A Unix-like (sometimes shortened to *nix to circumvent trademark Unix is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna. Today's Unix systems are split into various branches, developed over time by AT&T as well as various commercial vendors and non-profit issues) operating system An operating system is the software on a computer that manages the way different programs use its hardware, and regulates the ways that a user controls the computer. Operating systems are found on almost any device that contains a computer with multiple programs—from cellular phones and video game consoles to supercomputers and web servers. Some is one that behaves in a manner similar to a Unix Unix is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna. Today's Unix systems are split into various branches, developed over time by AT&T as well as various commercial vendors and non-profit system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification The Single UNIX Specification is the collective name of a family of standards for computer operating systems to qualify for the name "Unix". The SUS is developed and maintained by the Austin Group, based on earlier work by the IEEE and The Open Group.

There is no standard A technical standard is an established norm or requirement. It is usually a formal document that establishes uniform engineering or technical criteria, methods, processes and practices. In contrast, a custom, convention, company product, corporate standard, etc. which becomes generally accepted and dominant is often called a de facto standard for defining the term, and some difference of opinion is possible as to the degree to which a given OS is "Unix-like".

The term can include free and open source Free and open source software, also F/OSS, FOSS, or FLOSS is software that is liberally licensed to grant the right of users to use, study, change, and improve its design through the availability of its source code. This approach has gained both momentum and acceptance as the potential benefits have been increasingly recognized by both individuals operating systems inspired by Bell Labs Bell Laboratories is the research and development organization of Alcatel-Lucent and previously of the American Telephone & Telegraph Company (AT&T)’ Unix or designed to emulate its features, commercial and proprietary work-alikes, and even versions based on the licensed A software license is a legal instrument (by way of contract law) governing the usage or redistribution of software. All software is copyright protected, except material in the public domain. Contractual confidentiality is another way of protecting software. A typical software license grants an end-user permission to use one or more copies of UNIX source code (which may be sufficiently "Unix-like" to pass certification and bear the "UNIX" trademark).

Free and open source examples are sometimes known as Freenix.^[1]

The term "Unix-like" and the UNIX trademark

The Open Group The Open Group is an industry consortium to set vendor- and technology-neutral open standards for computing infrastructure. It was formed when X/Open merged with the Open Software Foundation in 1996. The Open Group is most famous as the certifying body for the UNIX trademark, in the past the group was best known for its publication of the Single owns the UNIX Unix is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna. Today's Unix systems are split into various branches, developed over time by AT&T as well as various commercial vendors and non-profit trademark A trademark or trade mark is a distinctive sign or indicator used by an individual, business organization, or other legal entity to identify that the products or services to consumers with which the trademark appears originate from a unique source, and to distinguish its products or services from those of other entities and administers the Single UNIX Specification, with the "UNIX" name being used as a certification mark On the part of the certifier, the label itself is a type of trademark whereby the listee, or manufacturer, uses the mark to indicate eligibility of the products for use in field installations in accordance with the requirements of the code, and/or the origin, material, mode of manufacture of products, mode of performance of services, quality,. They do not approve of the construction "Unix-like", and consider it misuse of their trademark. Their guidelines require "UNIX" to be presented in uppercase or otherwise distinguished from the surrounding text, strongly encourage using it as a branding adjective for a generic word such as "system", and discourage its use in hyphenated phrases.^[2]

