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596 lines
26 KiB
XML
<?xml version="1.0" encoding="UTF-8" ?>
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<!DOCTYPE manualpage SYSTEM "./style/manualpage.dtd">
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<?xml-stylesheet type="text/xsl" href="./style/manual.en.xsl"?>
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<!-- $LastChangedRevision$ -->
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<!--
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<manualpage metafile="expr.xml.meta">
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<title>Expressions in Apache HTTP Server</title>
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<summary>
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<p>Historically, there are several syntax variants for expressions used to express
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a condition in the different modules of the Apache HTTP Server.
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There is some ongoing effort to only use a single variant, called <em>ap_expr</em>,
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for all configuration directives.
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This document describes the <em>ap_expr</em> expression parser.
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</p>
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<p>The <em>ap_expr</em> expression is intended to replace most other
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expression variants in HTTPD. For example, the deprecated
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<directive module="mod_ssl">SSLRequire</directive> expressions can be
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replaced by <a href="mod/mod_authz_core.html#reqexpr">Require expr</a>.
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</p>
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</summary>
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<seealso><directive module="core" type="section">If</directive></seealso>
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<seealso><directive module="core" type="section">ElseIf</directive></seealso>
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<seealso><directive module="core" type="section">Else</directive></seealso>
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<seealso><directive module="mod_auth_basic">AuthBasicFake</directive></seealso>
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<seealso><directive module="mod_auth_form">AuthFormLoginRequiredLocation</directive></seealso>
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<seealso><directive module="mod_auth_form">AuthFormLoginSuccessLocation</directive></seealso>
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<seealso><directive module="mod_auth_form">AuthFormLogoutLocation</directive></seealso>
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<seealso><directive module="mod_rewrite">RewriteCond</directive></seealso>
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<seealso><directive module="mod_setenvif">SetEnvIfExpr</directive></seealso>
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<seealso><directive module="mod_headers">Header</directive></seealso>
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<seealso><directive module="mod_headers">RequestHeader</directive></seealso>
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<seealso><directive module="mod_filter">FilterProvider</directive></seealso>
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<seealso><a href="mod/mod_authz_core.html#reqexpr">Require expr</a></seealso>
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<seealso><directive module="mod_ssl">SSLRequire</directive></seealso>
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<seealso><directive module="mod_log_debug">LogMessage</directive></seealso>
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<seealso><module>mod_include</module></seealso>
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<section id="grammar">
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<title>Grammar in Backus-Naur Form notation</title>
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<p><a href="http://en.wikipedia.org/wiki/Backus%E2%80%93Naur_Form">Backus-Naur Form</a> (BNF) is a notation
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technique for context-free grammars, often used to describe the syntax of languages used in computing.
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In most cases, expressions are used to express boolean values.
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For these, the starting point in the BNF is <code>expr</code>. However, a few directives
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like <directive module="mod_log_debug">LogMessage</directive> accept expressions
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that evaluate to a string value. For those, the starting point in the BNF is <code>string</code>.
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</p>
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<blockquote>
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<pre>
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expr ::= "<strong>true</strong>" | "<strong>false</strong>"
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| "<strong>!</strong>" expr
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| expr "<strong>&&</strong>" expr
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| expr "<strong>||</strong>" expr
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| "<strong>(</strong>" expr "<strong>)</strong>"
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| comp
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comp ::= stringcomp
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| integercomp
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| unaryop word
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| word binaryop word
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| word "<strong>in</strong>" "<strong>{</strong>" wordlist "<strong>}</strong>"
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| word "<strong>in</strong>" listfunction
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| word "<strong>=~</strong>" regex
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| word "<strong>!~</strong>" regex
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stringcomp ::= word "<strong>==</strong>" word
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| word "<strong>!=</strong>" word
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| word "<strong><</strong>" word
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| word "<strong><=</strong>" word
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| word "<strong>></strong>" word
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| word "<strong>>=</strong>" word
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integercomp ::= word "<strong>-eq</strong>" word | word "<strong>eq</strong>" word
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| word "<strong>-ne</strong>" word | word "<strong>ne</strong>" word
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| word "<strong>-lt</strong>" word | word "<strong>lt</strong>" word
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| word "<strong>-le</strong>" word | word "<strong>le</strong>" word
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| word "<strong>-gt</strong>" word | word "<strong>gt</strong>" word
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| word "<strong>-ge</strong>" word | word "<strong>ge</strong>" word
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wordlist ::= word
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| wordlist "<strong>,</strong>" word
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word ::= word "<strong>.</strong>" word
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| digit
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| "<strong>'</strong>" string "<strong>'</strong>"
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| "<strong>"</strong>" string "<strong>"</strong>"
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| variable
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| rebackref
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| function
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string ::= stringpart
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| string stringpart
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stringpart ::= cstring
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| variable
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| rebackref
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cstring ::= ...
