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regexp(6) [plan9 man page]

REGEXP(6)							   Games Manual 							 REGEXP(6)

NAME
regexp - regular expression notation DESCRIPTION
A regular expression specifies a set of strings of characters. A member of this set of strings is said to be matched by the regular expression. In many applications a delimiter character, commonly bounds a regular expression. In the following specification for regular expressions the word `character' means any character (rune) but newline. The syntax for a regular expression e0 is e3: literal | charclass | '.' | '^' | '$' | '(' e0 ')' e2: e3 | e2 REP REP: '*' | '+' | '?' e1: e2 | e1 e2 e0: e1 | e0 '|' e1 A literal is any non-metacharacter, or a metacharacter (one of .*+?[]()|^$), or the delimiter preceded by A charclass is a nonempty string s bracketed [s] (or [^s]); it matches any character in (or not in) s. A negated character class never matches newline. A substring a-b, with a and b in ascending order, stands for the inclusive range of characters between a and b. In s, the metacharacters an initial and the regular expression delimiter must be preceded by a other metacharacters have no special meaning and may appear unescaped. A matches any character. A matches the beginning of a line; matches the end of the line. The REP operators match zero or more (*), one or more (+), zero or one (?), instances respectively of the preceding regular expression e2. A concatenated regular expression, e1e2, matches a match to e1 followed by a match to e2. An alternative regular expression, e0|e1, matches either a match to e0 or a match to e1. A match to any part of a regular expression extends as far as possible without preventing a match to the remainder of the regular expres- sion. SEE ALSO
awk(1), ed(1), sam(1), sed(1), regexp(2) REGEXP(6)

Check Out this Related Man Page

grep(1) 						      General Commands Manual							   grep(1)

Name
       grep, egrep, fgrep - search file for regular expression

Syntax
       grep [option...] expression [file...]

       egrep [option...] [expression] [file...]

       fgrep [option...] [strings] [file]

Description
       Commands  of  the family search the input files (standard input default) for lines matching a pattern.  Normally, each line found is copied
       to the standard output.

       The command patterns are limited regular expressions in the style of which uses a compact nondeterministic algorithm.  The command patterns
       are  full  regular  expressions.  The command uses a fast deterministic algorithm that sometimes needs exponential space.  The command pat-
       terns are fixed strings.  The command is fast and compact.

       In all cases the file name is shown if there is more than one input file.  Take care when using the characters $ * [ ^ | ( ) and   in  the
       expression because they are also meaningful to the Shell.  It is safest to enclose the entire expression argument in single quotes ' '.

       The command searches for lines that contain one of the (new line-separated) strings.

       The command accepts extended regular expressions.  In the following description `character' excludes new line:

	      A  followed by a single character other than new line matches that character.

	      The character ^ matches the beginning of a line.

	      The character $ matches the end of a line.

	      A .  (dot) matches any character.

	      A single character not otherwise endowed with special meaning matches that character.

	      A  string  enclosed in brackets [] matches any single character from the string.	Ranges of ASCII character codes may be abbreviated
	      as in `a-z0-9'.  A ] may occur only as the first character of the string.  A literal - must be placed where it can't be mistaken	as
	      a range indicator.

	      A  regular  expression  followed	by  an	* (asterisk) matches a sequence of 0 or more matches of the regular expression.  A regular
	      expression followed by a + (plus) matches a sequence of 1 or more matches of the regular expression.  A regular expression  followed
	      by a ? (question mark) matches a sequence of 0 or 1 matches of the regular expression.

	      Two regular expressions concatenated match a match of the first followed by a match of the second.

	      Two regular expressions separated by | or new line match either a match for the first or a match for the second.

	      A regular expression enclosed in parentheses matches a match for the regular expression.

       The  order  of  precedence  of  operators at the same parenthesis level is the following:  [], then *+?, then concatenation, then | and new
       line.

Options
       -b	   Precedes each output line with its block number.  This is sometimes useful in locating disk block numbers by context.

       -c	   Produces count of matching lines only.

       -e expression
		   Uses next argument as expression that begins with a minus (-).

       -f file	   Takes regular expression (egrep) or string list (fgrep) from file.

       -i	   Considers upper and lowercase letter identical in making comparisons and only).

       -l	   Lists files with matching lines only once, separated by a new line.

       -n	   Precedes each matching line with its line number.

       -s	   Silent mode and nothing is printed (except error messages).	This is useful for checking the error status (see DIAGNOSTICS).

       -v	   Displays all lines that do not match specified expression.

       -w	   Searches for an expression as for a word (as if surrounded by `<' and `>').  For further information, see only.

       -x	   Prints exact lines matched in their entirety only).

Restrictions
       Lines are limited to 256 characters; longer lines are truncated.

Diagnostics
       Exit status is 0 if any matches are found, 1 if none, 2 for syntax errors or inaccessible files.

See Also
       ex(1), sed(1), sh(1)

																	   grep(1)

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