Note: "broken bar" and the glyph "¦" redirect here.

The symbol (|) has various names that refer to differing, yet sometimes related semantics: One of the more popular names is the Sheffer stroke, though often referred to as a pipe (by the Unix community) and Vertical bar, verti-bar, vertical line or divider line by others. NAND Logic gate The Sheffer stroke, written | or ↑, denotes a logical operation that is equivalent to the negation of the conjunction operation, expressed in ordinary language as not both. It is also called the alternative denial, since it says in effect that at least one of its operands is false. ...

Broken bar (¦) is a separate character.

The typical keyboard layout used in the United Kingdom features separate keys for vertical bar and broken bar, however most UK keyboard drivers today map both keys onto the vertical bar, as broken bar has hardly any practical application. Keyboards in other countries do not make this distinction, and there, the vertical bar character is often depicted as a broken bar, to distinguish it from the "I" (uppercase "i") character. A standard Hebrew keyboard showing both Hebrew and English (QWERTY) letters. ...

Etymology

The name pipe for the character "|" was a natural consequence of its usage in Unix shells, where it is used to notate the usage of the Unix pipeline construct. A pipeline of three programs run on a text terminal In Unix-like computer operating systems, a pipeline is the original software pipeline: a set of processes chained by their standard streams, so that the output of each process (stdout) feeds directly as input (stdin) of the next one. ...

Usage

Mathematics

The vertical bar is used as a mathematical symbol in The following table lists many specialized symbols commonly used in mathematics. ...

• absolute value: | x | , read "the absolute value of x".
• norms: , read "the norm of x sub one, x sub two"; though Unicode also provides a special double vertical line symbol U+2016: ‖x‖
• set definition: {x | x < 2}, read "the set of x such that x is less than two". Often sets are written with a colon ':' rather than a vertical bar.
• conditional probability: P(X | Y), read "the probability of X given Y".
• divisibility: a | b, read "a divides b".
• the Sheffer stroke in logic: a | b, read "a nand b".
• evaluate: a + 3 | a = 4, read "a plus 3 evaluated for when a equals 4", or 4 + 3 = 7.

In mathematics, the absolute value (or modulus[1]) of a real number is its numerical value without regard to its sign. ... For other uses, see X (disambiguation). ... In linear algebra, functional analysis and related areas of mathematics, a norm is a function which assigns a positive length or size to all vectors in a vector space, other than the zero vector. ... A subscript is a number, figure, or indicator that appears below the normal line of type, typically used in a formula, mathematical expression, or description of a chemical compound. ... In mathematics, a set can be thought of as any collection of distinct objects considered as a whole. ... For the socioeconomic meaning, see social inequality. ... 2 (two) is the natural number following 1 and preceding 3. ... This article is about colons in punctuation. ... This article defines some terms which characterize probability distributions of two or more variables. ... Probability is the likelihood that something is the case or will happen. ... In mathematics, a divisor of an integer n, also called a factor of n, is an integer which evenly divides n without leaving a remainder. ... NAND Logic gate The Sheffer stroke, written | or ↑, denotes a logical operation that is equivalent to the negation of the conjunction operation, expressed in ordinary language as not both. It is also called the alternative denial, since it says in effect that at least one of its operands is false. ... Logic (from Classical Greek λόγος logos; meaning word, thought, idea, argument, account, reason, or principle) is the study of the principles and criteria of valid inference and demonstration. ... An interpreter is a computer program that executes other programs. ...

Backus-Naur form

In Backus-Naur form the expression consists of sequences of symbols and/or sequences separated by '|', indicating a choice, the whole being a possible substitution for the symbol on the left. The Backus-Naur form (BNF) (also known as Backus normal form) is a metasyntax used to express context-free grammars: that is, a formal way to describe formal languages. ...