Other parties frequently treat "Unix" as a genericized trademark A genericized trademark is a trademark or brand name that has become the colloquial or generic description for or synonymous with a general class of product or service, rather than the specific meaning intended by the trademark's holder. Using a genericized trademark to refer to the general form of what that trademark represents is a form of. Some add a wildcard character In telecommunications, a wildcard character is a character that may be substituted for any of a defined subset of all possible characters to the name to make a euphemistic A euphemism is a substitution with an agreeable or less offensive expression in place of one that may offend or suggest something unpleasant to the receiver, or to make it less troublesome for the speaker, as in the case of doublespeak. The deployment of euphemisms is a central aspect within the public application of political correctness abbreviation like "Un*x"^[3] or the more common "*nix", since Unix-like systems often have Unix-like names such as AIX AIX is the name given to a series of proprietary operating systems sold by IBM for several of its computer system platforms, based on UNIX System V with 4.3BSD-compatible extensions, HP-UX HP-UX is Hewlett-Packard's proprietary implementation of the Unix operating system, based on System V (initially System III). It runs on the HP 9000 PA-RISC-based range of processors and HP Integrity systems that are based on Intel's Itanium-processors. HP-UX was also available for later Apollo/Domain systems, and earlier versions ran on the HP 900, IRIX IRIX is a computer operating system developed by Silicon Graphics, Inc. to run natively on their 32- and 64-bit MIPS architecture workstations and servers. It is based on UNIX System V with BSD extensions. IRIX is the origin of the XFS file system, Linux Linux refers to the family of Unix-like computer operating systems using the Linux kernel. Linux can be installed on a wide variety of computer hardware, ranging from mobile phones, tablet computers and video game consoles, to mainframes and supercomputers. Linux is predominantly known for its use in servers; in 2009 it held a server market share, Minix MINIX is a Unix-like computer operating system based on a microkernel architecture created by Andrew S. Tanenbaum for educational purposes; MINIX also inspired the creation of the Linux kernel, Ultrix Ultrix was the brand name of Digital Equipment Corporation's (DEC) native Unix systems. While ultrix is the Latin word for avenger, the name was chosen solely for its sound.[citation needed], and Xenix Xenix is a version of the Unix operating system, licensed by Microsoft from AT&T in the late 1970s. The Santa Cruz Operation later acquired exclusive rights to the software, and eventually began distributing it as SCO UNIX (now known as SCO OpenServer). These patterns do not literally match many system names, but are still generally recognized to refer to any UNIX descendant or work-alike system, even those with completely dissimilar names such as Solaris Oracle Solaris is a UNIX-based operating system introduced by Sun Microsystems in 1992 as the successor to SunOS, FreeBSD FreeBSD is a free Unix-like operating system descended from AT&T UNIX via the Berkeley Software Distribution . It has been characterized as "the unknown giant among free operating systems". It is not a clone of UNIX, but works like UNIX, with UNIX-compliant internals and system APIs. FreeBSD is generally regarded as reliable and or Mac OS X Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, Mac OS X has been included with all new Macintosh computer systems. It is the successor to Mac OS 9, the final release of the "classic" Mac OS, which had been Apple's primary operating system since 198.

As of 2007, there is an active legal battle between Wayne R. Gray and Open Group that centers on the use of UNIX as a trademark.^[4] Trademark Trial and Appeal Board court documents indicate that Gray’s legal team is seeking for the Open Group to provide documentation for their trademark claim.

Also in 2007, the Open Group reached a binding legal agreement to prevent the German University of Kassel from using "UNIK" as its short form name.^[5]

Categories

Dennis Ritchie Dennis MacAlistair Ritchie is an American computer scientist notable for his influence on C and other programming languages, and on operating systems such as Multics and Unix. He received the Turing Award in 1983 and the National Medal of Technology in 1998. Ritchie was the head of Lucent Technologies System Software Research Department when he, one of the original creators of Unix, has expressed his opinion that Unix-like systems such as GNU GNU (pronounced /ˈɡnuː/ ) is a Unix-like computer operating system developed by the GNU project, ultimately aiming to be a "complete Unix-compatible software system" composed wholly of free software. Development of GNU was initiated by Richard Stallman in 1983 and was the original focus of the Free Software Foundation (FSF), but no/Linux Linux refers to the family of Unix-like computer operating systems using the Linux kernel. Linux can be installed on a wide variety of computer hardware, ranging from mobile phones, tablet computers and video game consoles, to mainframes and supercomputers. Linux is predominantly known for its use in servers; in 2009 it held a server market share are de facto De facto is a Latin expression that means "by [the] fact". In law, it is meant to mean "in practice but not necessarily ordained by law" or "in practice or actuality, but without being officially established". It is commonly used in contrast to de jure when referring to matters of law, governance, or technique (such Unix systems.^[6] Eric S. Raymond Eric Steven Raymond , often referred to as ESR, is a computer programmer, author and open source software advocate. His name became known within the hacker culture when he picked up maintenance of the "Jargon File" in 1990. After the 1997 publication of "The Cathedral and the Bazaar", Raymond became, for a number of years, an and Rob Langley have suggested^[7] that there are three kinds of Unix-like systems:

Genetic UNIX

Those systems with a historical connection to the AT&T AT&T Inc. is the largest provider of fixed telephony in the United States, and also provides broadband and subscription television services. AT&T is the second largest provider of mobile telephony service in the United States, with over 85.1 million wireless customers, and more than 210 million total customers codebase. Most (but not all) commercial UNIX systems fall into this category. So do the BSD Berkeley Software Distribution is the UNIX operating system derivative developed and distributed by the Computer Systems Research Group (CSRG) of the University of California, Berkeley, from 1977 to 1995 systems, which are descendants of work done at the University of California, Berkeley The University of California, Berkeley , is a public research university located in Berkeley, California, United States. The oldest of the ten major campuses affiliated with the University of California, Berkeley offers some 300 undergraduate and graduate degree programs in a wide range of disciplines. The university occupies 6,651 acres (2,692 ha) in the late 1970s and early 1980s. Some of these systems have no original AT&T code but can still trace their ancestry to AT&T designs.

