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AWK (programming Language)
AWK () is a domain-specific language designed for text processing and typically used as a data extraction and reporting tool. Like sed and grep, it is a filter (software), filter, and it is a standard feature of most Unix-like, Unix-like operating systems. The AWK language is a data-driven programming, data-driven scripting language consisting of a set of actions to be taken against Stream (computing), streams of textual data – either run directly on files or used as part of a pipeline (Unix), pipeline – for purposes of extracting or transforming text, such as producing formatted reports. The language extensively uses the string (computer science), string datatype, associative arrays (that is, arrays indexed by key strings), and regular expressions. While AWK has a limited intended Domain (software engineering), application domain and was especially designed to support one-liner programs, the language is Turing-complete, and even the early Bell Labs users of AWK often wrote w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scripting Language
In computing, a script is a relatively short and simple set of instructions that typically automation, automate an otherwise manual process. The act of writing a script is called scripting. A scripting language or script language is a programming language that is used for scripting. Originally, scripting was limited to automating an operating system shell and languages were relatively simple. Today, scripting is more pervasive and some languages include modern features that allow them to be used for Application software, application development as well as scripting. Overview A scripting language can be a general purpose language or a domain-specific language for a particular environment. When embedded in an application, it may be called an extension language. A scripting language is sometimes referred to as very high-level programming language if it operates at a high level of abstraction, or as a control language, particularly for job control languages on mainframes. The te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stream (computing)
In computer science, a stream is a sequence of potentially unlimited data elements made available over time. A stream can be thought of as items on a conveyor belt being processed one at a time rather than in large batches. Streams are processed differently from batch data. Normal functions cannot operate on streams as a whole because they have potentially unlimited data. Formally, streams are '' codata'' (potentially unlimited), not data (which is finite). Functions that operate on a stream producing another stream are known as filters and can be connected in pipelines in a manner analogous to function composition. Filters may operate on one item of a stream at a time or may base an item of output on multiple items of input such as a moving average. Examples The term "stream" is used in a number of similar ways: * "Stream editing", as with sed, awk, and perl. Stream editing processes a file or files, in-place, without having to load the file(s) into a user interface. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plan 9 From Bell Labs
Plan 9 from Bell Labs is a distributed operating system which originated from the Computing Science Research Center (CSRC) at Bell Labs in the mid-1980s and built on UNIX concepts first developed there in the late 1960s. Since 2000, Plan 9 has been free and open-source. The final official release was in early 2015. Under Plan 9, UNIX's '' everything is a file'' metaphor is extended via a pervasive network-centric filesystem, and the cursor-addressed, terminal-based I/O at the heart of UNIX-like operating systems is replaced by a windowing system and graphical user interface without cursor addressing, although rc, the Plan 9 shell, is text-based. The name ''Plan 9 from Bell Labs'' is a reference to the Ed Wood 1957 cult science fiction Z-movie '' Plan 9 from Outer Space''. The system continues to be used and developed by operating system researchers and hobbyists. History Plan 9 from Bell Labs was originally developed, starting in the late 1980s, by members of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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, 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). The early versions of Unix—which are retrospectively referred to as " Research Unix"—ran on computers such as the PDP-11 and VAX; Unix 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 (in 1973), which allows U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 language and is the '' de facto'' standard for the language, written by its inventors. W. Richard Stevens, author of several UNIX books including '' Advanced Programming in the Unix Environment'', cites the book as one of his favorite technical books. The book is translated to several languages and is cited by many technical papers in the ACM journals. According to the book's frontmatter the book was typeset "using an Autologic APS-5 phototypesetter and a DEC VAX 8550 running the 9th Edition of the UNIX operating system". In September 2023, the second edition was published by Addison-Wesley Addison–Wesley is an American publisher of textbooks and computer literature. It is an imprint of Pearson plc, a global publishing and education c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Egrep
