1 058b0118 2005-01-03 devnull .TH REGEXP9 7
  2 058b0118 2005-01-03 devnull .de EX
  3 058b0118 2005-01-03 devnull .nf
  4 058b0118 2005-01-03 devnull .ft B
  5 058b0118 2005-01-03 devnull ..
  6 058b0118 2005-01-03 devnull .de EE
  7 058b0118 2005-01-03 devnull .fi
  8 058b0118 2005-01-03 devnull .ft R
  9 058b0118 2005-01-03 devnull ..
 10 058b0118 2005-01-03 devnull .de LR
 11 058b0118 2005-01-03 devnull .if t .BR \\$1 \\$2
 12 058b0118 2005-01-03 devnull .if n .RB ` \\$1 '\\$2
 13 058b0118 2005-01-03 devnull ..
 14 058b0118 2005-01-03 devnull .de L
 15 058b0118 2005-01-03 devnull .nh
 16 058b0118 2005-01-03 devnull .if t .B \\$1
 17 058b0118 2005-01-03 devnull .if n .RB ` \\$1 '
 18 058b0118 2005-01-03 devnull ..
 19 058b0118 2005-01-03 devnull .SH NAME
 20 058b0118 2005-01-03 devnull regexp9 \- Plan 9 regular expression notation
 21 058b0118 2005-01-03 devnull .SH DESCRIPTION
 22 058b0118 2005-01-03 devnull This manual page describes the regular expression
 23 058b0118 2005-01-03 devnull syntax used by the Plan 9 regular expression library
 24 058b0118 2005-01-03 devnull .IR regexp9 (3).
 25 058b0118 2005-01-03 devnull It is the form used by
 26 058b0118 2005-01-03 devnull .IR egrep (1)
 27 058b0118 2005-01-03 devnull before
 28 058b0118 2005-01-03 devnull .I egrep
 29 058b0118 2005-01-03 devnull got complicated.
 30 058b0118 2005-01-03 devnull .PP
 31 058b0118 2005-01-03 devnull A 
 32 058b0118 2005-01-03 devnull .I "regular expression"
 33 058b0118 2005-01-03 devnull specifies
 34 058b0118 2005-01-03 devnull a set of strings of characters.
 35 058b0118 2005-01-03 devnull A member of this set of strings is said to be
 36 058b0118 2005-01-03 devnull .I matched
 37 058b0118 2005-01-03 devnull by the regular expression.  In many applications
 38 058b0118 2005-01-03 devnull a delimiter character, commonly
 39 058b0118 2005-01-03 devnull .LR / ,
 40 058b0118 2005-01-03 devnull bounds a regular expression.
 41 058b0118 2005-01-03 devnull In the following specification for regular expressions
 42 058b0118 2005-01-03 devnull the word `character' means any character (rune) but newline.
 43 058b0118 2005-01-03 devnull .PP
 44 058b0118 2005-01-03 devnull The syntax for a regular expression
 45 058b0118 2005-01-03 devnull .B e0
 46 058b0118 2005-01-03 devnull is
 47 058b0118 2005-01-03 devnull .IP
 48 058b0118 2005-01-03 devnull .EX
 49 058b0118 2005-01-03 devnull e3:  literal | charclass | '.' | '^' | '$' | '(' e0 ')'
 50 058b0118 2005-01-03 devnull 
 51 058b0118 2005-01-03 devnull e2:  e3
 52 058b0118 2005-01-03 devnull   |  e2 REP
 53 058b0118 2005-01-03 devnull 
 54 058b0118 2005-01-03 devnull REP: '*' | '+' | '?'
 55 058b0118 2005-01-03 devnull 
 56 058b0118 2005-01-03 devnull e1:  e2
 57 058b0118 2005-01-03 devnull   |  e1 e2
 58 058b0118 2005-01-03 devnull 
 59 058b0118 2005-01-03 devnull e0:  e1
 60 058b0118 2005-01-03 devnull   |  e0 '|' e1
 61 058b0118 2005-01-03 devnull .EE
 62 058b0118 2005-01-03 devnull .PP
 63 058b0118 2005-01-03 devnull A
 64 058b0118 2005-01-03 devnull .B literal
 65 058b0118 2005-01-03 devnull is any non-metacharacter, or a metacharacter
 66 058b0118 2005-01-03 devnull (one of
 67 058b0118 2005-01-03 devnull .BR .*+?[]()|\e^$ ),
 68 058b0118 2005-01-03 devnull or the delimiter
 69 058b0118 2005-01-03 devnull preceded by 
 70 058b0118 2005-01-03 devnull .LR \e .