Trademark or Branded UNIX

These systems—largely commercial in nature—have been determined by the Open Group to meet the Single UNIX Specification The Single UNIX Specification is the collective name of a family of standards for computer operating systems to qualify for the name "Unix". The SUS is developed and maintained by the Austin Group, based on earlier work by the IEEE and The Open Group and are allowed to carry the UNIX name. Most such systems are commercial derivatives of the System V Unix System V, commonly abbreviated SysV , is one of the versions of the Unix operating system. It was originally developed by American Telephone & Telegraph (AT&T) and first released in 1983. Four major versions of System V were released, termed Releases 1, 2, 3 and 4. System V Release 4, or SVR4, was commercially the most successful code base in one form or another, though a few (such as IBM z/OS z/OS is a 64-bit operating system for mainframe computers, created by IBM. It is the successor to OS/390, which in turn followed MVS and combined a number of formerly separate, related products. z/OS offers the attributes of modern operating systems but also retains much of the functionality originating in the 1960s and each subsequent decade that) earned the trademark through a POSIX POSIX or "Portable Operating System Interface [for Unix]" is the name of a family of related standards specified by the IEEE to define the application programming interface (API), along with shell and utilities interfaces for software compatible with variants of the Unix operating system, although the standard can apply to any operating compatibility layer and are not otherwise inherently Unix systems. (Apple Mac OS X Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, Mac OS X has been included with all new Macintosh computer systems. It is the successor to Mac OS 9, the final release of the "classic" Mac OS, which had been Apple's primary operating system since 198 10.5 Mac OS X Leopard is the sixth major release of Mac OS X, Apple’s desktop and server operating system for Macintosh computers. Leopard was released on 26 October 2007 as the successor of Mac OS X Tiger (version 10.4), and is available in two variants: a desktop version suitable for personal computers, and a server version, Mac OS X Server. Steve and later is BSD Berkeley Software Distribution is the UNIX operating system derivative developed and distributed by the Computer Systems Research Group (CSRG) of the University of California, Berkeley, from 1977 to 1995, but has been certified.) Many ancient UNIX systems no longer meet this definition.

Functional UNIX

Broadly, any Unix-like system that behaves in a manner roughly consistent with the UNIX specification; more specifically, this can refer to systems such as Linux Linux refers to the family of Unix-like computer operating systems using the Linux kernel. Linux can be installed on a wide variety of computer hardware, ranging from mobile phones, tablet computers and video game consoles, to mainframes and supercomputers. Linux is predominantly known for its use in servers; in 2009 it held a server market share or Minix MINIX is a Unix-like computer operating system based on a microkernel architecture created by Andrew S. Tanenbaum for educational purposes; MINIX also inspired the creation of the Linux kernel that behave similarly to a UNIX system but have no genetic or trademark connection to the AT&T code base. Most free/open-source implementations of the UNIX design, whether genetic UNIX or not, fall into the restricted definition of this third category due to the expense of obtaining Open Group certification, which costs thousands of dollars, not being commercially necessary.

Compatibility layers

Some non-Unix-like operating systems provide a Unix-like compatibility layer, with variable degrees of Unix-like functionality.