grep is a command-line utility for searching plaintext datasets for lines that match a regular expression. Its name comes from the ed command g/re/p (global regular expression search and print), which has the same effect. grep was originally developed for the Unix operating system, but later became available for all Unix-like systems and some others such as OS-9. History Before it was named, grep was a private utility written by Ken Thompson to search files for certain patterns. Doug McIlroy, unaware of its existence, asked Thompson to write such a program. Responding that he would think about such a utility overnight, Thompson actually corrected bugs and made improvements for about an hour on his own program called "s" (short for "search"). The next day he presented the program to McIlroy, who said it was exactly what he wanted. Thompson's account may explain the belief that grep was written overnight. Thompson wrote the first version in PDP-11 assembly language to help Le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 company operates several laboratories in the United States and around the world. As a former subsidiary of the American Telephone and Telegraph Company (AT&T), Bell Labs and its researchers have been credited with the development of radio astronomy, the transistor, the laser, the photovoltaic cell, the charge-coupled device (CCD), information theory, the Unix operating system, and the programming languages B (programming language), B, C (programming language), C, C++, S (programming language), S, SNOBOL, AWK, AMPL, and others, throughout the 20th century. Eleven Nobel Prizes and five Turing Awards have been awarded for work completed at Bell Laboratories. Bell Labs had its origin in the complex corporate organization of the Bell System telepho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turing-complete
In computability theory, a system of data-manipulation rules (such as a model of computation, a computer's instruction set, a programming language, or a cellular automaton) is said to be Turing-complete or computationally universal if it can be used to simulate any Turing machine (devised by English mathematician and computer scientist Alan Turing). This means that this system is able to recognize or decode other data-manipulation rule sets. Turing completeness is used as a way to express the power of such a data-manipulation rule set. Virtually all programming languages today are Turing-complete. A related concept is that of Turing equivalence two computers P and Q are called equivalent if P can simulate Q and Q can simulate P. The Church–Turing thesis conjectures that any function whose values can be computed by an algorithm can be computed by a Turing machine, and therefore that if any real-world computer can simulate a Turing machine, it is Turing equivalent to a Turing ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
One-liner Program
In computer programming, a one-liner program originally was textual input to the command line of an operating system shell that performed some function in just one line of input. In the present day, a one-liner can be * an expression written in the language of the shell; * the invocation of an interpreter together with program source for the interpreter to run; * the invocation of a compiler together with source to compile and instructions for executing the compiled program. Certain dynamic languages for scripting, such as AWK, sed, and Perl, have traditionally been adept at expressing one-liners. Shell interpreters such as Unix shells or Windows PowerShell allow for the construction of powerful one-liners. The use of the phrase ''one-liner'' has been widened to also include program-source for any language that does something useful in one line. History The concept of a one-liner program has been known since the 1960s with the release of the APL programming language. Wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Domain (software Engineering)
In software engineering, domain is the targeted subject area of a computer program. Formally it represents the target subject of a specific programming project, whether narrowly or broadly defined. For example, for a particular programming project that has as a goal of the creation of a program for a particular hospital, that hospital would be the domain. Or, the project can be expanded in scope to include hospitals as its domain. In a computer programming design, one defines a domain by delineating a set of common requirements, terminology, and functionality for any software program constructed to solve a problem in the area of computer programming, known as '' domain engineering''. The word "domain" is also taken as a synonym of ''application domain''. Domain in the realm of software engineering commonly refers to the subject area on which the application is intended to apply. In other words, during application development, the domain is the "sphere of knowledge and activity ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Regular Expression
A regular expression (shortened as regex or regexp), sometimes referred to as rational expression, is a sequence of characters that specifies a match pattern in text. Usually such patterns are used by string-searching algorithms for "find" or "find and replace" operations on strings, or for input validation. Regular expression techniques are developed in theoretical computer science and formal language theory. The concept of regular expressions began in the 1950s, when the American mathematician Stephen Cole Kleene formalized the concept of a regular language. They came into common use with Unix text-processing utilities. Different syntaxes for writing regular expressions have existed since the 1980s, one being the POSIX standard and another, widely used, being the Perl syntax. Regular expressions are used in search engines, in search and replace dialogs of word processors and text editors, in text processing utilities such as sed and AWK, and in lexical analysis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Associative Array
In computer science, an associative array, key-value store, map, symbol table, or dictionary is an abstract data type that stores a collection of (key, value) pairs, such that each possible key appears at most once in the collection. In mathematical terms, an associative array is a function with ''finite'' domain. It supports 'lookup', 'remove', and 'insert' operations. The dictionary problem is the classic problem of designing efficient data structures that implement associative arrays. The two major solutions to the dictionary problem are hash tables and search trees..Dietzfelbinger, M., Karlin, A., Mehlhorn, K., Meyer auf der Heide, F., Rohnert, H., and Tarjan, R. E. 1994"Dynamic Perfect Hashing: Upper and Lower Bounds". SIAM J. Comput. 23, 4 (Aug. 1994), 738-761. http://portal.acm.org/citation.cfm?id=182370 It is sometimes also possible to solve the problem using directly addressed arrays, binary search trees, or other more specialized structures. Many programmin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
