Unix

Unix (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.

Thompson worked at Bell Labs for most of his career where he designed and implemented the original Unix operating system.

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), IBM (AIX), and Sun Microsystems (Solaris).

XENIX is a discontinued version of the UNIX operating system for various microcomputer platforms, licensed by Microsoft from AT&T Corporation in the late 1970s.

Unix (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.

He created the C programming language and, with long-time colleague Ken Thompson, the Unix operating system and B programming language.

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), IBM (AIX), and Sun Microsystems (Solaris).

Solaris is a non-free Unix operating system originally developed by Sun Microsystems.

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), IBM (AIX), and Sun Microsystems (Solaris).

Sun contributed significantly to the evolution of several key computing technologies, among them Unix, RISC processors, thin client computing, and virtualized computing.

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.

Santa Cruz Operation (SCO) was a software company based in Santa Cruz, California which was best known for selling three Unix variants for Intel x86 processors: Xenix, SCO UNIX (later known as SCO OpenServer), and UnixWare.

Unix systems are characterized by a modular design that is sometimes called the "Unix philosophy": the operating system provides a set of simple tools that each performs a limited, well-defined function, with a unified filesystem (the Unix filesystem) as the main means of communication, and a shell scripting and command language (the Unix shell) to combine the tools to perform complex workflows.

In Unix and operating systems inspired by it, the file system is considered a central component of the operating system.

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

The Open Group is the certifying body for the UNIX trademark, and publishes the Single UNIX Specification technical standard, which extends the POSIX standards.

As of 2014, the Unix version with the largest installed base is Apple's macOS.

macOS has a smaller usage share compared to Windows, but it also has traditionally more secure Unix roots.

Unix systems are characterized by a modular design that is sometimes called the "Unix philosophy": the operating system provides a set of simple tools that each performs a limited, well-defined function, with a unified filesystem (the Unix filesystem) as the main means of communication, and a shell scripting and command language (the Unix shell) to combine the tools to perform complex workflows.

It is based on the experience of leading developers of the Unix operating system.

Unix distinguishes itself from its predecessors as the first portable operating system: almost the entire operating system is written in the C programming language, thus allowing Unix to reach numerous platforms.

C was originally developed at Bell Labs by Dennis Ritchie between 1972 and 1973 to make utilities running on Unix.

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), IBM (AIX), and Sun Microsystems (Solaris).

Microsoft entered the operating system (OS) business in 1980 with its own version of Unix, called Xenix.

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".

He worked at Bell Labs and contributed to the development of Unix alongside Unix creators Ken Thompson and Dennis Ritchie.

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), IBM (AIX), and Sun Microsystems (Solaris).

Unix was created by alumnus Ken Thompson (BS 1965, MS 1966) along with colleague Dennis Ritchie.

As of 2014, the Unix version with the largest installed base is Apple's macOS.

By the 1990s, Apple was facing competition from OS/2 and UNIX vendors such as Sun Microsystems.

To mediate such access, the kernel has special rights, reflected in the division between user space and kernel space — although in microkernel implementations, like MINIX or Redox, functions such as network protocols may also run in user space.

MINIX (from "mini-Unix") is a POSIX-compliant (since version 2.0), Unix-like operating system based on a microkernel architecture.

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.

The concept of pipelines was championed by Douglas McIlroy at Unix's ancestral home of Bell Labs, during the development of Unix, shaping its toolbox philosophy.

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".

The Unix Programming Environment, first published in 1984 by Prentice Hall, is a book written by Brian W. Kernighan and Rob Pike, both of Bell Labs and considered an important and early document of the Unix operating system.

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.

Virtually all modern operating systems were heavily influenced by Multics – often through Unix, which was created by some of the people who had worked on Multics – either directly (Linux and macOS) or indirectly (Windows NT).

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".

He is best known for his work on the Go programming language and at Bell Labs, where he was a member of the Unix team and was involved in the creation of the Plan 9 from Bell Labs and Inferno operating systems, as well as the Limbo programming language.

Unix (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.

The GNU Project was started by activist and programmer Richard Stallman with the goal of creating a complete free software replacement to the proprietary UNIX operating system.

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

Research Unix refers to early versions of the Unix operating system for DEC PDP-7, PDP-11, VAX and Interdata 7/32 and 8/32 computers, developed in the Bell Labs Computing Sciences Research Center.

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.

On the server side, after their initial October 1991 Univel initiative Novell bought Unix System Laboratories (USL) from AT&T Corporation in 1993, acquiring rights to the Unix operating system for their UnixWare.

Unix systems are characterized by a modular design that is sometimes called the "Unix philosophy": the operating system provides a set of simple tools that each performs a limited, well-defined function, with a unified filesystem (the Unix filesystem) as the main means of communication, and a shell scripting and command language (the Unix shell) to combine the tools to perform complex workflows. 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.

Directory utilities may also include capabilities to create additional links to a directory (hard links in Unix), to rename parent links (".."

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), IBM (AIX), and Sun Microsystems (Solaris).

AIX (Advanced Interactive eXecutive, pronounced ) is a series of proprietary Unix operating systems developed and sold by IBM for several of its computer platforms.