• IBM z/OS z/OS is a 64-bit operating system for mainframe computers, created by IBM. It is the successor to OS/390, which in turn followed MVS and combined a number of formerly separate, related products. z/OS offers the attributes of modern operating systems but also retains much of the functionality originating in the 1960s and each subsequent decade that's POSIX compatibility layer is sufficiently complete to be certified as trademark UNIX.
• Cygwin Cygwin is a Unix-like environment and command-line interface for Microsoft Windows. Cygwin provides native integration of Windows-based applications, data, and other system resources with applications, software tools, and data of the Unix-like environment. Thus it is possible to launch Windows applications from the Cygwin environment, as well as provides a reasonably complete GNU GNU (pronounced /ˈɡnuː/ ) is a Unix-like computer operating system developed by the GNU project, ultimately aiming to be a "complete Unix-compatible software system" composed wholly of free software. Development of GNU was initiated by Richard Stallman in 1983 and was the original focus of the Free Software Foundation (FSF), but no environment, sufficient for much common open source Open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology. Before the term open source became widely adopted, developers and producers used a variety of phrases to describe the concept; open source software to be compiled and run, with some emulation of Linux Linux refers to the family of Unix-like computer operating systems using the Linux kernel. Linux can be installed on a wide variety of computer hardware, ranging from mobile phones, tablet computers and video game consoles, to mainframes and supercomputers. Linux is predominantly known for its use in servers; in 2009 it held a server market share, on top of the Microsoft Windows Microsoft Windows is a series of software operating systems and graphical user interfaces produced by Microsoft. Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal user API The Windows API, informally WinAPI, is Microsoft's core set of application programming interfaces available in the Microsoft Windows operating systems. It was formerly called the Win32 API; however, the name Windows API more accurately reflects its roots in 16-bit Windows and its support on 64-bit Windows. Almost all Windows programs interact with.
• Interix Interix is the name of an optional, full-featured POSIX and Unix environment subsystem for Microsoft's Windows NT-based operating systems. It is a component of the Services for Unix release 3.0 and 3.5 (this last one is distributed freely). The most recent releases of Interix, 5.2 and 6.0, are components of the Windows Server 2003 R2, Windows provides Unix-like functionality as a Windows NT subsystem.

Development of Unix-like systems

"Unix-like" systems started to appear in the late 1970s and early 1980s. Many proprietary versions, such as Idris (1978), Coherent (1983), UNOS (1983), and UniFlex (1985), aimed to provide businesses with the functionality available to academic users of UNIX.

When AT&T later allowed commercial licensing of UNIX in the 1980s, a variety of proprietary systems were developed based on it, including AIX, HP-UX, IRIX, SunOS, Tru64, Ultrix, and Xenix. These largely displaced the proprietary clones. Growing incompatibility between these systems led to the creation of interoperability standards, including POSIX and the Single UNIX Specification.

Meanwhile, the GNU Project was launched in 1983 with the goal of making GNU, an operating system which all computer users could freely use, study, modify, and redistribute. Various "Unix-like" operating systems developed alongside GNU, frequently sharing substantial components with it (leading to some disagreement about whether they should be called "GNU" or not). These primarily served as low-cost and unrestricted substitutes for UNIX, and include 4.4BSD, Linux, and Minix. Some of these have in turn been the basis for commercial "Unix-like" systems, such as BSD/OS and Mac OS X. Notably, Mac OS X 10.5 and Mac OS X Server 10.5 are certified under the Single UNIX Specification.^[8]

The various BSD variants are notable in that they are in fact descendants of UNIX, developed by the University of California at Berkeley with UNIX source code from Bell Labs. However, the BSD code base has evolved since then, replacing all of the AT&T code. Since the BSD variants are not certified as compliant with the Single UNIX Specification (except for Mac OS X 10.5 Leopard and Mac OS X 10.6 Snow Leopard), they are referred to as "UNIX-like".

See also

• Berkeley Software Distribution
• Linux distribution
• List of Linux distributions
• List of Unix programs
• List of operating systems

References

1. ^ “FREENIX” has been used by the USENIX conferences to refer to Free and Open Source Software.[1]
2. ^ Trademark Guidelines, About The Open Group.
3. ^ Eric S. Raymond; Guy L. Steele Jr.. "UN*X". The Jargon File. http://catb.org/jargon/html/U/UN-asterisk-X.html. Retrieved 2009-01-22.
4. ^ TTABVUE. Trademark Trial and Appeal Board Inquiry System
5. ^ publik, Kasseler Hochschulzeitung, 2007-04-17
6. ^ Interview with Dennis M. Ritchie (Manuel Benet , LinuxFocus, July 1999)
7. ^ The meaning of 'Unix' (Eric Raymond and Rob Langley, OSI Position Paper on the SCO-vs.-IBM Complaint, 2003-03-10)
8. ^ Apple - Mac OS X Leopard - Technology - UNIX.

External links

• Unix-like Definition—by The Linux Information Project (LINFO)
• UNIX history—a history time line graph of most UNIX and Unix-like systems by Éric Lévénez
• Grokline's UNIX Ownership History Project—a project to map out the technical history of UNIX and Unix-like systems

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