Unix

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Unix_table_infobox_0

UnixUnix_table_caption_0
DeveloperUnix_header_cell_0_0_0 Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna at Bell LabsUnix_cell_0_0_1
Written inUnix_header_cell_0_1_0 C and assembly languageUnix_cell_0_1_1
OS familyUnix_header_cell_0_2_0 UnixUnix_cell_0_2_1
Working stateUnix_header_cell_0_3_0 CurrentUnix_cell_0_3_1
Source modelUnix_header_cell_0_4_0 Historically proprietary software, while some Unix projects (including BSD family and illumos) are open-sourceUnix_cell_0_4_1
Initial releaseUnix_header_cell_0_5_0 Development started in 1969

First manual published internally in November 1971 (1971-11) Announced outside Bell Labs in October 1973 (1973-10)Unix_cell_0_5_1

Available inUnix_header_cell_0_6_0 EnglishUnix_cell_0_6_1
Kernel typeUnix_header_cell_0_7_0 Varies; monolithic, microkernel, hybridUnix_cell_0_7_1
Default user interfaceUnix_header_cell_0_8_0 Command-line interface and Graphical (Wayland and X Window System; Android SurfaceFlinger; macOS Quartz)Unix_cell_0_8_1
LicenseUnix_header_cell_0_9_0 Varies; some versions are proprietary, others are free/open-source softwareUnix_cell_0_9_1
Official websiteUnix_header_cell_0_10_0 Unix_cell_0_10_1

Unix (/ˈjuːnɪks/; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, development starting in the 1970s at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and others. Unix_sentence_0

Initially intended for use inside the Bell System, AT&T licensed Unix to outside parties in the late 1970s, leading to a variety of both academic and commercial Unix variants from vendors including University of California, Berkeley (BSD), Microsoft (Xenix), Sun Microsystems (SunOS/Solaris), HP/HPE (HP-UX), and IBM (AIX). Unix_sentence_1

In the early 1990s, AT&T sold its rights in Unix to Novell, which then sold its Unix business to the Santa Cruz Operation (SCO) in 1995. Unix_sentence_2

The UNIX trademark passed to The Open Group, a neutral industry consortium founded in 1996, which allows the use of the mark for certified operating systems that comply with the Single UNIX Specification (SUS). Unix_sentence_3

However, Novell continues to own the Unix copyrights, which the SCO Group, Inc. v. Novell, Inc. court case (2010) confirmed. Unix_sentence_4

Unix systems are characterized by a modular design that is sometimes called the "Unix philosophy". Unix_sentence_5

According to this philosophy, the operating system should provide a set of simple tools, each of which performs a limited, well-defined function. Unix_sentence_6

A unified (the ) and an inter-process communication mechanism known as "pipes" serve as the main means of communication, and a shell scripting and command language (the Unix shell) is used to combine the tools to perform complex workflows. Unix_sentence_7

Unix distinguishes itself from its predecessors as the first portable operating system: almost the entire operating system is written in the C programming language, which allows Unix to operate on numerous platforms. Unix_sentence_8

Overview Unix_section_0

Unix was originally meant to be a convenient platform for programmers developing software to be run on it and on other systems, rather than for non-programmers. Unix_sentence_9

The system grew larger as the operating system started spreading in academic circles, and as users added their own tools to the system and shared them with colleagues. Unix_sentence_10

At first, Unix was not designed to be portable or for multi-tasking. Unix_sentence_11

Later, Unix gradually gained portability, multi-tasking and multi-user capabilities in a time-sharing configuration. Unix_sentence_12

Unix systems are characterized by various concepts: the use of plain text for storing data; a hierarchical ; 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. Unix_sentence_13

These concepts are collectively known as the "Unix philosophy". Unix_sentence_14

Brian Kernighan and Rob Pike summarize this in The Unix Programming Environment as "the idea that the power of a system comes more from the relationships among programs than from the programs themselves". Unix_sentence_15

By the early 1980s, users began seeing Unix as a potential universal operating system, suitable for computers of all sizes. Unix_sentence_16

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. Unix_sentence_17

Both Unix and the C programming language were developed by AT&T and distributed to government and academic institutions, which led to both being ported to a wider variety of machine families than any other operating system. Unix_sentence_18

The Unix operating system consists of many libraries and utilities along with the master control program, the kernel. Unix_sentence_19

The kernel provides services to start and stop programs, handles the and other common "low-level" tasks that most programs share, and schedules access to avoid conflicts when programs try to access the same resource or device simultaneously. Unix_sentence_20

To mediate such access, the kernel has special rights, reflected in the distinction of kernel space from user space, the latter being a priority realm where most application programs operate. Unix_sentence_21

History Unix_section_1

Main article: History of Unix Unix_sentence_22

The origins of Unix date back to the mid-1960s when the Massachusetts Institute of Technology, Bell Labs, and General Electric were developing Multics, a time-sharing operating system for the GE-645 mainframe computer. Unix_sentence_23

Multics featured several innovations, but also presented severe problems. Unix_sentence_24

Frustrated by the size and complexity of Multics, but not by its goals, individual researchers at Bell Labs started withdrawing from the project. Unix_sentence_25

The last to leave were Ken Thompson, Dennis Ritchie, Douglas McIlroy, and Joe Ossanna, who decided to reimplement their experiences in a new project of smaller scale. Unix_sentence_26

This new operating system was initially without organizational backing, and also without a name. Unix_sentence_27

The new operating system was a single-tasking system. Unix_sentence_28

In 1970, the group coined the name Unics for Uniplexed Information and Computing Service as a pun on Multics, which stood for Multiplexed Information and Computer Services. Unix_sentence_29

