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75-557: MACRO-11 was supported on all DEC PDP-11 operating systems. PDP-11 Unix systems also include an assembler (named as ), structurally similar to MACRO-11, but with different syntax and fewer features. The MACRO-11 assembler (and programs created by it) could also run under the RSX-11 compatibility mode of OpenVMS on VAX . A complete "Hello, World!" program in PDP-11 macro assembler, to run under RT-11 : The .MCALL pseudo-op warns

150-522: A read–eval–print loop, REPL ). Since the operating system shell is actually an application, it may easily be replaced with another similar application, for most operating systems. In addition to shells running on local systems, there are different ways to make remote systems available to local users; such approaches are usually referred to as remote access or remote administration. Initially available on multi-user mainframes , which provided text-based UIs for each active user simultaneously by means of

225-432: A teletypewriter can send codes representing keystrokes to a command interpreter program running on the computer; the command interpreter parses the sequence of keystrokes and responds with an error message if it cannot recognize the sequence of characters, or it may carry out some other program action such as loading an application program, listing files, logging in a user and many others. Operating systems such as UNIX have

300-688: A text terminal connected to the mainframe via serial line or modem , remote access has extended to Unix-like systems and Microsoft Windows. On Unix-like systems, Secure Shell protocol (SSH) is usually used for text-based shells, while SSH tunneling can be used for X Window System –based graphical user interfaces (GUIs). On Microsoft Windows, Remote Desktop Protocol can be used to provide GUI remote access, and since Windows Vista , PowerShell Remote can be used for text-based remote access via WMI, RPC, and WS-Management. Most operating system shells fall into one of two categories – command-line and graphical. Command-line shells provide

375-429: A time-sharing configuration, as well as portability. 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

450-484: A time-sharing operating system for the GE 645 mainframe computer. Multics featured several innovations , but also presented severe problems. Frustrated by the size and complexity of Multics, but not by its goals, individual researchers at Bell Labs started withdrawing from the project. The last to leave were Ken Thompson , Dennis Ritchie , Douglas McIlroy , and Joe Ossanna , who decided to reimplement their experiences in

525-519: A 1999 interview, Dennis Ritchie voiced his opinion that Linux and BSD Unix operating systems are a continuation of the basis of the Unix design and are derivatives of Unix: I think the Linux phenomenon is quite delightful, because it draws so strongly on the basis that Unix provided. Linux seems to be among the healthiest of the direct Unix derivatives, though there are also the various BSD systems as well as

600-424: A command-line interface (CLI) to the operating system, while graphical shells provide a graphical user interface (GUI). Other possibilities, although not so common, include a voice user interface and various implementations of a text-based user interface (TUI) that are not CLI, such as text-based menu systems. The relative merits of CLI- and GUI-based shells are often debated. Many computer users use both depending on

675-459: A command-line interface. For example, in Unix-like systems, the telnet program has a number of commands for controlling a link to a remote computer system. Since the commands to the program are made of the same keystrokes as the data being sent to a remote computer, some means of distinguishing the two are required. An escape sequence can be defined, using either a special local keystroke that

750-460: A convenient platform for programmers developing software to be run on it and on other systems, rather than for non-programmers. 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. At first, Unix was not designed to support multi-tasking or to be portable . Later, Unix gradually gained multi-tasking and multi-user capabilities in

825-424: A generic term such as system to help avoid the creation of a genericized trademark . Shell (computing) In computing , a shell is a computer program that exposes an operating system 's services to a human user or other programs. In general, operating system shells use either a command-line interface (CLI) or graphical user interface (GUI), depending on a computer's role and particular operation. It

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900-530: A large variety of shell programs with different commands, syntax and capabilities, with the POSIX shell being a baseline. Some operating systems had only a single style of command interface; commodity operating systems such as MS-DOS came with a standard command interface ( COMMAND.COM ) but third-party interfaces were also often available, providing additional features or functions such as menuing or remote program execution. Application programs may also implement

975-405: A new project of smaller scale. This new operating system was initially without organizational backing, and also without a name. The new operating system was a single-tasking system. 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 . Brian Kernighan takes credit for

1050-512: A potential universal operating system, suitable for computers of all sizes. 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. 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