<personal-name> ::= <name> | <initial>

Computing

Unix

A pipe is an inter-process communication mechanism originating in Unix which allows the output (standard out and, optionally, standard error) of one process to be used as input (standard in) to another. In this way, a series of commands can be "piped" together. This provides skilled practitioners the ability to quickly perform complex processing on the command line or as part of a UNIX shell script ("batch file"). In most Unix shells (command interpreters), this is represented by the vertical bar character. In UNIX and other Unix-like operating systems, a pipeline is a set of processes chained by their standard streams, so that the output of each process (stdout) feeds directly as input (stdin) of the next one. ... Inter-Process Communication (IPC) is a set of techniques for the exchange of data between two or more threads in one or more processes. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... Screenshot of a sample Bash session, taken on Gentoo Linux. ...

e.g. Piped UNIX commands: egrep -i 'blair' filename.log | more

Traditionally, the piping capability in UNIX is provided by the "fork and exec" feature of UNIX operating systems. The UNIX shell forks off a copy of itself for each command, connecting the input of each to the output of the next. When processing large amounts of data, all processes in the pipeline will typically be active at the same time (within the limits of the hardware used). Using the UNIX pipe mechanism, a user is able to quickly and easily build a custom program composed of a (theoretically) unlimited number of small, specialized programs.

DOS/Windows

This feature is found in later versions of Microsoft DOS (and hence Microsoft Windows) as well, however, the smaller DOS command set, the limited command functionality and crude shell capabilities means that piping is less useful in the more visual Microsoft Windows environment. However Cygwin and MKS toolkit provide complete UNIX tool sets for the Windows environment, including UNIX shells (BASH & Korn shell respectively) which provide the same powerful piping capabilities as UNIX.

e.g. Piped DOS command: type *.txt | more

The role of the character as a DOS operator can result in problems for command line applications such as the SQL Server BCP utility (short for "Bulk Copy Program"), where the user may wish to pass the "|" character to the application as a literal. (For example, when trying to bulk copy a file that uses the | character as a field separator.) In these cases, the ^ character can be used to escape the pipe. For example:

bcp tblImport in ImportFile.txt -c -t^|

Regular expression

In regular expression syntax, the pipe indicates alternation (i.e. logical OR). For example: the Unix command grep -E 'foo|bar' matches lines containing 'foo' or 'bar'. In computing, a regular expression is a string that is used to describe or match a set of strings, according to certain syntax rules. ... grep is a command line utility that was originally written for use with the Unix operating system. ...

Disjunction

In many programming languages, it is used to designate the logic operation or, either bitwise or or logical or. OR logic gate. ... In computer programming, a bitwise operation operates on one or two bit patterns or binary numerals at the level of their individual bits. ... In computer science, the Boolean datatype, sometimes called the logical datatype, is a primitive datatype having two values: one and zero (which are equivalent to true and false). ...

Specifically, in C and other languages following C syntax conventions, such as C++, Perl, Java and C#, (a | b) denotes a bitwise or; whilst a double vertical bar (a || b) denotes a (short-circuited) logical or. C is a general-purpose, block structured, procedural, imperative computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system. ... C++ (pronounced see plus plus, IPA: ) is a general-purpose programming language with high-level and low-level capabilities. ... Wikibooks has a book on the topic of Perl Programming Perl is a dynamic programming language created by Larry Wall and first released in 1987. ... Java language redirects here. ... The title given to this article is incorrect due to technical limitations. ... In computer programming, a bitwise operation operates on one or two bit patterns or binary numerals at the level of their individual bits. ... In computer programming, lazy evaluation is a concept that attempts to minimize the work the computer has to do. ... OR logic gate. ...

Concatenation

In PL/I and certain dialects of SQL, the operator "||" denotes string concatenation. PL/I (Programming Language One, pronounced pee el one) is an imperative computer programming language designed for scientific, engineering, and business applications. ... A dialect of a programming language is a (relatively small) variation or extension of the language that does not change its intrinsic nature. ... SQL (IPA: or ), commonly expanded as Structured Query Language, is a computer language designed for the retrieval and management of data in relational database management systems, database schema creation and modification, and database object access control management. ... In computer programming and formal language theory, (and other branches of mathematics), a string is an ordered sequence of symbols. ... Concatenation is a standard operation in computer programming languages (a subset of formal language theory). ...

