of the United States is the central United States Governmental body established by the United States Constitution. The licenses included all source code including the machine-dependent parts of the kernel, which were written in PDP-11 assembly code. Copies of the annotated Unix kernel sources circulated widely in the late 1970s in the form of a much-copied book by John Lions of the University of New South Wales, the Lions' Commentary on UNIX 6th Edition, with Source Code, which led to considerable use of Unix as an educational example. John Lions ( January 19 1937 in Sydney, Australia &ndash December 5, 1998 in Sydney) was an Australian The University of New South Wales, also known as UNSW or colloquially as New South, is a University situated in Kensington, a suburb in Lions' Commentary on UNIX 6th Edition with Source Code by John Lions ( 1976) contains the complete Source code of the 6th Edition

Versions of the Unix system were determined by editions of its user manuals, so that (for example) "Fifth Edition UNIX" and "UNIX Version 5" have both been used to designate the same thing. Development expanded, with Versions 4, 5, and 6 being released by 1975. Sixth Edition Unix, also called Version 6 Unix or just V6, was the first version of the Unix Operating system to see wide release outside These versions added the concept of pipes, leading to the development of a more modular code-base, increasing development speed still further. Version 5 and especially Version 6 led to a plethora of different Unix versions both inside and outside Bell Labs, including PWB/UNIX, IS/1 (the first commercial Unix), and the University of Wollongong's port to the Interdata 7/32 (the first non-PDP Unix). PWB/UNIX (for Programmer's Workbench) was an early version of the Unix Operating system. INTERACTIVE Systems Corporation ( ISC) was a Software company, known for their versions of the Unix Operating system. The University of Wollongong (UOW is a public university with approximately 22000 students located in the coastal city of Wollongong, which is 80 kilometres south of The Model 7/32 and Model 8/32 were 32-bit Minicomputers developed by Interdata Inc

In 1978, UNIX/32V, for DEC's then new VAX system, was released. UNIX/32V was an early version of the Unix Operating system from Bell Laboratories, released in June 1979. Digital Equipment Corporation was a pioneering American company in the Computer industry Name "VAX" was originally an Acronym for V irtual A ddress e' X' tension, both because the VAX was seen as a 32-bit 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. Seventh Edition Unix, also called Version 7 Unix, Version 7 or just V7, was an important early release of the Unix Operating system Research Unix is a term used to refer to versions of the Unix Operating system for DEC PDP-7, PDP-11, VAX and Interdata 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. Eight Edition Unix, also known as Version 8 Unix or V8, was a version of the Research Unix Operating system developed and used internally at Ninth Edition Unix, also known as Version 9 Unix or V9, was a version of the Research Unix Operating system developed and used internally at Tenth Edition Unix, also known as Version 10 Unix or V10, was the last version of the Research Unix Operating system developed and used internally This research led to the development of Plan 9 from Bell Labs, a new portable distributed system. Plan 9 from Bell Labs is a Distributed operating system, primarily used for research

1980s

A late-80s style Unix desktop running the X Window System graphical user interface. Shown are a number of client applications common to the MIT X Consortium's distribution, including Tom's Window Manager, an X Terminal, Xbiff, xload, and a graphical manual page browser. In Computing, twm ( Timeless Windows Manager) is the standard window manager for the X Window System, version X11R4 onwards In Computing, xterm is the standard Terminal emulator for the X Window System. xbiff is a small utility for the X Window System that shows a mailbox with its flag raised whenever the user has new E-mail. Almost all substantial UNIX and Unix-like Operating systems have extensive documentation known as man pages (short for "manual pages"

AT&T licensed UNIX System III, based largely on Version 7, for commercial use, the first version launching in 1982. UNIX System III (sometimes called System 3) was a version of the Unix operating system released by AT&T 's Unix Support Group (USG 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. Unix System V, commonly abbreviated SysV (and usually pronounced though rarely written as System 5 was one of the versions of the Unix Operating system 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. vi is a screen-oriented Text editor written by Bill Joy in 1976 for an early BSD release curses is a terminal control library for Unix-like systems enabling the construction of text user interface (TUI applications The University of California Berkeley (also referred to as Cal, Berkeley and UC Berkeley) is a major research university located in Berkeley This also included support for the Western Electric 3B series of machines. Western Electric Company (sometimes abbreviated WE and WECo) was an American Electrical engineering company the manufacturing arm

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 Unix as an alternative to UNIX System III and V, originally on the PDP-11 architecture (the 2. xBSD releases, ending with 2. 11BSD) and later for the VAX-11 (the 4. x BSD releases). Many contributions to Unix first appeared on BSD releases, notably the C shell with job control (modelled on ITS). The C shell ( csh) is a Unix shell developed by Bill Joy for the BSD Unix system On Operating systems that support executing multiple processes in parallel or in series ( Batch processing) job control refers to the orchestration of multiple ITS, the Incompatible Timesharing System (named in comparison with the Compatible Time-Sharing System also in use at MIT was an early revolutionary and influential Perhaps the most important aspect of the BSD development effort was the addition of TCP/IP network code to the mainstream Unix kernel. The Internet Protocol Suite (commonly TCP/IP) is the set of Communications protocols used for the Internet and other similar networks A computer network is a group of interconnected Computers. Networks may be classified according to a wide variety of characteristics In Computer science, the kernel is the central component of most computer Operating systems (OS 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. Computer Consoles Inc or CCI was a Telephony and Computer company located in Rochester New York, USA, which did business first 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. Microsoft Windows is a series of Software Operating systems and Graphical user interfaces produced by Microsoft. The accompanying Berkeley Sockets API is a de facto standard for networking APIs and has been copied on many platforms. The Berkeley sockets Application programming interface (API comprises a library for developing applications in the C programming language that perform