1125-433: A purpose-built program. Several command-line shells, such as Nushell , Xonsh, Bash (Unix shell) , and Z shell , offer command-line completion , enabling the interpreter to expand commands based on a few characters input by the user. A command-line interpreter may offer a history function, so that the user can recall earlier commands issued to the system and repeat them, possibly with some editing. Since all commands to

1200-420: A reference directory layout for Unix-like operating systems; it has mainly been used in Linux. The Unix system is composed of several components that were originally packaged together. By including the development environment, libraries, documents and the portable, modifiable source code for all of these components, in addition to the kernel of an operating system, Unix was a self-contained software system. This

1275-504: 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 asterisk ( * ) and the question mark characters as wildcard indicators in many utilities. This notation is also used to describe other Unix-like systems that have not met the requirements for UNIX branding from the Open Group. The Open Group requests that UNIX always be used as an adjective followed by

1350-449: 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 TCP/IP networking protocols were quickly implemented on the Unix versions widely used on relatively inexpensive computers, which contributed to the Internet explosion of worldwide, real-time connectivity and formed

1425-419: A set of loosely coupled utilities. Most graphical user interfaces develop the metaphor of an "electronic desktop" , where data files are represented as if they were paper documents on a desk, and application programs similarly have graphical representations instead of being invoked by command names. Graphical shells typically build on top of a windowing system . In the case of X Window System or Wayland ,

1500-407: A shell communicates with the user via peripheral devices attached to the computer directly. Shells are actually special applications that use the kernel API in just the same way as it is used by other application programs. A shell manages the user–system interaction by prompting users for input, interpreting their input, and then handling output from the underlying operating system (much like

1575-487: A single monolithic program that includes all of the same functionality. These concepts are collectively known as the " Unix 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". By the early 1980s, users began seeing Unix as

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1650-544: A single nine-track magnetic tape , earning its reputation as a portable system. The printed documentation, typeset from the online sources, was contained in two volumes. The names and filesystem locations of the Unix components have changed substantially across the history of the system. Nonetheless, the V7 implementation has the canonical early structure: The Unix system had a significant impact on other operating systems. It achieved its reputation by its interactivity, by providing

1725-479: 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. The Plan 9 operating system pushed this model even further and eliminated the need for additional mechanisms. Unix also popularized the hierarchical file system with arbitrarily nested subdirectories, originally introduced by Multics. Other common operating systems of

1800-508: A versatile document preparation system, and an efficient file system featuring sophisticated access control, mountable and de-mountable volumes, and a unified treatment of peripherals as special files ." The latter permitted the Network Control Program (NCP) to be integrated within the Unix file system, treating network connections as special files that could be accessed through standard Unix I/O calls , which included

1875-402: A wider variety of machine families than any other operating system. The Unix operating system consists of many libraries and utilities along with the master control program, the kernel . The kernel provides services to start and stop programs, handles the file system and other common "low-level" tasks that most programs share, and schedules access to avoid conflicts when programs try to access

1950-543: Is " . ") For a more complicated example of MACRO-11 code, two examples chosen at random are Kevin Murrell's KPUN.MAC, or Farba Research's JULIAN routine. More extensive libraries of PDP-11 code can be found in the Metalab freeware and Trailing Edge archives. This programming-language -related article is a stub . You can help Misplaced Pages by expanding it . Unix Early research and development: Merging

2025-487: Is a good example of the former sort of application. LiteStep and Emerge Desktop are good examples of the latter. Interoperability programmes and purpose-designed software lets Windows users use equivalents of many of the various Unix-based GUIs discussed below, as well as Macintosh. An equivalent of the OS/2 Presentation Manager for version 3.0 can run some OS/2 programmes under some conditions using

2100-400: Is named a shell because it is the outermost layer around the operating system. Operating systems provide various services to their users, including file management , process management (running and terminating applications ), batch processing , and operating system monitoring and configuration. Most operating system shells are not direct interfaces to the underlying kernel , even if

2175-471: Is never passed on but always interpreted by the local system. The program becomes modal, switching between interpreting commands from the keyboard or passing keystrokes on as data to be processed. A feature of many command-line shells is the ability to save sequences of commands for re-use. A data file can contain sequences of commands which the CLI can be made to follow as if typed in by a user. Special features in

2250-609: The Bell Labs research center by Ken Thompson , Dennis Ritchie , and others. 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 ). Early versions of Unix ran on PDP-11 computers; Unix

