Brian Wilson Kernighan (; born January 30, 1942) is a Canadian

computer scientist A computer scientist is a scientist who specializes in the academic study of computer science. Computer scientists typically work on the theoretical side of computation. Although computer scientists can also focus their work and research on ...

. He worked at

Bell Labs Nokia Bell Labs, commonly referred to as ''Bell Labs'', is an American industrial research and development company owned by Finnish technology company Nokia. With headquarters located in Murray Hill, New Jersey, Murray Hill, New Jersey, the compa ...

and contributed to the development of

Unix Unix (, ; 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 the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

alongside Unix creators

Ken Thompson Kenneth Lane Thompson (born February 4, 1943) is an American pioneer of computer science. Thompson worked at Bell Labs for most of his career where he designed and implemented the original Unix operating system. He also invented the B (programmi ...

and

Dennis Ritchie Dennis MacAlistair Ritchie (September 9, 1941 – October 12, 2011) was an American computer scientist. He created the C programming language and the Unix operating system and B language with long-time colleague Ken Thompson. Ritchie and Thomp ...

. Kernighan's name became widely known through co-authorship of the first book on the

C programming language C (''pronounced'' '' – like the letter c'') is a general-purpose programming language. It was created in the 1970s by Dennis Ritchie and remains very widely used and influential. By design, C's features cleanly reflect the capabilities of ...

(''

The C Programming Language ''The C Programming Language'' (sometimes termed ''K&R'', after its authors' initials) is a computer programming book written by Brian Kernighan and Dennis Ritchie, the latter of whom originally designed and implemented the C programming langu ...

'') with Dennis Ritchie. Kernighan affirmed that he had no part in the design of the C language ("it's entirely Dennis Ritchie's work"). Kernighan authored many Unix programs, including ditroff. He is coauthor of the AWK and

AMPL AMPL (A Mathematical Programming Language) is an algebraic modeling language to describe and solve high-complexity problems for large-scale mathematical computing (e.g. large-scale optimization and scheduling-type problems). It was developed ...

programming language A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually def ...

s. The "K" of

K&R C C (''pronounced'' '' – like the letter c'') is a general-purpose programming language. It was created in the 1970s by Dennis Ritchie and remains very widely used and influential. By design, C's features cleanly reflect the capabilities of ...

and of AWK both stand for "Kernighan". In collaboration with

Shen Lin __NOTOC__ Shen may refer to: * Shen (Chinese religion) (神), a central word in Chinese philosophy, religion, and traditional Chinese medicine; term for god or spirit * Shen (clam-monster) (蜃), a shapeshifting Chinese dragon believed to create m ...

he devised well-known

heuristic A heuristic or heuristic technique (''problem solving'', '' mental shortcut'', ''rule of thumb'') is any approach to problem solving that employs a pragmatic method that is not fully optimized, perfected, or rationalized, but is nevertheless ...

s for two

NP-complete In computational complexity theory, NP-complete problems are the hardest of the problems to which ''solutions'' can be verified ''quickly''. Somewhat more precisely, a problem is NP-complete when: # It is a decision problem, meaning that for any ...

optimization problems:

graph partition In mathematics, a graph partition is the reduction of a Graph (discrete mathematics), graph to a smaller graph by partition of a set, partitioning its set of nodes into mutually exclusive groups. Edges of the original graph that cross between the g ...

ing and the

travelling salesman problem In the Computational complexity theory, theory of computational complexity, the travelling salesman problem (TSP) asks the following question: "Given a list of cities and the distances between each pair of cities, what is the shortest possible ...

. In a display of authorial equity, the former is usually called the

Kernighan–Lin algorithm The Kernighan–Lin algorithm is a heuristic algorithm for finding partitions of graphs. The algorithm has important practical application in the layout of digital circuits and components in electronic design automation of VLSI. Description The ...