Other companies began to offer commercial versions of the UNIX System for their own mini-computers and workstations. Most of these new Unix flavors were developed from the System V base under a license from AT&T; however, others were based on BSD instead. One of the leading developers of BSD, Bill Joy, went on to co-found Sun Microsystems in 1982 and created SunOS (now Solaris) for their workstation computers. William Nelson Joy (born Nov 8, 1954) commonly known as Bill Joy, is an American Computer scientist. Sun Microsystems Inc ( is a multinational vendor of Computers computer components Computer software, and Information technology services SunOS is a version of the Unix Operating system developed by Sun Microsystems for their Workstation and server Computer Solaris is a Unix -based Operating system introduced by Sun Microsystems in 1992 as the successor to SunOS. A workstation, such as a Unix workstation, RISC workstation or Engineering workstation, is a high-end Microcomputer In 1980, Microsoft announced its first Unix for 16-bit microcomputers called Xenix, which the Santa Cruz Operation (SCO) ported to the Intel 8086 processor in 1983, and eventually branched Xenix into SCO UNIX in 1989. Microsoft Corporation is an American multinational Computer technology Corporation, which rose to dominate the Home computer Xenix is a version of the Unix Operating system, licensed by Microsoft from AT&T in the late 1970s Santa Cruz Operation ( SCO) was a Software company based in Santa Cruz California which was best known for selling three Unix variants for The 8086 is a 16-bit Microprocessor chip designed by Intel and introduced on the market in 1978 which gave rise to the X86 architecture SCO OpenServer, previously SCO UNIX and SCO Open Desktop ( SCO ODT) is a closed source version of the Unix computer Operating system

For a few years during this period (before PC compatible computers with MS-DOS became dominant), industry observers expected that UNIX, with its portability and rich capabilities, was likely to become the industry standard operating system for microcomputers. IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. MS-DOS (short for M icro' s' oft D isk O perating S ystem is an Operating system commercialized by Microsoft. ^[5] In 1984 several companies established the X/Open consortium with the goal of creating an open system specification based on UNIX. X/Open Company Ltd was a Consortium founded by several European UNIX systems manufacturers in 1984 to identify and promote Open standards in the field Despite early progress, the standardization effort collapsed into the "Unix wars," with various companies forming rival standardization groups. The Unix wars were the struggles between Vendors of the Unix Computer Operating system in the late 1980s and early 1990s to set the standard for The most successful Unix-related standard turned out to be the IEEE's POSIX specification, designed as a compromise API readily implemented on both BSD and System V platforms, published in 1988 and soon mandated by the United States government for many of its own systems. The Institute of Electrical and Electronics Engineers or IEEE (read eye-triple-e) is an international Non-profit, professional organization POSIX (ˈpɒzɪks or "Portable Operating System Interface" is the collective name of a family of related standards specified by the IEEE to define Year 1988 ( MCMLXXXVIII) was a Leap year starting on Friday (link displays 1988 Gregorian calendar) The federal government of the United States is the central United States Governmental body established by the United States Constitution.

AT&T added various features into UNIX System V, such as file locking, system administration, streams, new forms of IPC, the Remote File System and TLI. File locking is a mechanism that enforces access to a Computer file by only one user or process at any specific time A system administrator, systems administrator, or sysadmin, is a person employed to maintain and operate a Computer system and/or network. In Unix and Unix-like operating systems as well as certain Programming language interfaces the standard streams are preconnected input and output channels The Remote File System ( RFS) was a Distributed file system developed by AT&T in the 1980s In Computer networking, the Transport Layer Interface (TLI was the networking API provided by AT&T UNIX System V Release 3 (SVR3 and Release AT&T cooperated with Sun Microsystems and between 1987 and 1989 merged features from Xenix, BSD, SunOS, and System V into System V Release 4 (SVR4), independently of X/Open. Xenix is a version of the Unix Operating system, licensed by Microsoft from AT&T in the late 1970s Unix System V, commonly abbreviated SysV (and usually pronounced though rarely written as System 5 was one of the versions of the Unix Operating system This new release consolidated all the previous features into one package, and heralded the end of competing versions. It also increased licensing fees.

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. Addamax was founded in 1986 in Champaign Illinois by Dr Peter A Trusted Operating System (TOS generally refers to an Operating system that provides sufficient support for Multilevel security and evidence of correctness to

1990s

In 1990, the Open Software Foundation released OSF/1, their standard Unix implementation, based on Mach and BSD. The Open Software Foundation ( OSF) was an organization founded in 1988 to create an Open standard for an implementation of the Unix operating Mach is an Operating system Microkernel developed at Carnegie Mellon University to support operating system research primarily distributed and parallel The Foundation was started in 1988 and was funded by several Unix-related companies that wished to counteract the collaboration of AT&T and Sun on SVR4. Subsequently, AT&T and another group of licensees formed the group "UNIX International" in order to counteract OSF. Unix International or UI was an association created in 1988 to promote open standards especially the Unix Operating system. This escalation of conflict between competing vendors gave rise again to the phrase "Unix wars". The Unix wars were the struggles between Vendors of the Unix Computer Operating system in the late 1980s and early 1990s to set the standard for

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). Berkeley Software Design Inc (BSDI or later BSDi was a corporation which developed sold licences to and supported BSD/OS (previously known as BSD/386 a commercial and BSDI produced a fully functional commercial version of BSD Unix for the inexpensive and ubiquitous Intel platform, which started a wave of interest in the use of inexpensive hardware for production computing. Shortly after it was founded, Bill Jolitz left BSDI to pursue distribution of 386BSD, the free software ancestor of FreeBSD, OpenBSD, and NetBSD. 386BSD, sometimes called " JOLIX " is a free BSD Unix Operating system for PC compatible computer systems based FreeBSD is a Unix-like free Operating system descended from AT&T UNIX via the Berkeley Software Distribution (BSD branch through OpenBSD is a Unix-like computer Operating system descended from Berkeley Software Distribution (BSD a Unix derivative developed at the NetBSD is a freely redistributable Open source version of the Unix -derivative Berkeley Software Distribution (BSD Computer Operating