 71 058b0118 2005-01-03 devnull .PP
 72 058b0118 2005-01-03 devnull A
 73 058b0118 2005-01-03 devnull .B charclass
 74 058b0118 2005-01-03 devnull is a nonempty string
 75 058b0118 2005-01-03 devnull .I s
 76 058b0118 2005-01-03 devnull bracketed
 77 058b0118 2005-01-03 devnull .BI [ \|s\| ]
 78 058b0118 2005-01-03 devnull (or
 79 058b0118 2005-01-03 devnull .BI [^ s\| ]\fR);
 80 058b0118 2005-01-03 devnull it matches any character in (or not in)
 81 058b0118 2005-01-03 devnull .IR s .
 82 058b0118 2005-01-03 devnull A negated character class never
 83 058b0118 2005-01-03 devnull matches newline.
 84 058b0118 2005-01-03 devnull A substring 
 85 058b0118 2005-01-03 devnull .IB a - b\f1,
 86 058b0118 2005-01-03 devnull with
 87 058b0118 2005-01-03 devnull .I a
 88 058b0118 2005-01-03 devnull and
 89 058b0118 2005-01-03 devnull .I b
 90 058b0118 2005-01-03 devnull in ascending
 91 058b0118 2005-01-03 devnull order, stands for the inclusive
 92 058b0118 2005-01-03 devnull range of
 93 058b0118 2005-01-03 devnull characters between
 94 058b0118 2005-01-03 devnull .I a
 95 058b0118 2005-01-03 devnull and
 96 058b0118 2005-01-03 devnull .IR b .
 97 058b0118 2005-01-03 devnull In 
 98 058b0118 2005-01-03 devnull .IR s ,
 99 058b0118 2005-01-03 devnull the metacharacters
100 058b0118 2005-01-03 devnull .LR - ,
101 058b0118 2005-01-03 devnull .LR ] ,
102 058b0118 2005-01-03 devnull an initial
103 058b0118 2005-01-03 devnull .LR ^ ,
104 058b0118 2005-01-03 devnull and the regular expression delimiter
105 058b0118 2005-01-03 devnull must be preceded by a
106 058b0118 2005-01-03 devnull .LR \e ;
107 058b0118 2005-01-03 devnull other metacharacters 
108 058b0118 2005-01-03 devnull have no special meaning and
109 058b0118 2005-01-03 devnull may appear unescaped.
110 058b0118 2005-01-03 devnull .PP
111 058b0118 2005-01-03 devnull A 
112 058b0118 2005-01-03 devnull .L .
113 058b0118 2005-01-03 devnull matches any character.
114 058b0118 2005-01-03 devnull .PP
115 058b0118 2005-01-03 devnull A
116 058b0118 2005-01-03 devnull .L ^
117 058b0118 2005-01-03 devnull matches the beginning of a line;
118 058b0118 2005-01-03 devnull .L $
119 058b0118 2005-01-03 devnull matches the end of the line.
120 058b0118 2005-01-03 devnull .PP
121 058b0118 2005-01-03 devnull The 
122 058b0118 2005-01-03 devnull .B REP
123 058b0118 2005-01-03 devnull operators match zero or more
124 058b0118 2005-01-03 devnull .RB ( * ),
125 058b0118 2005-01-03 devnull one or more
126 058b0118 2005-01-03 devnull .RB ( + ),
127 058b0118 2005-01-03 devnull zero or one
128 058b0118 2005-01-03 devnull .RB ( ? ),
129 058b0118 2005-01-03 devnull instances respectively of the preceding regular expression 
130 058b0118 2005-01-03 devnull .BR e2 .
131 058b0118 2005-01-03 devnull .PP
132 058b0118 2005-01-03 devnull A concatenated regular expression,
133 058b0118 2005-01-03 devnull .BR "e1\|e2" ,
134 058b0118 2005-01-03 devnull matches a match to 
135 058b0118 2005-01-03 devnull .B e1
136 058b0118 2005-01-03 devnull followed by a match to
137 058b0118 2005-01-03 devnull .BR e2 .
138 058b0118 2005-01-03 devnull .PP
139 058b0118 2005-01-03 devnull An alternative regular expression,
140 058b0118 2005-01-03 devnull .BR "e0\||\|e1" ,
141 058b0118 2005-01-03 devnull matches either a match to
142 058b0118 2005-01-03 devnull .B e0
143 058b0118 2005-01-03 devnull or a match to
144 058b0118 2005-01-03 devnull .BR e1 .
145 058b0118 2005-01-03 devnull .PP
146 058b0118 2005-01-03 devnull A match to any part of a regular expression
147 058b0118 2005-01-03 devnull extends as far as possible without preventing
148 058b0118 2005-01-03 devnull a match to the remainder of the regular expression.
149 058b0118 2005-01-03 devnull .SH "SEE ALSO"
150 058b0118 2005-01-03 devnull .IR regexp9 (3)