Delimiter

Although not as common as commas or tabs, the vertical bar can be used as a delimiter in a flat file. An example of a pipe-delimited standard data format is LEDES 1998B. Delimiters are marks which are used to seperate subfields of data. ... The term flat file can refer to a flat-file database, or to a simple type of file system for computers. ... The Legal Electronic Data Exchange Standard is a set of two file format specifications intended to standardize bill/invoice data transmitted electronically (e-billed) from a law firm to a corporate client. ...

Concurrency operator

In calculi of communicating processes (like Pi-calculus), the vertical bar is used to indicate that processes execute in parallel. In theoretical computer science, the &#960;-calculus is a notation originally developed by Robin Milner, Joachim Parrow and David Walker to model concurrency (just as the &#955;-calculus is a simple model of sequential programming languages). ...

Phonetics and orthography

In the Khoisan languages and International Phonetic Alphabet, the pipe is used to write the dental click (ǀ). The double vertical line is used to write the lateral alveolar click (ǁ). The Khoisan languages (also Khoesaan languages) are the indigenous languages of southern and eastern Africa; in southern Africa their speakers are the Khoi and Bushmen (Saan). ... Articles with similar titles include the NATO phonetic alphabet, which has also informally been called the “International Phonetic Alphabet”. For information on how to read IPA transcriptions of English words, see IPA chart for English. ... Tsk redirects here. ... The lateral alveolar click is a type of consonantal sound, used in some spoken languages. ...

Encoding

Despite the vertical bar being an accessible keystroke on typical North American and UK keyboards, there are cases where Web designers, Wiki editors, computer programmers, and others need to encode the vertical bar — usually because the vertical bar is a special symbol in their source code and yet a literal vertical bar needs to be displayed to the end user.

Set forth in 1963, American Standard Code for Information Interchange (ASCII-1963), one of the first widely used character maps only had 69 display ("printable") characters; and A–Z, and 0–9 accounts for 36 of those characters. Vertical bar ("|") is the ASCII-1963 character at position 124 (decimal). Broken bar ("¦") is not part of the ASCII character set (any version), but a separate character that appeared (along with vertical bar) first in the EBCDIC family of character sets, and was copied from there into ISO 8859-1 and Unicode. The typical computer keyboard used in the United Kingdom features separate keys for "vertical bar" and "broken bar", however most UK keyboard drivers today map both keys onto the ASCII character "vertical bar", as "broken bar" has hardly any practical application. For other uses, see 1963 (disambiguation). ...

In common character maps

Unicode

hexadecimal (base-16): 007C The Unicode Standard, Version 5. ...

UTF-8

hexadecimal (base-16): 7C UTF-8 (8-bit UCS/Unicode Transformation Format) is a variable-length character encoding for Unicode. ...

ASCII

decimal (base-10): 124, or hexadecimal (base-16): 7C Image:ASCII fullsvg There are 95 printable ASCII characters, numbered 32 to 126. ...

ISO/IEC 8859-1

hexadecimal (base-16): 7C ISO 8859-1, more formally cited as ISO/IEC 8859-1 or less formally as Latin-1, is part 1 of ISO/IEC 8859, a standard character encoding of the Latin alphabet. ...

Shift-JIS Men-Ku-Ten

1-01-35 The title given to this article is incorrect due to technical limitations. ...

EBCDIC (CCSID 500 variant)

hexadecimal (base-16): BB EBCDIC (Extended Binary Coded Decimal Interchange Code) is an 8-bit character encoding (code page) used on IBM mainframe operating systems, like z/OS, OS/390, VM and VSE, as well as IBM minicomputer operating systems like OS/400 and i5/OS. It is also employed on various non-IBM...