By 1993 most commercial vendors had changed their variants of Unix to be based on System V with many BSD features added on top. Unix System V, commonly abbreviated SysV (and usually pronounced though rarely written as System 5 was one of the versions of the Unix Operating system The creation of the 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 Common Open Software Environment or COSE was an initiative formed in March 1993 by the major Unix vendors of the time to create open unified Operating The new combined entity, which retained the OSF name, stopped work on OSF/1 that year. By that time the only vendor using it was Digital, which continued its own development, rebranding their product Digital UNIX in early 1995. Digital Equipment Corporation was a pioneering American company in the Computer industry Tru64 UNIX is a 64-bit UNIX Operating system for the Alpha Microprocessor architecture currently owned by Hewlett-Packard

Shortly after UNIX System V Release 4 was produced, AT&T sold all its rights to UNIX to Novell. Novell Inc ( is a global Software Corporation based in the United States specializing in enterprise operating systems such as SUSE (Dennis Ritchie likened this to the Biblical story of Esau selling his birthright for the proverbial "mess of pottage". Esau (ˈisɔ ( Hebrew, Standard Hebrew Esav, Tiberian Hebrew ʿĒśāw) is the brother of Jacob (whom God renamed The phrase mess of pottage means something of little value It is associated with the exchange by Esau of his birthright for a meal of Lentil stew as described in ^[6]) Novell developed its own version, UnixWare, merging its NetWare with UNIX System V Release 4. UnixWare is a Unix Operating system maintained by The SCO Group (SCO NetWare is a Network operating system developed by Novell Inc Novell tried to use this to battle against Windows NT, but their core markets suffered considerably. Windows NT is a family of Operating systems produced by Microsoft, the first version of which was released in July 1993

In 1993, Novell decided to transfer the UNIX® trademark and certification rights to the X/Open Consortium. A trademark or trade mark, represented by the symbols ™ and ®, or mark is a distinctive sign or indicator used by an individual X/Open Company Ltd was a Consortium founded by several European UNIX systems manufacturers in 1984 to identify and promote Open standards in the field ^[7] In 1996, X/Open merged with OSF, creating the Open Group. The Open Software Foundation ( OSF) was an organization founded in 1988 to create an Open standard for an implementation of the Unix operating The Open Group is an industry Consortium to set vendor- and technology-neutral open standards for Computing infrastructure 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. The Single UNIX Specification ( SUS) is the collective name of a family of standards for Computer Operating systems to qualify for the name " Unix

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. ^[8] Whether Novell also sold the copyrights is currently the subject of litigation (see below).

In 1997, Apple Computer sought out a new foundation for its Macintosh operating system and chose NEXTSTEP, an operating system developed by NeXT. Apple Inc, ( formerly Apple Computer Inc, is an American Multinational corporation with a focus on designing and manufacturing Consumer electronics Nextstep was the original object-oriented, multitasking Operating system that NeXT Computer developed to run on its range of proprietary computers NeXT Computer Inc (later NeXT Software Inc) was an American Computer company headquartered in Redwood City, California that The core operating system, which was based on BSD and the Mach kernel, was renamed Darwin after Apple acquired it. Mach is an Operating system Microkernel developed at Carnegie Mellon University to support operating system research primarily distributed and parallel Darwin is an open source UNIX -based computer Operating system released by Apple Inc 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. Mac OS X (mæk oʊ ɛs tɛn is a line of computer Operating systems developed marketed and sold by Apple Inc, the latest of which is pre-loaded on all currently The USENIX Association is the Advanced Computing Technical Association A desktop computer is a Personal computer (PC in a form intended for regular use at a single location as opposed to a mobile Laptop or portable computer

2000 to present

See also: SCO-Linux controversies

A modern Unix desktop environment (Solaris 10)

In 2000, SCO sold its entire UNIX business and assets to Caldera Systems, which later on changed its name to The SCO Group. The SCO-Linux controversies are a series of legal and public disputes between the Software company SCO Group (SCO and various Linux vendors and users Solaris is a Unix -based Operating system introduced by Sun Microsystems in 1992 as the successor to SunOS. Santa Cruz Operation ( SCO) was a Software company based in Santa Cruz California which was best known for selling three Unix variants for The SCO Group Inc ( TSG, informally SCO;) is a software company formerly called Caldera Systems and Caldera International. This new player then 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. International Business Machines Corporation abbreviated IBM and nicknamed "Big Blue", is a multinational Computer Technology 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. SCO v Novell is a lawsuit brought by the SCO Group against Novell. On August 10, 2007, a major portion of the case (the fact that Novell had the copyright to UNIX, and that the SCO Group had improperly kept money that was due to Novell) was decided in Novell's favor. Events 612 BC - Killing of Sinsharishkun, King of Assyrian Empire Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. 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". ^[9][10][11]

Unix has been losing market share, particularly to Linux. The Dot-com crash has led to significant consolidation of versions of Unix. The " dot-com bubble " (or sometimes the " IT bubble " was a speculative bubble covering roughly 1995–2001 (with a climax on March 10 Of the many commercial flavors of Unix that were born in the 1980s, only Solaris, HP-UX, and AIX are still doing relatively well in the market, though SGI's IRIX persisted for quite some time. Solaris is a Unix -based Operating system introduced by Sun Microsystems in 1992 as the successor to SunOS. HP-UX (Hewlett Packard UniX is Hewlett-Packard 's proprietary implementation of the Unix Operating system, based on System V (initially IRIX is a computer Operating system developed by Silicon Graphics Inc Of these, Solaris has the largest market share. ^[12]

