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Information about Escape Character

In computing and telecommunication, an escape character is a single character which in a sequence of characters signifies that what is to follow takes an alternative interpretation. The term escape sequence refers to the escape character and the subsequent character or characters so modified.

Examples

Bourne shell

In sh, the * character is special, expanding via globbing. In isolation, it expands to the names of all files in the current directory. So to refer to a file literally called * you need to tell the shell to not interpret it in this way, which you do by preceding it with a backslash (\) -- this escapes the * character. Compare:

rm * = delete all files in the current directory

rm \* = delete the file named *

Programming languages

Many modern programming languages specify the doublequote character (") as a delimiter for a string literal. The backslash escape character provides one way to include doublequotes inside a string literal. For example, in Perl:

print "Nancy said "Hello World!" to the crowd.";

produces a syntax error, whereas:

print "Nancy said \"Hello World!\" to the crowd.";

produces the intended output.

Some programming languages also provide other ways to prevent this type of error, without requiring an escape character (see e.g. delimiter collision).

Categories

  • In alphabet coding schemes, a specially designated character, the occurrence of which in the data signifies that one or more of the characters to follow are from a different character code, i.e., have meanings other than normal.
  • In a text-control sequence of characters, a control character that indicates the beginning of the sequence and the end of any preceding text. This is for instance used to control text terminals and printers (see escape sequence).
  • In the ASCII character code, the character ESC with decimal code 27 and hexadecimal code 1B.
Early reference to this term is found in Bob Bemer's IBM technical publications.

Some of this article is based on material from Federal Standard 1037C.

The Escape key is usually found on standard PC keyboards. However it is commonly absent from keyboards for PDAs and other devices not designed primarily for ASCII communications, and not generally used as part of the common user interface for applications on the Windows operating system. The DEC VT220 series was one of the few popular keyboards that did not have a dedicated Esc key, instead using one of the keys above the main keypad, though it is debatable if this contributed to the failure of the DEC personal computer series that used this keyboard.

External links

See also

computing is synonymous with counting and calculating. Originally, people that performed these functions were known as computers. Today it refers to a science and technology that deals with the computation and the manipulation of symbols.
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Telecommunication is the transmission of signals over a distance for the purpose of communication. In modern times, this process typically involves the sending of electromagnetic waves by electronic transmitters, but in earlier times telecommunication may have involved the use of
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This article refers to codes used as commands for computing devices. Escape sequence can also refer to a sequence of escape characters used in parsing source code.

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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. It was developed by Stephen Bourne, of AT&T Bell Laboratories, and was released in 1977 in the Version 7 Unix release
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glob() is a Unix library function that expands file names using a pattern matching notation reminiscent of regular expression syntax but without the expressive power of true regular expressions. The word "glob" is also used as a noun when discussing a particular pattern, e.g.
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A programming language is an artificial language that can be used to control the behavior of a machine, particularly a computer. Programming languages, like natural languagess, are defined by syntactic and semantic rules which describe their structure and meaning respectively.
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delimiter is a sequence of one or more characters used to specify the boundary between separate, independent regions in plain text or other data stream.[1] An example of a delimiter is the comma character in a sequence of comma-separated values.
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A string literal is the representation of a string value within the source code of a computer program. There exist numerous alternate notations for specifying string literals, and the exact notation depends on the individual programming language in question.
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Perl

Paradigm: Multi-paradigm
Appeared in: 1987
Designed by: Larry Wall
Latest release: 5.8.8/ January 31 2006
Typing discipline: Dynamic
Influenced by: AWK, BASIC, BASIC-PLUS, C, C++, Lisp, Pascal, Python, sed, Unix shell
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ABCs redirects here, for the Alien Big Cats, see British big cats.


An alphabet is a standardized set of letters
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The term coding has the following meanings:
  • In communications systems, the altering of the characteristics of a signal to make the signal more suitable for an intended application, such as optimizing the signal for transmission, improving transmission quality and fidelity,

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character is a unit of information that roughly corresponds to a grapheme, grapheme-like unit, or symbol, such as in an alphabet or syllabary in the written form of a natural language.

An example of a character is a letter, numeral, or punctuation mark.
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For other uses, see Data (disambiguation).


Debt, AIDS, Trade in Africa (or DATA) is a multinational non-government organization founded in January 2002 in London by U2's Bono along with Bobby Shriver and activists from the Jubilee 2000 Drop
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In communications, a code is a rule for converting a piece of information (for example, a letter, word, or phrase) into another form or representation, not necessarily of the same type.
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sequence is an ordered list of objects (or events). Like a set, it contains members (also called elements or terms), and the number of terms (possibly infinite) is called the length of the sequence.
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In computing and telecommunication, a control character or non-printing character is a code point (a number) in a character set that does not in itself represent a written symbol.
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A computer terminal is an electronic or electromechanical hardware device that is used for entering data into, and displaying data from, a computer or a computing system. A computer terminal is an instance of a human-machine interface(HMI).
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This article refers to codes used as commands for computing devices. Escape sequence can also refer to a sequence of escape characters used in parsing source code.

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American Standard Code for Information Interchange (ASCII), generally pronounced ask-ee IPA: /ˈæski/ ( [1] ), is a character encoding based on the English alphabet.
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decimal (base ten or occasionally denary) numeral system has ten as its base. It is the most widely used numeral system, perhaps because humans have four fingers and a thumb on each hand, giving a total of ten digits over both hands.
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hexadecimal, base-16, or simply hex, is a numeral system with a radix, or base, of 16, usually written using the symbols 0–9 and A–F, or a–f.
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Robert William Bemer (February 8, 1920 – June 22, 2004) was a computer scientist best known for his work at IBM during the late 1950s and early 1960s.[1]

Born in Sault Ste. Marie, Michigan, Bemer graduated from Cranbrook School in 1936 and took an A.B.
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Federal Standard 1037C, entitled Telecommunications: Glossary of Telecommunication Terms is a United States Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended.
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Esc key is in the top-left corner.]]

The Esc key is a key labeled Esc or Escape that is used to generate the ASCII Escape character (Control-[, ASCII code 27 in decimal), the character code traditionally used to initiate an escape sequence.
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Robert William Bemer (February 8, 1920 – June 22, 2004) was a computer scientist best known for his work at IBM during the late 1950s and early 1960s.[1]

Born in Sault Ste. Marie, Michigan, Bemer graduated from Cranbrook School in 1936 and took an A.B.
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Esc key is in the top-left corner.]]

The Esc key is a key labeled Esc or Escape that is used to generate the ASCII Escape character (Control-[, ASCII code 27 in decimal), the character code traditionally used to initiate an escape sequence.
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This article refers to codes used as commands for computing devices. Escape sequence can also refer to a sequence of escape characters used in parsing source code.

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ANSI escape codes are used to control text formatting and other output options on text terminals. In this context, ANSI refers to the ANSI X3.64 standard (which was withdrawn in 1997). It was replaced by ISO/IEC 6429, and is equivalent to ECMA-48.
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delimiter is a sequence of one or more characters used to specify the boundary between separate, independent regions in plain text or other data stream.[1] An example of a delimiter is the comma character in a sequence of comma-separated values.
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A metacharacter is a character that has a special meaning (instead of a literal meaning) to a computer program, such as a shell interpreter or a regular expression engine.

Examples

  • In some Unix shells, the ; (semicolon) character is a statement separator.

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