From 46439007cf417cbd9ac8049bb4122c890097a0fa Mon Sep 17 00:00:00 2001 From: "Charles.Forsyth" Date: Fri, 22 Dec 2006 20:52:35 +0000 Subject: 20060303-partial --- man/6/regexp | 126 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 126 insertions(+) create mode 100644 man/6/regexp (limited to 'man/6/regexp') diff --git a/man/6/regexp b/man/6/regexp new file mode 100644 index 00000000..09dea814 --- /dev/null +++ b/man/6/regexp @@ -0,0 +1,126 @@ +.TH REGEXP 6 +.SH NAME +regexp, regex \- regular expression notation +.SH DESCRIPTION +A +.I "regular expression" +specifies +a set of strings of characters. +A member of this set of strings is said to be +.I matched +by the regular expression. In many applications +a delimiter character, commonly +.LR / , +bounds a regular expression. +In the following specification for regular expressions +the word `character' means any character (rune) but newline. +.PP +The syntax for a regular expression +.B e0 +is +.IP +.EX +e3: literal | charclass | '.' | '^' | '$' | '(' e0 ')' + +e2: e3 + | e2 REP + +REP: '*' | '+' | '?' + +e1: e2 + | e1 e2 + +e0: e1 + | e0 '|' e1 +.EE +.PP +A +.B literal +is any non-metacharacter, or a metacharacter +(one of +.BR .*+?[]()|\e^$ ), +or the delimiter +preceded by +.LR \e . +.PP +A +.B charclass +is a nonempty string +.I s +bracketed +.BI [ \|s\| ] +(or +.BI [^ s\| ]\fR); +it matches any character in (or not in) +.IR s . +A negated character class never +matches newline. +A substring +.IB a - b\f1, +with +.I a +and +.I b +in ascending +order, stands for the inclusive +range of +characters between +.I a +and +.IR b . +In +.IR s , +the metacharacters +.LR - , +.LR ] , +an initial +.LR ^ , +and the regular expression delimiter +must be preceded by a +.LR \e ; +other metacharacters +have no special meaning and +may appear unescaped. +.PP +A +.L . +matches any character. +.PP +A +.L ^ +matches the beginning of a line; +.L $ +matches the end of the line. +.PP +The +.B REP +operators match zero or more +.RB ( * ), +one or more +.RB ( + ), +zero or one +.RB ( ? ), +instances respectively of the preceding regular expression +.BR e2 . +.PP +A concatenated regular expression, +.BR "e1\|e2" , +matches a match to +.B e1 +followed by a match to +.BR e2 . +.PP +An alternative regular expression, +.BR "e0\||\|e1" , +matches either a match to +.B e0 +or a match to +.BR e1 . +.PP +A match to any part of a regular expression +extends as far as possible without preventing +a match to the remainder of the regular expression. +.SH "SEE ALSO" +.IR acme (1), +.IR sh-regex (1), +.IR regex (2) -- cgit v1.2.3