, while the latter is known as the

Lin–Kernighan heuristic In combinatorial optimization, Lin–Kernighan is one of the best heuristics for solving the symmetric travelling salesman problem. It belongs to the class of local search algorithms, which take a tour (Hamiltonian cycle) as part of the input ...

. Kernighan has been a professor of computer science at

Princeton University Princeton University is a private university, private Ivy League research university in Princeton, New Jersey, United States. Founded in 1746 in Elizabeth, New Jersey, Elizabeth as the College of New Jersey, Princeton is the List of Colonial ...

since 2000 and is the director of undergraduate studies in the department of computer science. In 2015, he co-authored the book ''The Go Programming Language''.

Early life and education

Kernighan was born in

Toronto Toronto ( , locally pronounced or ) is the List of the largest municipalities in Canada by population, most populous city in Canada. It is the capital city of the Provinces and territories of Canada, Canadian province of Ontario. With a p ...

. He attended the

University of Toronto The University of Toronto (UToronto or U of T) is a public university, public research university whose main campus is located on the grounds that surround Queen's Park (Toronto), Queen's Park in Toronto, Ontario, Canada. It was founded by ...

between 1960 and 1964, earning his

bachelor's degree A bachelor's degree (from Medieval Latin ''baccalaureus'') or baccalaureate (from Modern Latin ''baccalaureatus'') is an undergraduate degree awarded by colleges and universities upon completion of a course of study lasting three to six years ...

engineering physics Engineering physics (EP), sometimes engineering science, is the field of study combining pure science disciplines (such as physics, mathematics, chemistry or biology) and engineering disciplines (computer, nuclear, electrical, aerospace, medic ...

. He received his Ph.D. in

electrical engineering Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems that use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the l ...

from Princeton University in 1969, completing a doctoral dissertation titled "Some graph partitioning problems related to program segmentation" under the supervision of Peter G. Weiner.

Career and research

Kernighan has held a professorship in the department of computer science at Princeton since 2000. Each fall he teaches a course called "Computers in Our World", which introduces the fundamentals of computing to non-majors. Kernighan was the software editor for Prentice Hall International. His "Software Tools" series spread the essence of "C/Unix thinking" with makeovers for

BASIC Basic or BASIC may refer to: Science and technology * BASIC, a computer programming language * Basic (chemistry), having the properties of a base * Basic access authentication, in HTTP Entertainment * Basic (film), ''Basic'' (film), a 2003 film ...

, FORTRAN, and Pascal, and most notably his "

Ratfor Ratfor (short for ''Rational Fortran'') is a programming language implemented as a preprocessor for Fortran#FORTRAN 66, Fortran 66. It provides Structured programming, modern control structures, unavailable in Fortran 66, to replace GOTOs and sta ...

" (rational FORTRAN) was put in the

public domain The public domain (PD) consists of all the creative work to which no Exclusive exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly Waiver, waived, or may be inapplicable. Because no one holds ...

. He has said that if stranded on an island with only one programming language it would have to be C. Kernighan coined the term "Unix" and helped popularize Thompson's

Unix philosophy The Unix philosophy, originated by Ken Thompson, is a set of cultural norms and philosophical approaches to Minimalism (computing), minimalist, Modularity (programming), modular software development. It is based on the experience of leading devel ...

. Kernighan is also known for coining the expression "What You See Is All You Get" (WYSIAYG), which is a sarcastic variant of the original "What You See Is What You Get" (

WYSIWYG In computing, WYSIWYG ( ), an acronym for what you see is what you get, refers to software that allows content to be edited in a form that resembles its appearance when printed or displayed as a finished product, such as a printed document, web ...

). Kernighan's term is used to indicate that WYSIWYG systems might throw away information in a document that could be useful in other contexts. In 1972, Kernighan described memory management in strings using "hello" and "world", in the

B programming language B is a programming language developed at Bell Labs circa 1969 by Ken Thompson and Dennis Ritchie. B was derived from BCPL, and its name may possibly be a contraction of BCPL. Thompson's coworker Dennis Ritchie speculated that the name might be ...