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. Sun Microsystems Inc ( is a multinational vendor of Computers computer components Computer software, and Information technology services Unix System V, commonly abbreviated SysV (and usually pronounced though rarely written as System 5 was one of the versions of the Unix Operating system Open source is a development methodology which offers practical accessibility to a product's source (goods and knowledge OpenSolaris is an Open source project created by Sun Microsystems to build a developer community around Solaris Operating System technology New Sun OS technologies such as the ZFS file system are now first released as open source code via the OpenSolaris project; as of 2006 it has spawned several non-Sun distributions such as SchilliX, Belenix, Nexenta and MarTux. In Computing, ZFS is a File system designed by Sun Microsystems for the Solaris Operating System. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. SchilliX is a Live CD Operating system distribution based on OpenSolaris. BeleniX is an operating system distribution built using the OpenSolaris source base Nexenta OS is a computer Operating system based on Debian / Ubuntu and Solaris for IA-32 and X86-64 based systems

Standards

Beginning in the late 1980s, an open operating system standardization effort now known as POSIX provided a common baseline for all operating systems; IEEE based POSIX around the common structure of the major competing variants of the Unix system, publishing the first POSIX standard in 1988. POSIX (ˈpɒzɪks or "Portable Operating System Interface" is the collective name of a family of related standards specified by the IEEE to define The Institute of Electrical and Electronics Engineers or IEEE (read eye-triple-e) is an international Non-profit, professional organization In the early 1990s a separate but very similar effort was started by an industry consortium, the Common Open Software Environment (COSE) initiative, which eventually became the Single UNIX Specification administered by The Open Group). The Common Open Software Environment or COSE was an initiative formed in March 1993 by the major Unix vendors of the time to create open unified Operating The Single UNIX Specification ( SUS) is the collective name of a family of standards for Computer Operating systems to qualify for the name " Unix The Open Group is an industry Consortium to set vendor- and technology-neutral open standards for Computing infrastructure Starting in 1998 the Open Group and IEEE started the Austin Group, to provide a common definition of POSIX and the Single UNIX Specification. The Austin Group or the Austin Common Standards Revision Group is a joint technical Working group formed to develop and maintain a common revision of POSIX

In an effort towards compatibility, in 1999 several Unix system vendors agreed on SVR4's Executable and Linkable Format (ELF) as the standard for binary and object code files. In Computing, the Executable and Linking Format ( ELF, formerly called Extensible Linking Format) is a common standard File format for Executables The common format allows substantial binary compatibility among Unix systems operating on the same CPU architecture.

The Filesystem Hierarchy Standard was created to provide a reference directory layout for Unix-like operating systems, particularly Linux. The Filesystem Hierarchy Standard (FHS defines the main directories and their contents in most Linux -based computer Operating systems It is a formalization and extension

Components

See also: List of Unix programs

The Unix system is composed of several components that are normally packaged together. This is a list of UNIX utilities as specified by IEEE Std 1003 By including — in addition to the kernel of an operating system — the development environment, libraries, documents, and the portable, modifiable source-code for all of these components, Unix was a self-contained software system. In Computer science, the kernel is the central component of most computer Operating systems (OS This was one of the key reasons it emerged as an important teaching and learning tool and has had such a broad influence.

The inclusion of these components did not make the system large — the original V7 UNIX distribution, consisting of copies of all of the compiled binaries plus all of the source code and documentation occupied less than 10MB, and arrived on a single 9-track magnetic tape. Magnetic tape has been used for Data storage for over 50 years The printed documentation, typeset from the on-line sources, was contained in two volumes.

The names and filesystem locations of the Unix components has changed substantially across the history of the system. Nonetheless, the V7 implementation is considered by many to have the canonical early structure:

• Kernel — source code in /usr/sys, composed of several sub-components:
  • conf — configuration and machine-dependent parts, including boot code
  • dev — device drivers for control of hardware (and some pseudo-hardware)
  • sys — operating system "kernel", handling memory management, process scheduling, system calls, etc.
  • h — header files, defining key structures within the system and important system-specific invariables
• Development Environment — Early versions of Unix contained a development environment sufficient to recreate the entire system from source code:
  • cc — C language compiler (first appeared in V3 Unix)
  • as — machine-language assembler for the machine
  • ld — linker, for combining object files
  • lib — object-code libraries (installed in /lib or /usr/lib) libc, the system library with C run-time support, was the primary library, but there have always been additional libraries for such things as mathematical functions (libm) or database access. V7 Unix introduced the first version of the modern "Standard I/O" library stdio as part of the system library. Later implementations increased the number of libraries significantly.
  • make - build manager (introduced in PWB/UNIX), for effectively automating the build process
  • include — header files for software development, defining standard interfaces and system invariants
  • Other languages — V7 Unix contained a Fortran-77 compiler, a programmable arbitrary-precision calculator (bc, dc), and the awk "scripting" language, and later versions and implementations contain many other language compilers and toolsets. In Software development, make is a utility for automatically building executable programs from Source code. PWB/UNIX (for Programmer's Workbench) was an early version of the Unix Operating system. AWK is a general purpose Programming language that is designed for processing text-based data either in files or data streams and was created at Bell Labs in the 1970s Early BSD releases included Pascal tools, and many modern Unix systems also include the GNU Compiler Collection as well as or instead of a proprietary compiler system. Pascal is an influential imperative and procedural Programming language, designed in 1968/9 and published in 1970 by Niklaus Wirth as a small The GNU Compiler Collection (usually shortened to GCC) is a set of Compilers produced for various Programming languages by the GNU Project
  • Other tools — including an object-code archive manager (ar), symbol-table lister (nm), compiler-development tools (e. g. lex & yacc), and debugging tools.
• Commands — Unix makes little distinction between commands (user-level programs) for system operation and maintenance (e. g. cron), commands of general utility (e. g. grep), and more general-purpose applications such as the text formatting and typesetting package. Nonetheless, some major categories are:
  • sh — The "shell" programmable command line interpreter, the primary user interface on Unix before window systems appeared, and even afterward (within a "command window"). The Bourne shell, or sh, was the default Unix shell of Unix Version 7, and replaced the Thompson shell, whose executable file had the same
  • Utilities — the core tool kit of the Unix command set, including cp, ls, grep, find and many others. Subcategories include:
    • System utilities — administrative tools such as mkfs, fsck, and many others
    • User utilities — environment management tools such as passwd, kill, and others.
  • Document formatting — Unix systems were used from the outset for document preparation and typesetting systems, and included many related programs such as nroff, troff, tbl, eqn, refer, and pic. nroff (short for "new Roff " is a Unix Text-formatting program; it produces output suitable for simple fixed-width printers See also Trough. TROFF may also refer to a command in the BASIC programming language. Part of the Troff suite of Unix document layout tools tbl is a preprocessor that formats tables. Part of the Troff suite of Unix document layout tools eqn is a Preprocessor that formats equations for printing refer is a program for managing bibliographic referencesand citing them in Troff documents Pic is a Domain-specific language by Brian Kernighan for specifying Diagrams in terms of objects such as boxes with arrows between them Some modern Unix systems also include packages such as TeX and Ghostscript. TeX (ˈtɛx as in Greek, often /ˈtɛk/ in English; written with a lowercase 'e' in imitation of the logo is a Typesetting system designed and mostly Ghostscript is a suite of Software based on an interpreter for Adobe Systems ' PostScript and Portable Document Format (PDF Page description
  • Graphics — The plot subsystem provided facilities for producing simple vector plots in a device-independent format, with device-specific interpreters to display such files. Modern Unix systems also generally include X11 as a standard windowing system and GUI, and many support OpenGL. OpenGL ( Open G raphics L ibrary is a standard specification defining a cross-language Cross-platform API for writing applications that produce
  • Communications — Early Unix systems contained no inter-system communication, but did include the inter-user communication programs mail and write. V7 introduced the early inter-system communication system UUCP, and systems beginning with BSD release 4. UUCP is an Abbreviation for Unix to Unix CoPy. The term generally refers to a suite of Computer programs and protocols allowing remote execution 1c included TCP/IP utilities. The Internet Protocol Suite (commonly TCP/IP) is the set of Communications protocols used for the Internet and other similar networks