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digit ::= [0-9]+
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variable ::= "<strong>%{</strong>" varname "<strong>}</strong>"
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| "<strong>%{</strong>" funcname "<strong>:</strong>" funcargs "<strong>}</strong>"
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rebackref ::= "<strong>$</strong>" [0-9]
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function ::= funcname "<strong>(</strong>" word "<strong>)</strong>"
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listfunction ::= listfuncname "<strong>(</strong>" word "<strong>)</strong>"
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</pre>
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</blockquote>
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</section>
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<section id="vars">
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<title>Variables</title>
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<p>The expression parser provides a number of variables of the form
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<code>%{HTTP_HOST}</code>. Note that the value of a variable may depend
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on the phase of the request processing in which it is evaluated. For
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example, an expression used in an <directive><If ></directive>
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directive is evaluated before authentication is done. Therefore,
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<code>%{REMOTE_USER}</code> will not be set in this case.</p>
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<p>The following variables provide the values of the named HTTP request
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headers. The values of other headers can be obtained with the
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<code>req</code> <a href="#functions">function</a>. Using these
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variables may cause the header name to be added to the Vary
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header of the HTTP response, except where otherwise noted for the
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directive accepting the expression. The <code>req_novary</code>
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<a href="#functions">function</a> may be used to circumvent this
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behavior.</p>
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<table border="1" style="zebra">
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<columnspec><column width="1"/></columnspec>
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<tr><th>Name</th></tr>
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<tr><td><code>HTTP_ACCEPT</code></td></tr>
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<tr><td><code>HTTP_FORWARDED</code></td></tr>
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<tr><td><code>HTTP_HOST</code></td></tr>
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<tr><td><code>HTTP_PROXY_CONNECTION</code></td></tr>
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<tr><td><code>HTTP_REFERER</code></td></tr>
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<tr><td><code>HTTP_USER_AGENT</code></td></tr>
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</table>
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<p>Other request related variables</p>
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<table border="1" style="zebra">
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<columnspec><column width=".4"/><column width=".6"/></columnspec>
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<tr><th>Name</th><th>Description</th></tr>
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<tr><td><code>REQUEST_METHOD</code></td>
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<td>The HTTP method of the incoming request (e.g.
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<code>GET</code>)</td></tr>
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<tr><td><code>REQUEST_SCHEME</code></td>
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<td>The scheme part of the request's URI</td></tr>
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<tr><td><code>REQUEST_URI</code></td>
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<td>The path part of the request's URI</td></tr>
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<tr><td><code>DOCUMENT_URI</code></td>
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<td>Same as REQUEST_URI</td></tr>
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<tr><td><code>REQUEST_FILENAME</code></td>
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<td>The full local filesystem path to the file or script matching the
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request, if this has already been determined by the server at the
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time <code>REQUEST_FILENAME</code> is referenced. Otherwise, such
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as when used in virtual host context, the same value as
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<code>REQUEST_URI</code> </td></tr>
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<tr><td><code>SCRIPT_FILENAME</code></td>
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<td>Same as <code>REQUEST_FILENAME</code></td></tr>
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<tr><td><code>LAST_MODIFIED</code></td>
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<td>The date and time of last modification of the file in the format
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<code>20101231235959</code>, if this has already been determined by
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the server at the time <code>LAST_MODIFIED</code> is referenced.