, which became the iconic example we know today. Kernighan's original 1978 implementation of was sold at The Algorithm Auction, the world's first auction of

computer algorithm In mathematics and computer science, an algorithm () is a finite sequence of Rigour#Mathematics, mathematically rigorous instructions, typically used to solve a class of specific Computational problem, problems or to perform a computation. Algo ...

s. In 1996, Kernighan taught CS50 which is the

Harvard University Harvard University is a Private university, private Ivy League research university in Cambridge, Massachusetts, United States. Founded in 1636 and named for its first benefactor, the History of the Puritans in North America, Puritan clergyma ...

introductory course in computer science. Kernighan was an influence on David J. Malan who subsequently taught the course and scaled it up to run at multiple universities and in multiple digital formats. Kernighan was elected a member of the

National Academy of Engineering The National Academy of Engineering (NAE) is an American Nonprofit organization, nonprofit, NGO, non-governmental organization. It is part of the National Academies of Sciences, Engineering, and Medicine (NASEM), along with the National Academ ...

in 2002 for contributions to software and to programming languages. He was also elected a member of the

American Academy of Arts and Sciences The American Academy of Arts and Sciences (The Academy) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, and other ...

in 2019. In 2022, Kernighan stated that he was actively working on improvements to the AWK programming language, which he took part in creating in 1977.

Books and reports

* '' The Elements of Programming Style'', with

P. J. Plauger Phillip James (P.J. or Bill) Plauger (; born January 13, 1944, Petersburg, West Virginia) is an author, entrepreneur and computer programmer. He has written and co-written articles and books about programming style, software tools, and the C pr ...

* ''Software Tools'', a book and set of tools for

, co-created in part with P. J. Plauger * ''Software Tools in Pascal'', a book and set of tools for Pascal, with P. J. Plauger * ''

'', with C creator Dennis Ritchie, the first book on C * ''

The Practice of Programming ''The Practice of Programming'' () by Brian W. Kernighan and Rob Pike is a 1999 book about computer programming and software engineering, published by Addison-Wesley. According to the preface, the book is about "topics like testing, debuggin ...

'', with

Rob Pike Robert Pike (born 1956) is a Canadian programmer and author. He is best known for his work on the Go programming language while working at Google and the Plan 9 operating system while working at Bell Labs, where he was a member of the Unix t ...

* '' The Unix Programming Environment'', a tutorial book, with Rob Pike
"Why Pascal is Not My Favorite Programming Language"
a popular criticism of

Niklaus Wirth Niklaus Emil Wirth ( IPA: ) (15 February 1934 – 1 January 2024) was a Swiss computer scientist. He designed several programming languages, including Pascal, and pioneered several classic topics in software engineering. In 1984, he won the Tu ...

's Pascal. Some parts of the criticism are obsolete due to ISO 7185 (Programming Languages - Pascal); the criticism was written before ISO 7185 was created. (AT&T Computing Science Technical Report #100) * ''UNIX: A History and a Memoir'', a historical account of the development of

from the perspective of his role at

Programs

* 1972: The first documented

"Hello, world!" program A "Hello, World!" program is usually a simple computer program that emits (or displays) to the screen (often the Console application, console) a message similar to "Hello, World!". A small piece of code in most general-purpose programming languag ...

, in Kernighan'
"A Tutorial Introduction to the Language B"
* 1973: ditroff, or "device independent

troff troff (), short for "typesetter roff", is the major component of a document processing system developed by Bell Labs for the Unix operating system. troff and the related nroff were both developed from the original roff (software), roff. Whil ...

", which allowed troff to be used with any device * 1974: The eqn typesetting language for troff, with

Lorinda Cherry Lorinda Cherry ( Landgraf; November 18, 1944 – February 11, 2022) was an American computer scientist and programmer. Much of her career was spent at Bell Labs, where she was for many years a member of the original Unix Lab. Cherry developed se ...

