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 name, sh. A Unix shell, is a command line shell that provides the traditional User interface for the Unix Operating system and for Unix-like Seventh Edition Unix, also called Version 7 Unix, Version 7 or just V7, was an important early release of the Unix Operating system The Thompson shell was the first Unix shell, introduced in the first version of Unix in 1971, and was written by Ken Thompson. It was developed by Stephen Bourne, of AT&T Bell Laboratories, and was released in 1977 in the Version 7 Unix release distributed to colleges and universities. Steve Bourne is a computer scientist most famous as the author of the Bourne shell (sh which is the foundation for 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 Seventh Edition Unix, also called Version 7 Unix, Version 7 or just V7, was an important early release of the Unix Operating system It remains a popular default shell for Unix accounts. The binary program of the Bourne shell or a compatible program is located at /bin/sh on most Unix systems, and is still the default shell for the root superuser on many current Unix implementations. In Computing, an executable (file causes a computer "to perform indicated tasks according to encoded instructions," as opposed to a file that only contains Unix (officially trademarked as UNIX, sometimes also written as Unix with Small caps) is a computer On many computer Operating systems the superuser, or root, is a special User account used for System administration.

Contents 1 Origins 2 Notable features 3 Descendants 4 Usage 5 Quotes 6 See also 7 References 8 External links

Origins

The shell was designed as a replacement for the original Thompson shell. The Thompson shell was the first Unix shell, introduced in the first version of Unix in 1971, and was written by Ken Thompson.

Among the primary goals were:

• To allow shell scripts to be used as filters. A shell script is a script written for the shell, or Command line interpreter, of an Operating system.
• To provide programmability including control flow and variables. In Computer science control flow (or alternatively flow of control refers to the order in which the individual statements, instructions or Function A variable (ˈvɛərɪəbl is an Attribute of a physical or an abstract System which may change its Value while it is under Observation.
• Control over all input/output file descriptors. In computer programming a file descriptor is an abstract key for accessing a file
• Control over signal handling within scripts. A signal is a limited form of Inter-process communication used in Unix, Unix-like, and other POSIX -compliant operating systems
• No limits on string lengths when interpreting shell scripts.
• Rationalize and generalize string quoting mechanism.
• The environment mechanism. Environment variables are a set of dynamic values that can affect the way running processes will behave on a computer This allowed context to be established at startup and provided a way for shell scripts to pass context to sub scripts (processes) without having to use explicit positional parameters. In computing a process is an instance of a Computer program that is being sequentially executed by a computer system that has the ability to run several computer In Computer programming, a parameter is a variable which takes on the meaning of a corresponding Argument (computer science is same article--> argument

Notable features

Although it is used as an interactive command interpreter, it was always intended as a scripting language. "Scripting" redirects here For other uses see Script. It gained popularity with the publication of The UNIX Programming Environment by Brian W. Kernighan and Rob Pike. The Unix Programming Environment is a textbook written by Brian W Brian Wilson Kernighan (ˈkɛrnɪhæn the 'g' is silent (born 1942 Toronto, Ontario, Canada) is a Computer scientist who worked at Robert C Pike (born 1956 is a Software engineer and Author. He is best known for his work at Bell Labs, where he was a member of the Unix This was the first commercially published book that presented the shell as a programming language in a tutorial form.

The Bourne shell also was the first to feature the convention of using file descriptor 2> for error messages, allowing much greater programmatic control during scripting by keeping error messages separate from data. In computer programming a file descriptor is an abstract key for accessing a file An error message is a message displayed when an unexpected condition occurs usually on a Computer or other device

Other innovations in this shell included:

• Command substitution using back quotes: `command`.
• Here documents using << to embed a block of input text within a script. A here document (also called a here-document or a heredoc) is a way of specifying a String literal in command line shells such as Bash
• "for ~ do ~ done" loops, in particular the use of $* to loop over arguments.
• "case ~ in ~ esac" selection mechanism, primarily intended to assist argument parsing.
• sh provided support for environment variables using keyword parameters and exportable variables.

Over the years, the Bourne shell was enhanced at AT&T. The various variants are thus called like the respective AT&T Unix version it was released with (some important variants being Version7, SystemIII, SVR2, SVR3, SVR4). As the shell was never versioned, the only way to identify it was testing its features.

Stephen Bourne carried into this shell some aspects of the ALGOL 68C compiler that he had been working on at Cambridge University. The ALGOL68C computer programming language compiler was developed for the CHAOS OS for the CAP Capability computer at Cambridge University in The University of Cambridge (often Cambridge University) located in Cambridge, England, is the second-oldest university in the Notably he reused portions of ALGOL 68's "if ~ then ~ elif ~ else ~ fi", "case ~ in ~ out ~ esac" and "for ~ while ~ do ~ od" clauses in the common Unix Bourne shell syntax. Time-line of ALGOL 68 The Algorithmic Language ALGOL 68 Reports Mar Unix (officially trademarked as UNIX, sometimes also written as Unix with Small caps) is a computer Moreover - although the v7 shell is written in C - Bourne took advantage of some macros^[1] to give the C source code an ALGOL 68 flavor. tags please moot on the talk page first! --> In Computing, C is a general-purpose cross-platform block structured A macro (from the Greek 'μάκρο' for long or far in Computer science is a rule or Pattern that specifies how a certain input sequence (often a sequence In Computer science, source code (commonly just source or code) is any sequence of statements or declarations written in some Human-readable These macros co-inspired the IOCCC - International Obfuscated C Code Contest (Co-inspired with the finger command as distributed in Unix version 4.2BSD)^[2]. The International Obfuscated C Code Contest (abbreviated IOCCC) is a Programming contest for the most creatively obfuscated C Code tags please moot on the talk page first! --> In Computing, C is a general-purpose cross-platform block structured In Computer networking, the Name/Finger protocol and the Finger user information protocol are simple Network protocols for the exchange of human-oriented