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</td></tr>
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<tr><td><code>SCRIPT_USER</code></td>
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<td>The user name of the owner of the script.</td></tr>
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<tr><td><code>SCRIPT_GROUP</code></td>
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<td>The group name of the group of the script.</td></tr>
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<tr><td><code>PATH_INFO</code></td>
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<td>The trailing path name information, see
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<directive module="core">AcceptPathInfo</directive></td></tr>
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<tr><td><code>QUERY_STRING</code></td>
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<td>The query string of the current request</td></tr>
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<tr><td><code>IS_SUBREQ</code></td>
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<td>"<code>true</code>" if the current request is a subrequest,
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"<code>false</code>" otherwise</td></tr>
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<tr><td><code>THE_REQUEST</code></td>
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<td>The complete request line (e.g.,
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"<code>GET /index.html HTTP/1.1</code>")</td></tr>
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<tr><td><code>REMOTE_ADDR</code></td>
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<td>The IP address of the remote host</td></tr>
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<tr><td><code>REMOTE_HOST</code></td>
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<td>The host name of the remote host</td></tr>
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<tr><td><code>REMOTE_USER</code></td>
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<td>The name of the authenticated user (if any)</td></tr>
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<tr><td><code>REMOTE_IDENT</code></td>
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<td>The user name set by <module>mod_ident</module></td></tr>
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<tr><td><code>SERVER_NAME</code></td>
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<td>The <directive module="core">ServerName</directive> of
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the current vhost</td></tr>
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<tr><td><code>SERVER_PORT</code></td>
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<td>The server port of the current vhost, see
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<directive module="core">ServerName</directive></td></tr>
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<tr><td><code>SERVER_ADMIN</code></td>
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<td>The <directive module="core">ServerAdmin</directive> of
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the current vhost</td></tr>
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<tr><td><code>SERVER_PROTOCOL</code></td>
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<td>The protocol used by the request (e.g. HTTP/1.1). In some types of
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internal subrequests, this variable has the value
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<code>INCLUDED</code>.</td></tr>
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<tr><td><code>SERVER_PROTOCOL_VERSION</code></td>
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<td>A number that encodes the HTTP version of the request:
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<code>1000 * major + minor</code>. For example, <code>1001</code>
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corresponds to HTTP/1.1 and <code>9</code> corresponds
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to HTTP/0.9</td></tr>
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<tr><td><code>SERVER_PROTOCOL_VERSION_MAJOR</code></td>
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<td>The major version part of the HTTP version of the request,
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e.g. <code>1</code> for HTTP/1.0</td></tr>
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<tr><td><code>SERVER_PROTOCOL_VERSION_MINOR</code></td>
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<td>The minor version part of the HTTP version of the request,
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e.g. <code>0</code> for HTTP/1.0</td></tr>
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<tr><td><code>DOCUMENT_ROOT</code></td>
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<td>The <directive module="core">DocumentRoot</directive> of
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the current vhost</td></tr>
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<tr><td><code>AUTH_TYPE</code></td>
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<td>The configured <directive module="mod_authn_core">AuthType</directive>
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(e.g. "<code>basic</code>")</td></tr>
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<tr><td><code>CONTENT_TYPE</code></td>
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<td>The content type of the response</td></tr>
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<tr><td><code>HANDLER</code></td>
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<td>The name of the <a href="handler.html">handler</a> creating
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the response</td></tr>
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<tr><td><code>HTTPS</code></td>
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<td>"<code>on</code>" if the request uses https,
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"<code>off</code>" otherwise</td></tr>
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<tr><td><code>IPV6</code></td>
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<td>"<code>on</code>" if the connection uses IPv6,
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"<code>off</code>" otherwise</td></tr>
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<tr><td><code>REQUEST_STATUS</code></td>