Brian Kernighan takes credit for the idea, but adds that "no one can remember" the origin of the final spelling Unix. Unix_sentence_30

Dennis Ritchie, Doug McIlroy, and Peter G. Neumann also credit Kernighan. Unix_sentence_31

The operating system was originally written in assembly language, but in 1973, Version 4 Unix was rewritten in C. Unix_sentence_32

Version 4 Unix, however, still had many PDP-11 dependent codes, and was not suitable for porting. Unix_sentence_33

The first port to another platform was made five years later (1978) for the Interdata 8/32. Unix_sentence_34

Bell Labs produced several versions of Unix that are collectively referred to as "Research Unix". Unix_sentence_35

In 1975, the first source license for UNIX was sold to Donald B. Gillies at the University of Illinois at Urbana–Champaign Department of Computer Science. Unix_sentence_36

UIUC graduate student Greg Chesson, who had worked on the UNIX kernel at Bell Labs, was instrumental in negotiating the terms of the license. Unix_sentence_37

During the late 1970s and early 1980s, the influence of Unix in academic circles led to large-scale adoption of Unix (BSD and System V) by commercial startups, which in turn led to Unix fragmenting into multiple, similar but often slightly mutually-incompatible systems including DYNIX, HP-UX, SunOS/Solaris, AIX, and Xenix. Unix_sentence_38

In the late 1980s, AT&T Unix System Laboratories and Sun Microsystems developed System V Release 4 (SVR4), which was subsequently adopted by many commercial Unix vendors. Unix_sentence_39

In the 1990s, Unix and Unix-like systems grew in popularity and became the operating system of choice for over 90% of the world's top 500 fastest supercomputers, as BSD and Linux distributions were developed through collaboration by a worldwide network of programmers. Unix_sentence_40

In 2000, Apple released Darwin, also a Unix system, which became the core of the Mac OS X operating system, later renamed macOS. Unix_sentence_41

Unix operating systems are widely used in modern servers, workstations, and mobile devices. Unix_sentence_42

Standards Unix_section_2

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. Unix_sentence_43

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 (SUS) administered by The Open Group. Unix_sentence_44

Starting in 1998, the Open Group and IEEE started the Austin Group, to provide a common definition of POSIX and the Single UNIX Specification, which, by 2008, had become the Open Group Base Specification. Unix_sentence_45

In 1999, in an effort towards compatibility, several Unix system vendors agreed on SVR4's Executable and Linkable Format (ELF) as the standard for binary and object code files. Unix_sentence_46

The common format allows substantial binary compatibility among different Unix systems operating on the same CPU architecture. Unix_sentence_47

The was created to provide a reference directory layout for Unix-like operating systems; it has mainly been used in Linux. Unix_sentence_48

Components Unix_section_3

See also: List of Unix commands Unix_sentence_49

Impact Unix_section_4

See also: Unix-like Unix_sentence_50

Branding Unix_section_5

See also: List of Unix systems Unix_sentence_51

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), and in 1995 sold the related business operations to Santa Cruz Operation (SCO). Unix_sentence_52

Whether Novell also sold the copyrights to the actual software was the subject of a federal lawsuit in 2006, SCO v. Novell, which Novell won. Unix_sentence_53

The case was appealed, but on August 30, 2011, the United States Court of Appeals for the Tenth Circuit affirmed the trial decisions, closing the case. Unix_sentence_54

Unix vendor SCO Group Inc. accused Novell of slander of title. Unix_sentence_55

The present owner of the trademark UNIX is The Open Group, an industry standards consortium. Unix_sentence_56

Only systems fully compliant with and certified to the Single UNIX Specification qualify as "UNIX" (others are called "Unix-like"). Unix_sentence_57

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 substantial certification fee and annual trademark royalties to The Open Group. Unix_sentence_58

Systems that have been licensed to use the UNIX trademark include AIX, EulerOS, HP-UX, Inspur K-UX, IRIX, macOS, Solaris, Tru64 UNIX (formerly "Digital UNIX", or OSF/1), and z/OS. Unix_sentence_59

Notably, EulerOS and Inspur K-UX are Linux distributions certified as UNIX 03 compliant. Unix_sentence_60

Sometimes a representation like Un*x, *NIX, or *N?X is used to indicate all operating systems similar to Unix. Unix_sentence_61

This comes from the use of the asterisk (*) and the question mark characters as wildcard indicators in many utilities. Unix_sentence_62

This notation is also used to describe other Unix-like systems that have not met the requirements for UNIX branding from the Open Group. Unix_sentence_63

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. Unix_sentence_64

Unix was the original formatting, but the usage of UNIX remains widespread because it was once typeset in small caps (Unix). Unix_sentence_65

According to Dennis Ritchie, when presenting the original Unix paper to the third Operating Systems Symposium of the American Association for Computing Machinery (ACM), "we had a new typesetter and troff had just been invented and we were intoxicated by being able to produce small caps". Unix_sentence_66

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. Unix_sentence_67

It is not an acronym. Unix_sentence_68

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. Unix_sentence_69

The result is that Unix has been used as a brand name for various products including bookshelves, ink pens, bottled glue, diapers, hair driers and food containers. Unix_sentence_70

Several plural forms of Unix are used casually to refer to multiple brands of Unix and Unix-like systems. Unix_sentence_71

Most common is the conventional Unixes, but Unices, treating Unix as a Latin noun of the third declension, is also popular. Unix_sentence_72

The pseudo-Anglo-Saxon plural form Unixen is not common, although occasionally seen. Unix_sentence_73

Sun Microsystems, developer of the Solaris variant, has asserted that the term Unix is itself plural, referencing its many implementations. Unix_sentence_74

See also Unix_section_6

Unix_unordered_list_0


Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Unix.