132 lines
5.8 KiB
HTML
132 lines
5.8 KiB
HTML
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<title>regexp(7) - Plan 9 from User Space</title>
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<meta content="text/html; charset=utf-8" http-equiv=Content-Type>
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</head>
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<body bgcolor=#ffffff>
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<table border=0 cellpadding=0 cellspacing=0 width=100%>
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<tr height=10><td>
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<tr><td width=20><td>
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<tr><td width=20><td><b>REGEXP(7)</b><td align=right><b>REGEXP(7)</b>
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<tr><td width=20><td colspan=2>
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<br>
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<p><font size=+1><b>NAME </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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regexp – Plan 9 regular expression notation<br>
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</table>
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<p><font size=+1><b>DESCRIPTION </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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This manual page describes the regular expression syntax used
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by the Plan 9 regular expression library <a href="../man3/regexp.html"><i>regexp</i>(3)</a>. It is the
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form used by <a href="../man1/egrep.html"><i>egrep</i>(1)</a> before <i>egrep</i> got complicated.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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A <i>regular expression</i> specifies a set of strings of characters.
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A member of this set of strings is said to be <i>matched</i> by the regular
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expression. In many applications a delimiter character, commonly
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<tt><font size=+1>/</font></tt>, bounds a regular expression. In the following specification
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for regular expressions the word ‘character’ means any
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character (rune) but newline.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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The syntax for a regular expression <tt><font size=+1>e0</font></tt> is<br>
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<tt><font size=+1>e3: literal | charclass | '.' | '^' | '$' | '(' e0 ')'<br>
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e2: e3<br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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| e2 REP<br>
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</table>
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REP: '*' | '+' | '?'<br>
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e1: e2<br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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| e1 e2<br>
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</table>
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e0: e1<br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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| e0 '|' e1<br>
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</table>
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</font></tt>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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</table>
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</table>
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A <tt><font size=+1>literal</font></tt> is any non-metacharacter, or a metacharacter (one of
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<tt><font size=+1>.*+?[]()|\^$</font></tt>), or the delimiter preceded by <tt><font size=+1>\</font></tt>.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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A <tt><font size=+1>charclass</font></tt> is a nonempty string <i>s</i> bracketed <tt><font size=+1>[</font></tt><i>s</i><tt><font size=+1>]</font></tt> (or <tt><font size=+1>[^</font></tt><i>s</i><tt><font size=+1>]</font></tt>); it
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matches any character in (or not in) <i>s</i>. A negated character class
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never matches newline. A substring <i>a</i><tt><font size=+1>−</font></tt><i>b</i>, with <i>a</i> and <i>b</i> in ascending
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order, stands for the inclusive range of characters between <i>a</i>
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and <i>b</i>. In <i>s</i>, the metacharacters <tt><font size=+1>−</font></tt>, <tt><font size=+1>]</font></tt>, an initial <tt><font size=+1>^</font></tt>, and the
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regular expression delimiter must be preceded by a <tt><font size=+1>\</font></tt>; other metacharacters
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have no special meaning and may appear unescaped.
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A <tt><font size=+1>.</font></tt> matches any character.
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A <tt><font size=+1>^</font></tt> matches the beginning of a line; <tt><font size=+1>$</font></tt> matches the end of the
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line.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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The <tt><font size=+1>REP</font></tt> operators match zero or more (<tt><font size=+1>*</font></tt>), one or more (<tt><font size=+1>+</font></tt>), zero
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or one (<tt><font size=+1>?</font></tt>), instances respectively of the preceding regular expression
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<tt><font size=+1>e2</font></tt>.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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A concatenated regular expression, <tt><font size=+1>e1e2</font></tt>, matches a match to <tt><font size=+1>e1</font></tt>
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followed by a match to <tt><font size=+1>e2</font></tt>.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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An alternative regular expression, <tt><font size=+1>e0|e1</font></tt>, matches either a match
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to <tt><font size=+1>e0</font></tt> or a match to <tt><font size=+1>e1</font></tt>.
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<table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table>
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A match to any part of a regular expression extends as far as
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possible without preventing a match to the remainder of the regular
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expression.<br>
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</table>
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<p><font size=+1><b>SEE ALSO </b></font><br>
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<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td>
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<a href="../man3/regexp.html"><i>regexp</i>(3)</a><br>
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</table>
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<td width=20>
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<tr height=20><td>
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</table>
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<!-- TRAILER -->
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<table border=0 cellpadding=0 cellspacing=0 width=100%>
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<tr height=15><td width=10><td><td width=10>
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<tr><td><td>
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<center>
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<a href="../../"><img src="../../dist/spaceglenda100.png" alt="Space Glenda" border=1></a>
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</center>
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</table>
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<!-- TRAILER -->
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</body></html>
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