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<td>The HTTP error status of the request</td></tr>
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<tr><td><code>REQUEST_LOG_ID</code></td>
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<td>The error log id of the request (see
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<directive module="core">ErrorLogFormat</directive>)</td></tr>
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<tr><td><code>CONN_LOG_ID</code></td>
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<td>The error log id of the connection (see
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<directive module="core">ErrorLogFormat</directive>)</td></tr>
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<tr><td><code>CONN_REMOTE_ADDR</code></td>
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<td>The peer IP address of the connection (see the
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<module>mod_remoteip</module> module)</td></tr>
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</table>
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<p>Misc variables</p>
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<table border="1" style="zebra">
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<columnspec><column width=".4"/><column width=".6"/></columnspec>
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<tr><th>Name</th><th>Description</th></tr>
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<tr><td><code>TIME_YEAR</code></td>
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<td>The current year (e.g. <code>2010</code>)</td></tr>
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<tr><td><code>TIME_MON</code></td>
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<td>The current month (<code>1</code>, ..., <code>12</code>)</td></tr>
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<tr><td><code>TIME_DAY</code></td>
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<td>The current day of the month</td></tr>
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<tr><td><code>TIME_HOUR</code></td>
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<td>The hour part of the current time
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(<code>0</code>, ..., <code>23</code>)</td></tr>
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<tr><td><code>TIME_MIN</code></td>
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<td>The minute part of the current time </td></tr>
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<tr><td><code>TIME_SEC</code></td>
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<td>The second part of the current time </td></tr>
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<tr><td><code>TIME_WDAY</code></td>
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<td>The day of the week (starting with <code>0</code>
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for Sunday)</td></tr>
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<tr><td><code>TIME</code></td>
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<td>The date and time in the format <code>20101231235959</code></td></tr>
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<tr><td><code>SERVER_SOFTWARE</code></td>
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<td>The server version string</td></tr>
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<tr><td><code>API_VERSION</code></td>
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<td>The date of the API version (module magic number)</td></tr>
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</table>
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<p>Some modules register additional variables, see e.g. <module>mod_ssl</module>.</p>
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</section>
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<section id="binop">
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<title>Binary operators</title>
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<p>With the exception of some built-in comparison operators, binary
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operators have the form "<code>-[a-zA-Z][a-zA-Z0-9_]+</code>", i.e. a
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minus and at least two characters. The name is not case sensitive.
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Modules may register additional binary operators.</p>
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<section id="comp">
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<title>Comparison operators</title>
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<table border="1" style="zebra">
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<columnspec><column width=".2"/><column width=".2"/><column width=".6"/></columnspec>
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<tr><th>Name</th><th>Alternative</th> <th>Description</th></tr>
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<tr><td><code>==</code></td>
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<td><code>=</code></td>
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<td>String equality</td></tr>
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<tr><td><code>!=</code></td>
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<td></td>
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<td>String inequality</td></tr>
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<tr><td><code><</code></td>
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<td></td>
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<td>String less than</td></tr>
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<tr><td><code><=</code></td>
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<td></td>
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<td>String less than or equal</td></tr>
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<tr><td><code>></code></td>
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<td></td>
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<td>String greater than</td></tr>
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<tr><td><code>>=</code></td>
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<td></td>
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<td>String greater than or equal</td></tr>
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<tr><td><code>-eq</code></td>