The 'man' command can display a 'man page' for every command on the system, including itself.

• Documentation — Unix was the first operating system to include all of its documentation online in machine-readable form. The documentation included:
  • man — manual pages for each command, library component, system call, header file, etc. Almost all substantial UNIX and Unix-like Operating systems have extensive documentation known as man pages (short for "manual pages" In Computing, a system call is the mechanism used by an application program to request service from the Kernel.
  • doc — longer documents detailing major subsystems, such as the C language and troff

Unix impact

The Unix system had significant impact on other operating systems.

It was written in high level language as opposed to assembly language (which had been thought necessary for systems implementation on early computers). See the terminology section below for information regarding inconsistent use of the terms assembly and assembler Although this followed the lead of Multics and Burroughs, it was Unix that popularized the idea. Multics ( Mult iplexed I nformation and C omputing S ervice was an extremely influential early Time-sharing Operating system The Burroughs large systems were the largest of three series of Burroughs Corporation mainframe computers

Unix had a drastically simplified file model compared to many contemporary operating systems, treating all kinds of files as simple byte arrays. The file system hierarchy contained machine services and devices (such as printers, terminals, or disk drives), providing a uniform interface, but at the expense of occasionally requiring additional mechanisms such as ioctl and mode flags to access features of the hardware that did not fit the simple "stream of bytes" model. A computer terminal is an electronic or electromechanical hardware device that is used for entering data into and displaying data from a Computer or a Computing Disk storage is a general category of a Computer storage mechanisms in which data is recorded on planar round and rotating surfaces ( disks, discs, or In computing an ioctl (aɪˈɒktəl or "i-o-control" is part of the user -to- kernel interface of a conventional operating system The Plan 9 operating system pushed this model even further and eliminated the need for additional mechanisms. Plan 9 from Bell Labs is a Distributed operating system, primarily used for research

Linux has been adapted to boot from flash memory cards.

Unix also popularized the hierarchical file system with arbitrarily nested subdirectories, originally introduced by Multics. Other common operating systems of the era had ways to divide a storage device into multiple directories or sections, but they had a fixed number of levels, often only one level. Several major proprietary operating systems eventually added recursive subdirectory capabilities also patterned after Multics. DEC's RSX-11M's "group, user" hierarchy evolved into VMS directories, CP/M's volumes evolved into MS-DOS 2. RSX-11 is a family of Real-time operating systems mainly for PDP-11 computers created by Digital Equipment Corporation (DEC common in the late 1970s Open Virtual Memory System ( OpenVMS) initially known just as Virtual Memory System ( VMS) is the name of a High-end Computer server CP/M (Control Program for Microcomputers is an Operating system originally created for Intel 8080 / 85 based Microcomputers by Gary Kildall MS-DOS (short for M icro' s' oft D isk O perating S ystem is an Operating system commercialized by Microsoft. 0+ subdirectories, and HP's MPE group. MPE ( Multi-Programming Executive) is an early 1980s era business-oriented Minicomputer Operating system made by Hewlett-Packard. account hierarchy and IBM's SSP and OS/400 library systems were folded into broader POSIX file systems. System Support Program ( SSP) was an Operating system for the IBM System/34 and System/36 Minicomputers SSP was a command-based IBM i is an Operating system used on IBM Power Systems, a unified server platform from the former IBM System i and IBM System p servers

Making the command interpreter an ordinary user-level program, with additional commands provided as separate programs, was another Multics innovation popularized by Unix. The Unix shell used the same language for interactive commands as for scripting (shell scripts — there was no separate job control language like IBM's JCL). A Unix shell, is a command line shell that provides the traditional User interface for the Unix Operating system and for Unix-like A shell script is a script written for the shell, or Command line interpreter, of an Operating system. Job Control Language ( JCL) is a Scripting language used on IBM mainframe operating systems to instruct the system on how to run a batch job or Since the shell and OS commands were "just another program", the user could choose (or even write) his own shell. New commands could be added without changing the shell itself. Unix's innovative command-line syntax for creating chains of producer-consumer processes (pipelines) made a powerful programming paradigm (coroutines) widely available. In Unix-like computer Operating systems a pipeline is the original software pipeline: a set of processes chained by their Standard In Computer science, coroutines are program components that generalize Subroutines to allow multiple entry points and suspending and resuming of execution at certain Many later command-line interpreters have been inspired by the Unix shell.