Descendants

The C shell (csh), derived not from the Bourne shell but the Thompson shell, was distributed with 4. The C shell ( csh) is a Unix shell developed by Bill Joy for the BSD Unix system The Thompson shell was the first Unix shell, introduced in the first version of Unix in 1971, and was written by Ken Thompson. 1BSD, and took advantage of job control features of the BSD kernel. On Operating systems that support executing multiple processes in parallel or in series ( Batch processing) job control refers to the orchestration of multiple Job control is the ability to stop a program interactively and then restart it later. It was for this reason that the C shell gained popularity as a command interpreter. The C shell used a more "C like" syntax for its programming features that was incompatible with the Bourne shell and purportedly an improvement. tags please moot on the talk page first! --> In Computing, C is a general-purpose cross-platform block structured Job control functionality was eventually incorporated into later versions of the Bourne shell, as well as most of its descendants.

The Korn shell (ksh) written much later by David Korn, was a middle road between these two shells, with syntax chiefly drawn from the Bourne shell and job control features drawn from the C shell. The Korn shell ( ksh) is a Unix shell which was developed by David Korn ( AT&T Bell Laboratories) in the early 1980s David Korn is an American Computer programmer, who is probably best known for creating the Korn shell ( ksh) a Command line interface The functionality of the original Korn Shell (known as ksh88 from the year of its introduction) was used as a basis for the POSIX shell standard; a newer version, ksh93, has been open source since 2000 and is used on some Linux distributions; there is also a clone of ksh88 known as pdksh (which is the default shell for all users of OpenBSD). POSIX (ˈpɒzɪks or "Portable Operating System Interface" is the collective name of a family of related standards specified by the IEEE to define The Korn shell ( ksh) is a Unix shell which was developed by David Korn ( AT&T Bell Laboratories) in the early 1980s

rc was created at Bell Labs by Tom Duff as a replacement for sh for Version 10 Unix. rc is the Command line interpreter for Version 10 Unix, Plan 9, and Inferno Operating systems It resembles the Bourne shell Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) is the Research organization Thomas Douglas Selkirk Duff (b December 8, 1952, named for his putative ancestor the fifth Earl of Selkirk) is a Computer programmer. 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 It is the default shell for Plan 9 from Bell Labs. Plan 9 from Bell Labs is a Distributed operating system, primarily used for research It has been ported to UNIX as part of Plan 9 from User Space. Plan 9 from User Space (or plan9port or p9p) is a port of many Plan 9 from Bell Labs libraries and applications to Unix-like

Bash, also known as the Bourne-Again shell, was later developed for the GNU project and takes features from the Bourne shell, csh and ksh. Bash is a Free software Unix shell written for the GNU Project. GNU ( pronounced) is a computer Operating system composed entirely of Free software.

Due to copyright issues surrounding the Bourne Shell as it was used in historic CSRG BSD releases, Kenneth Almquist developed a clone of the Bourne Shell, known by some as the Almquist Shell and available under the BSD license, which is in use today on some BSD descendants and in low-memory situations. The Computer Systems Research Group ( CSRG) was a research group at the University of California Berkeley that was dedicated to enhancing AT&T Unix The Almquist shell (also known as A Shell, ash and sh) was originally Kenneth Almquist's clone of the SVR4 -variant of the Bourne shell BSD licenses represent a family of Permissive free software licences. The Almquist Shell was ported to Linux, and the port renamed the Debian Almquist shell, or dash. D ebian A lmquist sh ell ( dash) is a POSIX -compliant Unix shell, much smaller than Bash. This shell provides much faster execution of standard sh scripts with a smaller memory footprint than its more common counterpart, bash. Its use tends to expose bashisms - bash-centric assumptions made in scripts meant to run on sh. Bash is a Free software Unix shell written for the GNU Project.

Usage

The Bourne shell was once standard on all branded Unix systems, although historically BSD based systems had many scripts written in csh. Unix (officially trademarked as UNIX, sometimes also written as Unix with Small caps) is a computer The C shell ( csh) is a Unix shell developed by Bill Joy for the BSD Unix system Bourne shell scripts can typically be run with bash or dash on Linux or other Unix-like systems. Bash is a Free software Unix shell written for the GNU Project. D ebian A lmquist sh ell ( dash) is a POSIX -compliant Unix shell, much smaller than Bash. Linux (commonly pronounced ˈlɪnəks 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

After Sun released their OpenSolaris variant of the Bourne shell as Open Source, a port of this shell for free Unix flavours (geared for legacy portability and historic interest) has been made available by the Heirloom Project. 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 The Heirloom Project is a collection of traditional Unix utilities [1] The Solaris/SVR4 version of the Bourne Shell does not have the same ALGOL68ized source code as the original. Time-line of ALGOL 68 The Algorithmic Language ALGOL 68 Reports Mar

Quotes

"Nobody really knows what the Bourne shell's grammar is. Even examination of the source code is little help. "

– Tom Duff ^[3]

See also

• Comparison of computer shells
• Bash
• rc

References

External links

• UNIX Shell Script Tutorials & Reference
• UNIX/Linux Bourne/Bash Shell Scripting Tutorial
• The individual members of "The Traditional Bourne Shell Family"
• Actual C source code for the Bourne shell using mac.h macros
• Original Bourne Shell documentation from 1978
• A port of the "heirloom" SVR4 Bourne shell from OpenSolaris to other Unix-like systems

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