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<td><code>eq</code></td>
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<td>Integer equality</td></tr>
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<tr><td><code>-ne</code></td>
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<td><code>ne</code></td>
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<td>Integer inequality</td></tr>
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<tr><td><code>-lt</code></td>
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<td><code>lt</code></td>
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<td>Integer less than</td></tr>
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<tr><td><code>-le</code></td>
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<td><code>le</code></td>
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<td>Integer less than or equal</td></tr>
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<tr><td><code>-gt</code></td>
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<td><code>gt</code></td>
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<td>Integer greater than</td></tr>
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<tr><td><code>-ge</code></td>
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<td><code>ge</code></td>
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<td>Integer greater than or equal</td></tr>
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</table>
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</section>
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<section id="binaryother">
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<title>Other binary operators</title>
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<table border="1" style="zebra">
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<columnspec><column width=".2"/><column width=".8"/></columnspec>
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<tr><th>Name</th><th>Description</th></tr>
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<tr><td><code>-ipmatch</code></td>
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<td>IP address matches address/netmask</td></tr>
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<tr><td><code>-strmatch</code></td>
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<td>left string matches pattern given by right string (containing
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wildcards *, ?, [])</td></tr>
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<tr><td><code>-strcmatch</code></td>
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<td>same as <code>-strmatch</code>, but case insensitive</td></tr>
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<tr><td><code>-fnmatch</code></td>
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<td>same as <code>-strmatch</code>, but slashes are not matched by
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wildcards</td></tr>
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</table>
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</section>
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</section>
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<section id="unnop">
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<title>Unary operators</title>
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<p>Unary operators take one argument and have the form
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"<code>-[a-zA-Z]</code>", i.e. a minus and one character.
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The name <em>is</em> case sensitive.
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Modules may register additional unary operators.</p>
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<table border="1" style="zebra">
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<columnspec><column width=".2"/><column width=".2"/><column width=".6"/></columnspec>
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<tr><th>Name</th><th>Description</th><th>Restricted</th></tr>
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<tr><td><code>-d</code></td>
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<td>The argument is treated as a filename.
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True if the file exists and is a directory</td><td>yes</td></tr>
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<tr><td><code>-e</code></td>
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<td>The argument is treated as a filename.
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True if the file (or dir or special) exists</td><td>yes</td></tr>
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<tr><td><code>-f</code></td>
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<td>The argument is treated as a filename.
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True if the file exists and is regular file</td><td>yes</td></tr>
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<tr><td><code>-s</code></td>
|
|
<td>The argument is treated as a filename.
|
|
True if the file exists and is not empty</td><td>yes</td></tr>
|
|
<tr><td><code>-L</code></td>
|
|
<td>The argument is treated as a filename.
|
|
True if the file exists and is symlink</td><td>yes</td></tr>
|
|
<tr><td><code>-h</code></td>
|
|
<td>The argument is treated as a filename.
|
|
True if the file exists and is symlink
|
|
(same as <code>-L</code>)</td><td>yes</td></tr>
|
|
<tr><td><code>-F</code></td>
|
|
<td>True if string is a valid file, accessible via all the server's
|
|
currently-configured access controls for that path. This uses an
|
|
internal subrequest to do the check, so use it with care - it can
|
|
impact your server's performance!</td><td></td></tr>
|
|
<tr><td><code>-U</code></td>
|
|
<td>True if string is a valid URL, accessible via all the server's
|
|
currently-configured access controls for that path. This uses an
|
|
internal subrequest to do the check, so use it with care - it can
|
|
impact your server's performance!</td><td></td></tr>
|
|
<tr><td><code>-A</code></td>
|
|
<td>Alias for <code>-U</code></td><td></td></tr>
|
|
<tr><td><code>-n</code></td>
|
|
<td>True if string is not empty</td><td></td></tr>
|
|
<tr><td><code>-z</code></td>
|
|
<td>True if string is empty</td><td></td></tr>
|
|
<tr><td><code>-T</code></td>
|
|
<td>False if string is empty, "<code>0</code>", "<code>off</code>",
|
|
"<code>false</code>", or "<code>no</code>" (case insensitive).