A fundamental simplifying assumption of Unix was its focus on ASCII text for nearly all file formats. There were no "binary" editors in the original version of Unix — the entire system was configured using textual shell command scripts. The common denominator in the I/O system was the byte — unlike "record-based" file systems. In Computer science, a record-oriented filesystem is a File system where files are stored as a collection The focus on text for representing nearly everything made Unix pipes especially useful, and encouraged the development of simple, general tools that could be easily combined to perform more complicated ad hoc tasks. The focus on text and bytes made the system far more scalable and portable than other systems. Over time, text-based applications have also proven popular in application areas, such as printing languages (PostScript), and at the application layer of the Internet Protocols, e. PostScript ( PS) is a dynamically typed concatenative Programming language created by John Warnock and Charles Geschke in 1982 The Internet Protocol ( IP) is a protocol used for communicating data across a Packet-switched Internetwork using the Internet Protocol g. Telnet, FTP, SSH, SMTP, HTTP and SIP.

Unix popularized a syntax for regular expressions that found widespread use. In Computing, regular expressions provide a concise and flexible means for identifying strings of text of interest such as particular characters words or patterns of characters The Unix programming interface became the basis for a widely implemented operating system interface standard (POSIX, see above).

The C programming language soon spread beyond Unix, and is now ubiquitous in systems and applications programming. tags please moot on the talk page first! --> In Computing, C is a general-purpose cross-platform block structured

Early Unix developers were important in bringing the theory of modularity and reusability into software engineering practice, spawning a "Software Tools" movement. Modular programming is a software design technique that increases the extent to which software is composed from separate parts called modules In Computer science and Software engineering, reusability is the likelihood a segment of source code can be used again to add new functionalities with slight or no Software engineering is the application of a systematic disciplined quantifiable approach to the development operation and maintenance of Software.

Unix provided the TCP/IP networking protocol on relatively inexpensive computers, which contributed to the Internet explosion of world-wide real-time connectivity, and which formed the basis for implementations on many other platforms. The Internet is a global system of interconnected Computer networks (This also exposed numerous security holes in the networking implementations. )

The Unix policy of extensive on-line documentation and (for many years) ready access to all system source code raised programmer expectations, and contributed to the 1983 launch of the free software movement. The free software movement (also known as open source movement, free and open source software movement and abbreviated FSM OSM or FOSSM) is a relatively

Over time, the leading developers of Unix (and programs that ran on it) evolved a set of cultural norms for developing software, norms which became as important and influential as the technology of Unix itself; this has been termed the Unix philosophy. The Unix philosophy is a set of cultural norms and philosophical approaches to developing software based on the experience of leading developers of the Unix Operating

2038

Main article: Year 2038 problem

Unix stores system time values as the number of seconds from midnight January 1, 1970 (the "Unix Epoch") in variables of type time_t, historically defined as "signed 32-bit integer". The year 2038 problem (also known as "Unix Millennium bug" or "Y2K38" by analogy to the Y2K problem) may cause some Computer software to fail In Computer science and Computer programming, system time represents a computer system's notion of the passing of Time. New Year See also New Year The Ancient Romans began their consular year on January 1st since 153 BC Year 1970 ( MCMLXX) was a Common year starting on Thursday (link shows full calendar of the Gregorian calendar. Unix time, or POSIX time, is a system for describing points in Time, defined as the number of seconds elapsed since Midnight Coordinated Universal The time_t datatype is a Data type in the ISO C library defined for storing System time values On January 19, 2038, the current time will roll over from a zero followed by 31 ones (01111111111111111111111111111111) to a one followed by 31 zeros (10000000000000000000000000000000), which will reset time to the year 1901 or 1970, depending on implementation, because that toggles the sign bit. Events 1419 - Hundred Years' War: Rouen surrenders to Henry V of England completing his reconquest of Normandy. 2038 ( MMXXXVIII) will be a Common year starting on Friday of the Gregorian calendar. In Computer science, the sign bit is a Bit (usually the Most significant bit) in a Computer numbering format that indicates the sign As many applications use OS library routines for date calculations, the impact of this could be felt much earlier than 2038; for instance, 30-year mortages may be calculated incorrectly beginning in the year 2008. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common

Since times before 1970 are rarely represented in Unix time, one possible solution that is compatible with existing binary formats would be to redefine time_t as "unsigned 32-bit integer". Unix time, or POSIX time, is a system for describing points in Time, defined as the number of seconds elapsed since Midnight Coordinated Universal However, such a kludge merely postpones the problem to February 7, 2106, and could introduce bugs in software that compares differences between two sets of time. A kludge (alternately kluge) is a clumsy or inelegant solution to a problem or difficulty Events 457 - Leo I becomes emperor of the Byzantine Empire. 1074 - Battle of Montesarchio in which the Prince

Some Unix versions have already addressed this. For example, in Solaris on 64-bit systems, time_t is 64 bits long, meaning that the OS itself and 64-bit applications will correctly handle dates for some 292 billion years. Existing 32-bit applications using a 32-bit time_t continue to work on 64-bit Solaris systems but are still prone to the 2038 problem.