2325-782: 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 distributions , consisting of the Linux kernel 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 , Ubuntu , Linux Mint , Slackware Linux , Arch Linux and Gentoo . A free derivative of BSD Unix, 386BSD ,

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2400-911: The Thompson shell in the first version of Unix. While simpler than the Multics shell, it contained some innovative features, which have been carried forward in modern shells, including the use of < and > for input and output redirection . The graphical shell first appeared in Douglas Engelbart ’s NLS system, demonstrated in December, 1968 at the Fall Joint Computer Conference in San Francisco, in what has been called The Mother of All Demos . Engelbart’s colleagues at Stanford Research Institute brought

2475-586: 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. 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 . Notably, EulerOS and Inspur K-UX are Linux distributions certified as UNIX 03 compliant. Sometimes

2550-443: The 95 and NT types at least through Windows XP. The interfaces of Windows versions 1 and 2 were markedly different. Desktop applications are also considered shells, as long as they use a third-party engine. Likewise, many individuals and developers dissatisfied with the interface of Windows Explorer have developed software that either alters the functioning and appearance of the shell or replaces it entirely. WindowBlinds by StarDock

2625-580: The CLI may apply when it is carrying out these stored instructions. Such batch files (script files) can be used repeatedly to automate routine operations such as initializing a set of programs when a system is restarted. Batch mode use of shells usually involves structures, conditionals, variables, and other elements of programming languages; some have the bare essentials needed for such a purpose, others are very sophisticated programming languages in and of themselves. Conversely, some programming languages can be used interactively from an operating system shell or in

2700-558: The Microsoft Windows operating system use the Windows shell as their shell. Windows Shell provides desktop environment , start menu , and task bar , as well as a graphical user interface for accessing the file management functions of the operating system. Older versions also include Program Manager , which was the shell for the 3.x series of Microsoft Windows, and which in fact shipped with later versions of Windows of both

2775-459: The OS/2 environmental subsystem in versions of Windows NT. "Shell" is also used loosely to describe application software that is "built around" a particular component, such as web browsers and email clients, in analogy to the shells found in nature. Indeed, the (command-line) shell encapsulates the operating system kernel . These are also sometimes referred to as "wrappers". In expert systems ,

2850-487: The Open Group Base Specification. 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. The common format allows substantial binary compatibility among different Unix systems operating on the same CPU architecture. The Filesystem Hierarchy Standard was created to provide

2925-491: The UNIX trademark to The Open Group , an industry consortium founded in 1996. The Open Group allows the use of the mark for certified operating systems that comply with the Single UNIX Specification (SUS). Unix-like operating systems have been relevant since the 1990s which function similarly to Unix: popular examples are GNU (including Linux ), FreeBSD and macOS . Unix was originally meant to be

3000-632: The added benefit of closing all connections on program exit, should the user neglect to do so. In order "to minimize the amount of code added to the basic Unix kernel ", much of the NCP code ran in a swappable user process, running only when needed. 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

3075-514: The assembler that the code will be using the .TTYOUT and .EXIT macros. The .TTYOUT and .EXIT macros are defined in the standard system macro library to expand to the EMT instructions to call the RT-11 monitor to perform the requested functions. If this file is HELLO.MAC , the RT-11 commands to assemble, link and run (with console output shown) are as follows: (The RT-11 command prompt

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3150-465: 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. Early Unix developers were important in bringing the concepts of modularity and reusability into software engineering practice, spawning a "software tools" movement. Over time, the leading developers of Unix (and programs that ran on it) established

3225-435: The basis for implementations on many other platforms. 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 launch of the free software movement in 1983. In 1983, Richard Stallman announced the GNU (short for "GNU's Not Unix") project, an ambitious effort to create a free software Unix-like system—"free" in

3300-492: 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 ). Since the shell and OS commands were "just another program", the user could choose (or even write) their own shell. New commands could be added without changing

3375-636: The concept to the Xerox Palo Alto Research Center (PARC), where it appeared on the Alto , introduced in 1973. From there the idea spread to Niklaus Wirth ’s Lilith in 1980, and the Apple Lisa in 1983, then became ubiquitous. A command-line interface (CLI) is an operating system shell that uses alphanumeric characters typed on a keyboard to provide instructions and data to the operating system, interactively. For example,