|
|
True otherwise.</td><td></td></tr>
|
|
<tr><td><code>-R</code></td>
|
|
<td>Same as "<code>%{REMOTE_ADDR} -ipmatch ...</code>", but more efficient
|
|
</td><td></td></tr>
|
|
</table>
|
|
|
|
<p>The operators marked as "restricted" are not available in some modules
|
|
like <module>mod_include</module>.</p>
|
|
</section>
|
|
|
|
<section id="functions">
|
|
<title>Functions</title>
|
|
|
|
<p>Normal string-valued functions take one string as argument and return
|
|
a string. Functions names are not case sensitive.
|
|
Modules may register additional functions.</p>
|
|
|
|
<table border="1" style="zebra">
|
|
<columnspec><column width=".2"/><column width=".8"/></columnspec>
|
|
|
|
<tr><th>Name</th><th>Description</th><th>Restricted</th></tr>
|
|
<tr><td><code>req</code>, <code>http</code></td>
|
|
<td>Get HTTP request header; header names may be added to the Vary
|
|
header, see below</td><td></td></tr>
|
|
<tr><td><code>req_novary</code></td>
|
|
<td>Same as <code>req</code>, but header names will not be added to the
|
|
Vary header</td><td></td></tr>
|
|
<tr><td><code>resp</code></td>
|
|
<td>Get HTTP response header</td><td></td></tr>
|
|
<tr><td><code>reqenv</code></td>
|
|
<td>Lookup request environment variable (as a shortcut, <code>v</code> can be used too to access variables).</td><td></td></tr>
|
|
<tr><td><code>osenv</code></td>
|
|
<td>Lookup operating system environment variable</td><td></td></tr>
|
|
<tr><td><code>note</code></td>
|
|
<td>Lookup request note</td><td></td></tr>
|
|
<tr><td><code>env</code></td>
|
|
<td>Return first match of <code>note</code>, <code>reqenv</code>,
|
|
<code>osenv</code></td><td></td></tr>
|
|
<tr><td><code>tolower</code></td>
|
|
<td>Convert string to lower case</td><td></td></tr>
|
|
<tr><td><code>toupper</code></td>
|
|
<td>Convert string to upper case</td><td></td></tr>
|
|
<tr><td><code>escape</code></td>
|
|
<td>Escape special characters in %hex encoding</td><td></td></tr>
|
|
<tr><td><code>unescape</code></td>
|
|
<td>Unescape %hex encoded string, leaving encoded slashes alone;
|
|
return empty string if %00 is found</td><td></td></tr>
|
|
<tr><td><code>base64</code></td>
|
|
<td>Encode the string using base64 encoding</td><td></td></tr>
|
|
<tr><td><code>unbase64</code></td>
|
|
<td>Decode base64 encoded string, return truncated string if 0x00 is
|
|
found</td><td></td></tr>
|
|
<tr><td><code>md5</code></td>
|
|
<td>Hash the string using MD5, then encode the hash with hexadecimal
|
|
encoding</td><td></td></tr>
|
|
<tr><td><code>sha1</code></td>
|
|
<td>Hash the string using SHA1, then encode the hash with hexadecimal
|
|
encoding</td><td></td></tr>
|
|
<tr><td><code>file</code></td>
|
|
<td>Read contents from a file</td><td>yes</td></tr>
|
|
<tr><td><code>filesize</code></td>
|
|
<td>Return size of a file (or 0 if file does not exist or is not
|
|
regular file)</td><td>yes</td></tr>
|
|
|
|
</table>
|
|
|
|
<p>The functions marked as "restricted" are not available in some modules
|
|
like <module>mod_include</module>.</p>
|
|
|
|
<p>When the functions <code>req</code> or <code>http</code> are used,
|
|
the header name will automatically be added to the Vary header of the
|
|
HTTP response, except where otherwise noted for the directive accepting
|
|
the expression. The <code>req_novary</code> function can be used to
|
|
prevent names from being added to the Vary header.</p>
|
|
|
|
<p>In addition to string-valued functions, there are also list-valued functions which
|
|
take one string as argument and return a wordlist, i.e. a list of strings. The wordlist
|
|
can be used with the special <code>-in</code> operator.