Free Unix-like operating systems

Linux is a modern Unix-like system (Ubuntu Hardy Heron pictured)

In 1983, Richard Stallman announced the GNU project, an ambitious effort to create a free software Unix-like system; "free" in that everyone who received a copy would be free to use, study, modify, and redistribute it. Richard Matthew Stallman (born March 16 1953 often abbreviated " rms " is an American software freedom activist GNU ( pronounced) is a computer Operating system composed entirely of Free software. Free software or software libre is Software that can be used studied and modified without restriction and which can be copied and redistributed in modified or unmodified A Unix-like (sometimes shortened to *nix) Operating system is one that behaves in a manner similar to a Unix system while not necessarily conforming The GNU project's own kernel development project, GNU Hurd, had not produced a working kernel, but the Linux kernel was released as free software in 1992 under the GNU General Public License. Linux is an operating system kernel used by a family of Unix-like Operating systems These are popularly termed Linux operating systems and In addition to their use in the Linux operating system, many GNU packages — such as the GNU Compiler Collection (and the rest of the GNU toolchain), the GNU C library and the GNU core utilities — have gone on to play central roles in other free Unix systems as well. Linux (commonly pronounced ˈlɪnəks The GNU Compiler Collection (usually shortened to GCC) is a set of Compilers produced for various Programming languages by the GNU Project The GNU toolchain is a blanket term for a collection of Programming tools produced by the GNU Project. The GNU C Library, commonly known as glibc, is the C standard library released by the GNU Project. The GNU Core Utilities or coreutils is a package of GNU Software containing many of the basic tools such as cat, Ls

Linux distributions, comprising Linux and large collections of compatible software have become popular both with individual users and in business. Popular distributions include Red Hat Enterprise Linux, Fedora, SUSE Linux Enterprise, openSUSE, Debian GNU/Linux, Ubuntu, Mandriva Linux, Slackware Linux and Gentoo. Red Hat Enterprise Linux is a Linux distribution produced by Red Hat and targeted toward the commercial market including mainframes. The Fedora Operating system is an RPM -based general purpose Linux distribution, developed by the community-supported Fedora Project and sponsored SUSE (ˈsuːsə German ˈzuːzə is a major retail Operating system, produced worldwide and supported by Novell Inc SUSE Linux distributions openSUSE, (ˌoʊpɛnˈsuːzə is a general purpose Operating system developed by the OpenSUSE Project. Debian ( pronounced) is a computer Operating system composed entirely of Free and open source software. Ubuntu Kubuntu Edubuntu Xubuntu Gobuntu --> Ubuntu Mandriva Linux (formerly Mandrakelinux or Mandrake Linux) is an Operating system created by Mandriva (formerly Mandrakesoft Slackware is an Operating system created by Patrick Volkerding of Slackware Linux Inc The Gentoo Linux Operating system (ˈdʒɛntuː is a Linux distribution based on the Portage Package management system.

A free derivative of BSD Unix, 386BSD, was also released in 1992 and led to the NetBSD and FreeBSD projects. 386BSD, sometimes called " JOLIX " is a free BSD Unix Operating system for PC compatible computer systems based NetBSD is a freely redistributable Open source version of the Unix -derivative Berkeley Software Distribution (BSD Computer Operating FreeBSD is a Unix-like free Operating system descended from AT&T UNIX via the Berkeley Software Distribution (BSD branch through With the 1994 settlement of a lawsuit that UNIX Systems Laboratories brought against the University of California and Berkeley Software Design Inc. Unix System Laboratories or USL was originally organized as part of Bell Labs in 1989 (USL v. BSDi), it was clarified that Berkeley had the right to distribute BSD Unix — for free, if it so desired. USL v BSDi was a Lawsuit brought in the United States in 1992 by Unix System Laboratories against Berkeley Software Design, Inc and the Since then, BSD Unix has been developed in several different directions, including OpenBSD and DragonFly BSD. OpenBSD is a Unix-like computer Operating system descended from Berkeley Software Distribution (BSD a Unix derivative developed at the DragonFly BSD is a free Unix-like operating system created as a fork of FreeBSD 4

Linux and BSD are now rapidly occupying much of the market traditionally occupied by proprietary Unix operating systems, as well as expanding into new markets such as the consumer desktop and mobile and embedded devices. Due to the modularity of the Unix design, sharing bits and pieces is relatively common; consequently, most or all Unix and Unix-like systems include at least some BSD code, and modern systems also usually include some GNU utilities in their distribution.

In 2005, Sun Microsystems released the bulk of the source code to the Solaris operating system, a System V variant, under the name OpenSolaris, making it the first actively developed commercial Unix system to be open sourced (several years earlier, Caldera had released many of the older Unix systems under an educational and later BSD license). Sun Microsystems Inc ( is a multinational vendor of Computers computer components Computer software, and Information technology services Solaris is a Unix -based Operating system introduced by Sun Microsystems in 1992 as the successor to SunOS. OpenSolaris is an Open source project created by Sun Microsystems to build a developer community around Solaris Operating System technology Open source is a development methodology which offers practical accessibility to a product's source (goods and knowledge BSD licenses represent a family of Permissive free software licences. As a result, a great deal of formerly proprietary AT&T/USL code is now freely available.

Branding

See also: list of Unix systems

In October 1993, Novell, the company that owned the rights to the Unix System V source at the time, transferred the trademarks of Unix to the X/Open Company (now The Open Group),^[13] and in 1995 sold the related business operations to Santa Cruz Operation. Each version of the UNIX Time-Sharing System evolved from the version before with version one evolving from the prototypal Unics. Novell Inc ( is a global Software Corporation based in the United States specializing in enterprise operating systems such as SUSE A trademark or trade mark, represented by the symbols ™ and ®, or mark is a distinctive sign or indicator used by an individual The Open Group is an industry Consortium to set vendor- and technology-neutral open standards for Computing infrastructure Santa Cruz Operation ( SCO) was a Software company based in Santa Cruz California which was best known for selling three Unix variants for ^[14] Whether Novell also sold the copyrights to the actual software was the subject of a 2006 federal lawsuit, SCO v. Novell, which Novell won; the case is being appealed. Copyright is a legal concept enacted by Governments, giving the creator of an original work of authorship Exclusive rights to control its distribution usually for SCO v Novell is a lawsuit brought by the SCO Group against Novell. Unix vendor SCO Group Inc. accused Novell of slander of title. The SCO Group Inc ( TSG, informally SCO;) is a software company formerly called Caldera Systems and Caldera International. Novell Inc ( is a global Software Corporation based in the United States specializing in enterprise operating systems such as SUSE In law slander of title is normally a claim involving Real estate in which one entity falsely claims to own another entity's property