3450-479: The core of the Mac OS X operating system, later renamed macOS . Unix-like operating systems are widely used in modern servers , workstations , and mobile devices . 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

3525-546: 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 OpenVMS directories, CP/M 's volumes evolved into MS-DOS 2.0+ subdirectories, and HP's MPE group.account hierarchy and IBM's SSP and OS/400 library systems were folded into broader POSIX file systems. Making

3600-679: The first POSIX standard in 1988. 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 . 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

3675-429: The idea of "using commands somehow like a programming language," and coined the term shell to describe it. In a 1965 document, the shell is defined as "a common procedure called automatically by the supervisor whenever a user types in some message at his console, at a time when he has no other process in active execution under console control. This procedure acts as an interface between console messages and subroutine [in

3750-420: The idea, but adds that "no one can remember" the origin of the final spelling Unix . Dennis Ritchie, Doug McIlroy, and Peter G. Neumann also credit Kernighan. The operating system was originally written in assembly language , but in 1973, Version 4 Unix was rewritten in C . Version 4 Unix, however, still had much PDP-11 specific code, and was not suitable for porting. The first port to another platform

3825-476: 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 and mutually incompatible — systems including DYNIX , HP-UX , SunOS / Solaris , AIX , and Xenix . In the late 1980s, AT&T Unix System Laboratories and Sun Microsystems developed System V Release 4 ( SVR4 ), which

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3900-428: The modular design of the Unix model, sharing components is relatively common: most or all Unix and Unix-like systems include at least some BSD code, while some include GNU utilities in their distributions. Linux and BSD Unix are increasingly filling market needs traditionally served by proprietary Unix operating systems, expanding into new markets such as the consumer desktop , mobile devices and embedded devices . In

3975-443: The more official offerings from the workstation and mainframe manufacturers. In the same interview, he states that he views both Unix and Linux as "the continuation of ideas that were started by Ken and me and many others, many years ago". OpenSolaris was the free software counterpart to Solaris developed by Sun Microsystems , which included a CDDL -licensed kernel and a primarily GNU userland. However, Oracle discontinued

4050-497: The networks and creating the Internet: Commercialization, privatization, broader access leads to the modern Internet: Examples of Internet services: Unix ( / ˈ j uː n ɪ k s / , YOO -niks ; trademarked as UNIX ) is a family of multitasking , multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at

4125-598: The operating system had to be typed by the user, short command names and compact systems for representing program options were common. Short names were sometimes hard for a user to recall, and early systems lacked the storage resources to provide a detailed on-line user instruction guide. A graphical user interface (GUI) provides means for manipulating programs graphically, by allowing for operations such as opening, closing, moving and resizing windows , as well as switching focus between windows. Graphical shells may be included with desktop environments or come separately, even as

4200-475: The operating system should provide a set of simple tools, each of which performs a limited, well-defined function. A unified and inode -based filesystem 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. In the early 1990s, AT&T sold its rights in Unix to Novell , which then sold

4275-503: 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 . The focus on text for representing nearly everything made Unix pipes especially useful and encouraged the development of simple, general tools that could easily be combined to perform more complicated ad hoc tasks. The focus on text and bytes made

4350-599: The project upon their acquisition of Sun, which prompted a group of former Sun employees and members of the OpenSolaris community to fork OpenSolaris into the illumos kernel. As of 2014, illumos remains the only active, open-source System V derivative. In May 1975, RFC 681 described the development of Network Unix by the Center for Advanced Computation at the University of Illinois Urbana-Champaign . The Unix system

4425-591: The related business operations to Santa Cruz Operation (SCO). 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. 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 vendor SCO Group Inc. accused Novell of slander of title . The present owner of

4500-482: The same resource or device simultaneously. To mediate such access, the kernel has special rights, reflected in the distinction of kernel space from user space , the latter being a lower priority realm where most application programs operate. The origins of Unix date back to the mid-1960s when the Massachusetts Institute of Technology , Bell Labs , and General Electric were developing Multics ,

4575-535: The sense that everyone who received a copy would be free to use, study, modify, and redistribute it. The GNU project's own kernel development project, GNU Hurd , had not yet produced a working kernel, but in 1991 Linus Torvalds released the Linux kernel as free software under the GNU General Public License . In addition to their use in the GNU operating system, many GNU packages – such as