* 1976:

* 1977: The m4 macro processing language, with Dennis Ritchie * 1977: The AWK programming language, with

Alfred Aho Alfred Vaino Aho (born August 9, 1941) is a Canadian computer scientist best known for his work on programming languages, compilers, and related algorithms, and his textbooks on the art and science of computer programming. Aho was elected into ...

and Peter J. Weinberger, and its book ''

The AWK Programming Language ''The AWK Programming Language'' is a well-known 1988 book written by Alfred V. Aho, Brian W. Kernighan, and Peter J. Weinberger and published by Addison-Wesley, often referred to as the gray book. The book describes the AWK programming languag ...

'' * 1985: The

programming language * 1988: The

pic PIC or pic may refer to: Places * Penbay International Circuit, or PIC, a motor track circuit in Pingtung County, Taiwan * Pic River, in Ontario, Canada * Picayune (Amtrak station) (Amtrak station code PIC), Mississippi, United States * Pic, a ...

typesetting language for troff

Publications

* '' The Elements of Programming Style'' (1974, 1978) with P. J. Plauger * ''Software Tools'' (1976) with P. J. Plauger * ''

'' (1978, 1988) with Dennis M. Ritchie * ''Software Tools in Pascal'' (1981) with P. J. Plauger * ''The Unix Programming Environment'' (1984) with Rob Pike * ''

'' (1988, 2023) with Alfred Aho and Peter J. Weinberger * ''

'' (1999) with Rob Pike * ''AMPL: A Modeling Language for Mathematical Programming, 2nd ed.'' (2003) with

Robert Fourer Robert Fourer (born September 2, 1950) is a scientist working in the area of operations research and management science. He is currently President of AMPL Optimization, Inc and is Professor Emeritus of Industrial Engineering and Management Science ...

and David Gay * ''D is for Digital: What a well-informed person should know about computers and communications'' (2011) * ''The Go Programming Language'' (2015) with Alan Donovan * ''Understanding the Digital World: What You Need to Know about Computers, the Internet, Privacy, and Security'' (2017) * ''Millions, Billions, Zillions: Defending Yourself in a World of Too Many Numbers'' (2018) * ''UNIX: A History and a Memoir'' (2019)UNIX: A History and a Memoir

References

External links

Brian Kernighan's home page at Bell LabsLex Fridman Podcast #109: Brian Kernighan - UNIX, C, AWK, AMPL, and Go Programming
nbsp;— By Brian Kernighan, AT&T Bell Labs, 2 April 1981
"Leap In and Try Things" — Interview with Brian Kernighan
nbsp;— on "Harmony at Work Blog", October 2009.

nbsp;— By Mihai Budiu, for ''PC Report Romania'', August 2000 * – Interview by

nbsp;— TechNetCast At Bell Labs: Dennis Ritchie and Brian Kernighan (1999-05-14)
Video (Princeton University, September 7, 2003)
nbsp;— "Assembly for the Class of 2007: 'D is for Digital and Why It Matters'"
A Descent into Limbo
by Brian Kernighan

*
Video interview with Brian Kernighan for Princeton Startup TV
(2012-03-20)
The Setup, Brian Kernighan

A collection of Kernighan's opinion columns from

The Daily Princetonian ''The Daily Princetonian'', originally known as ''The Princetonian'' and nicknamed the Prince, is the independent daily student newspaper of Princeton University. The newspaper is owned by The Daily Princetonian Publishing Co. and boasts a cir ...

, 2006–2013. {{DEFAULTSORT:Kernighan, Brian 1942 births Living people Canadian computer scientists Canadian computer programmers Computer programmers Inferno (operating system) people Canadian people of Irish descent Writers from Toronto Plan 9 people Princeton University School of Engineering and Applied Science alumni Princeton University faculty Programming language designers Scientists at Bell Labs Canadian technology writers University of Toronto alumni Unix people C (programming language) Members of the United States National Academy of Engineering Berkman Fellows Scientists from Toronto