|
|
Functions names are not case sensitive.
|
|
Modules may register additional functions.</p>
|
|
|
|
<p>There are no built-in list-valued functions. <module>mod_ssl</module>
|
|
provides <code>PeerExtList</code>. See the description of
|
|
<directive module="mod_ssl">SSLRequire</directive> for details
|
|
(but <code>PeerExtList</code> is also usable outside
|
|
of <directive module="mod_ssl">SSLRequire</directive>).</p>
|
|
|
|
</section>
|
|
|
|
<section id="examples">
|
|
|
|
<title>Example expressions</title>
|
|
<p>The following examples show how expressions might be used to evaluate requests:</p>
|
|
<!-- This section should probably be extended with more, useful examples -->
|
|
<highlight language="config">
|
|
# Compare the host name to example.com and redirect to www.example.com if it matches
|
|
<If "%{HTTP_HOST} == 'example.com'">
|
|
Redirect permanent / http://www.example.com/
|
|
</If>
|
|
|
|
# Force text/plain if requesting a file with the query string contains 'forcetext'
|
|
<If "%{QUERY_STRING} =~ /forcetext/">
|
|
ForceType text/plain
|
|
</If>
|
|
|
|
# Only allow access to this content during business hours
|
|
<Directory "/foo/bar/business">
|
|
Require expr "%{TIME_HOUR} -gt 9 && %{TIME_HOUR} -lt 17"
|
|
</Directory>
|
|
</highlight>
|
|
</section>
|
|
|
|
<section id="other">
|
|
<title>Other</title>
|
|
|
|
<table border="1" style="zebra">
|
|
<columnspec><column width=".2"/><column width=".2"/><column width=".6"/></columnspec>
|
|
|
|
<tr><th>Name</th><th>Alternative</th> <th>Description</th></tr>
|
|
<tr><td><code>-in</code></td>
|
|
<td><code>in</code></td>
|
|
<td>string contained in string list</td></tr>
|
|
<tr><td><code>/regexp/</code></td>
|
|
<td><code>m#regexp#</code></td>
|
|
<td>Regular expression (the second form allows different delimiters than /)</td></tr>
|
|
<tr><td><code>/regexp/i</code></td>
|
|
<td><code>m#regexp#i</code></td>
|
|
<td>Case insensitive regular expression</td></tr>
|
|
<tr><td><code>$0 ... $9</code></td>
|
|
<td></td>
|
|
<td>Regular expression backreferences</td></tr>
|
|
</table>
|
|
|
|
<section id="rebackref">
|
|
<title>Regular expression backreferences</title>
|
|
<p>The strings <code>$0</code> ... <code>$9</code> allow to reference
|
|
the capture groups from a previously executed, successfully
|
|
matching regular expressions. They can normally only be used in the
|
|
same expression as the matching regex, but some modules allow special
|
|
uses.</p>
|
|
</section>
|
|
|
|
</section>
|
|
|
|
<section id="sslrequire">
|
|
<title>Comparison with SSLRequire</title>
|
|
<p>The <em>ap_expr</em> syntax is mostly a superset of the syntax of the
|
|
deprecated <directive module="mod_ssl">SSLRequire</directive> directive.
|
|
The differences are described in <directive
|
|
module="mod_ssl">SSLRequire</directive>'s documentation.</p>
|
|
</section>
|
|
|
|
<section id="compatibility">
|
|
<title>Version History</title>
|
|
<p>The <code>req_novary</code> <a href="#functions">function</a>
|
|
is available for versions 2.4.4 and later.</p>
|
|
<p>The <code>SERVER_PROTOCOL_VERSION</code>,
|
|
<code>SERVER_PROTOCOL_VERSION_MAJOR</code> and
|
|
<code>SERVER_PROTOCOL_VERSION_MINOR</code>
|
|
<a href="#vars">variables</a>
|
|
are available for versions 2.5.0 and later.</p>
|
|
</section>
|
|
|
|
</manualpage>
|