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4650-561: The shell consists of an X window manager or a Wayland compositor , respectively, as well as of one or multiple programs providing the functionality to start installed applications, to manage open windows and virtual desktops, and often to support a widget engine. In the case of macOS , Quartz Compositor acts as the windowing system, and the shell consists of the Finder , the Dock , SystemUIServer, and Mission Control . Modern versions of

4725-427: The shell itself. Unix's innovative command-line syntax for creating modular chains of producer-consumer processes ( pipelines ) made a powerful programming paradigm ( coroutines ) widely available. Many later command-line interpreters have been inspired by the Unix shell. A fundamental simplifying assumption of Unix was its focus on newline - delimited text for nearly all file formats. There were no "binary" editors in

4800-654: The software at a nominal fee for educational use, by running on inexpensive hardware, and by being easy to adapt and move to different machines. Unix was originally written in assembly language , but was soon rewritten in C , a high-level programming language . Although this followed the lead of CTSS , Multics and Burroughs MCP , it was Unix that popularized the idea. 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

4875-451: The supervisor]." This system was first implemented by Glenda Schroeder and an unnamed man from General Electric . Multics also introduced the active function , a key concept in all later shells. This is defined as a string... which is replaced by a character string return value before the command line containing it is executed. Active functions are often used... to implement command-language macros. In 1971, Ken Thompson developed

4950-418: 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 , ODF ), and at the application layer of the Internet protocols , e.g., FTP , SMTP , HTTP , SOAP , and SIP . Unix popularized a syntax for regular expressions that found widespread use. The Unix programming interface became

5025-566: The system or a user process. The purpose of such a procedure is to create a medium of exchange into which one could activate any procedure, as if it were called from the inside of another program . Hereafter, for simplification, we shall refer to that procedure as the "SHELL". Louis Pouzin, The SHELL: A Global Tool for Calling and Chaining Procedures in the System In 1964, for the Multics operating system, Louis Pouzin conceived

5100-499: The task to be performed. Early interactive systems provided a simple command-line interpreter as part of the resident monitor . This interpreter might be called by different names, such as COMCON on DEC TOPS-10 systems. The interpreter would execute one of a number of predefined commands, one of which would be to run a user program. Common commands would log the user on and off the system, allocate, free, and manipulate devices and files, and query various pieces of information about

5175-459: The trademark UNIX is The Open Group, an industry standards consortium. Only systems fully compliant with and certified to the Single UNIX Specification qualify as "UNIX" (others are called " Unix-like "). 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

5250-536: Was a port of Version 6, made four years later (1977) at the University of Wollongong for the Interdata 7/32 , followed by a Bell Labs port of Version 7 to the Interdata 8/32 during 1977 and 1978. Bell Labs produced several versions of Unix that are collectively referred to as Research Unix . In 1975, the first source license for UNIX was sold to Donald B. Gillies at the University of Illinois Urbana–Champaign (UIUC) Department of Computer Science. During

5325-431: Was commonly used on minicomputers and mainframes from the 1970s onwards. It distinguished 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 systems are characterized by a modular design that is sometimes called the " Unix philosophy ". According to this philosophy,

5400-402: Was one of the key reasons it emerged as an important teaching and learning tool and has had a broad influence. See § Impact , below. 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 10 MB and arrived on

5475-573: Was released in 1992 and led to the NetBSD and FreeBSD projects. With the 1994 settlement of a lawsuit brought against the University of California and Berkeley Software Design Inc. ( USL v. BSDi ) by Unix System Laboratories , it was clarified that Berkeley had the right to distribute BSD Unix for free if it so desired. Since then, BSD Unix has been developed in several different product branches, including OpenBSD and DragonFly BSD . Because of

5550-516: Was said to "present several interesting capabilities as an ARPANET mini-host". At the time, Unix required a license from Bell Telephone Laboratories that cost US$ 20,000 for non-university institutions, while universities could obtain a license for a nominal fee of $ 150. It was noted that Bell was "open to suggestions" for an ARPANET-wide license. The RFC specifically mentions that Unix "offers powerful local processing facilities in terms of user programs, several compilers , an editor based on QED ,

5625-404: Was subsequently adopted by many commercial Unix vendors. 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. In 2000, Apple released Darwin , also a Unix system, which became

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