The present owner of the trademark UNIX® is The Open Group, an industry standards consortium. A trademark or trade mark, represented by the symbols ™ and ®, or mark is a distinctive sign or indicator used by an individual The Open Group is an industry Consortium to set vendor- and technology-neutral open standards for Computing infrastructure Only systems fully compliant with and certified to the Single UNIX Specification qualify as "UNIX®" (others are called "Unix system-like" or "Unix-like"). The Single UNIX Specification ( SUS) is the collective name of a family of standards for Computer Operating systems to qualify for the name " Unix A Unix-like (sometimes shortened to *nix) Operating system is one that behaves in a manner similar to a Unix system while not necessarily conforming

By decree of The Open Group, the term "UNIX®" refers more to a class of operating systems than to a specific implementation of an operating system; those operating systems which meet The Open Group's Single UNIX Specification should be able to bear the UNIX® 98 or UNIX® 03 trademarks today, after the operating system's vendor pays a fee to The Open Group. The Single UNIX Specification ( SUS) is the collective name of a family of standards for Computer Operating systems to qualify for the name " Unix The Single UNIX Specification ( SUS) is the collective name of a family of standards for Computer Operating systems to qualify for the name " Unix The Single UNIX Specification ( SUS) is the collective name of a family of standards for Computer Operating systems to qualify for the name " Unix Systems licensed to use the UNIX® trademark include AIX, HP-UX, IRIX, Solaris, Tru64 (formerly "Digital UNIX"), A/UX, Mac OS X 10. HP-UX (Hewlett Packard UniX is Hewlett-Packard 's proprietary implementation of the Unix Operating system, based on System V (initially IRIX is a computer Operating system developed by Silicon Graphics Inc Solaris is a Unix -based Operating system introduced by Sun Microsystems in 1992 as the successor to SunOS. Tru64 UNIX is a 64-bit UNIX Operating system for the Alpha Microprocessor architecture currently owned by Hewlett-Packard A/UX (from A pple U ni' x') was Apple Computer 's implementation of the Unix Operating system for some of their Macintosh Mac OS X (mæk oʊ ɛs tɛn is a line of computer Operating systems developed marketed and sold by Apple Inc, the latest of which is pre-loaded on all currently 5 on Intel platforms,^[15] and a part of z/OS. z/OS is a 64-bit Operating system for Mainframe computers, created by IBM.

Sometimes a representation like "Un*x", "*NIX", or "*N?X" is used to indicate all operating systems similar to Unix. This comes from the use of the "*" and "?" characters as "wildcard" characters in many utilities. This notation is also used to describe other Unix-like systems, e. g. Linux, BSD, etc. , that have not met the requirements for UNIX® branding from the Open Group.

The Open Group requests that "UNIX®" is always used as an adjective followed by a generic term such as "system" to help avoid the creation of a genericized trademark. A genericized trademark (also known as a generic trademark or proprietary eponym) is a Trademark or Brand name that has become the colloquial

"Unix" was the original formatting, but the usage of "UNIX" remains widespread because, according to Dennis Ritchie, when presenting the original Unix paper to the third Operating Systems Symposium of the American Association for Computing Machinery, “we had a new typesetter and troff had just been invented and we were intoxicated by being able to produce small caps. Dennis MacAlistair Ritchie (born September 9, 1941) is an American computer scientist notable for his influence on C and other Programming The Association for Computing Machinery, or ACM, was founded in 1947 as the world's first scientific and educational Computing society ”^[16] Many of the operating system's predecessors and contemporaries used all-uppercase lettering, so many people wrote the name in upper case due to force of habit.

Several plural forms of Unix are used to refer to multiple brands of Unix and Unix-like systems. Most common is the conventional "Unixes", but the hacker culture which created Unix has a penchant for playful use of language, and "Unices" (treating Unix as Latin noun of the third declension) is also popular. In Computing, hacker has several meanings A community of enthusiast Computer programmers and Systems designers originated in the 1960s Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Latin is an inflected language and as such its nouns pronouns and adjectives must be declined in order to serve a grammatical function The Anglo-Saxon plural form "Unixen" is not common, although occasionally seen. Trademark names can be registered by different entities in different countries and trademark laws in some countries allow the same trademark name to be controlled by two different entities if each entity uses the trademark in easily distinguishable categories. The result is that Unix has been used as a brand name for various products including book shelves, ink pens, bottled glue, diapers, hair driers and food containers. ^[17]

Common Unix commands

See also: List of Unix utilities

Widely used Unix commands include:

• Directory and file creation and navigation: ls cd pwd mkdir rm rmdir cp find touch mv
• File viewing and editing: more less ed vi emacs head tail
• Text processing: echo cat grep sort uniq sed awk cut tr split printf
• File comparison: comm cmp diff patch
• Miscellaneous shell tools: yes test xargs
• System administration: chmod chown ps su w who
• Communication: mail telnet ftp finger ssh
• Authentication: su login passwd

References

External links

• The Unix Tree: files from historic releases
• The Unix Guru Universe
• The Unix Heritage Society
• A more complete map of the different Unices and derivatives
• What is UNIX, Anyway?
• The Creation of the UNIX Operating System
• UNIX Evolution by Ian F. Darwin and Geoffrey Collyer
• Unix at the Open Directory Project
• The Open Group UNIX System Homepage
• Unix History
• The Unix Acronym List
• Unix As Literature
• Unix History A large graphical family tree of Unixes
• SDF Public Access UNIX System
• The Unix Forums
• Unix Power
• A very interesting Unix tutorial by Douglas Wilhelm Harder, from the University of Waterloo
• The UNIX-Haters' Handbook. The Open Directory Project ( ODP) also known as dmoz (from directory An uncomplimentary anthology of early (and oft-forgotten) Unix history as revealed by web posts of early users.