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./faq/">FAQ</a> | <a href="./glossary.html">Glossary</a> | <a href="./sitemap.html">Sitemap</a></p>
+<p class="menu"><a href="./mod/">Modules</a> | <a href="./mod/directives.html">Directives</a> | <a href="
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<p class="apache">Apache HTTP Server Version 2.5</p>
<img alt="" src="./images/feather.gif" /></div>
<div class="up"><a href="./"><img title="<-" alt="<-" src="./images/left.gif" /></a></div>
<li><img alt="" src="./images/down.gif" /> <a href="#examples">Example expressions</a></li>
<li><img alt="" src="./images/down.gif" /> <a href="#other">Other</a></li>
<li><img alt="" src="./images/down.gif" /> <a href="#sslrequire">Comparison with SSLRequire</a></li>
-</ul><h3>See also</h3><ul class="seealso"><li><code class="directive"><a href="./mod/core.html#if"><If></a></code></li><li><code class="directive"><a href="./mod/core.html#elseif"><ElseIf></a></code></li><li><code class="directive"><a href="./mod/core.html#else"><Else></a></code></li><li><code class="directive"><a href="./mod/mod_rewrite.html#rewritecond">RewriteCond</a></code></li><li><code class="directive"><a href="./mod/mod_setenvif.html#setenvifexpr">SetEnvIfExpr</a></code></li><li><code class="directive"><a href="./mod/mod_headers.html#header">Header</a></code></li><li><code class="directive"><a href="./mod/mod_headers.html#requestheader">RequestHeader</a></code></li><li><code class="directive"><a href="./mod/mod_filter.html#filterprovider">FilterProvider</a></code></li><li><a href="mod/mod_authz_core.html#reqexpr">Require expr</a></li><li><code class="directive"><a href="./mod/mod_ssl.html#sslrequire">SSLRequire</a></code></li><li><code class="directive"><a href="./mod/mod_log_debug.html#logmessage">LogMessage</a></code></li><li><code class="module"><a href="./mod/mod_include.html">mod_include</a></code></li></ul></div>
+</ul><h3>See also</h3><ul class="seealso"><li><code class="directive"><a href="./mod/core.html#if"><If></a></code></li><li><code class="directive"><a href="./mod/core.html#elseif"><ElseIf></a></code></li><li><code class="directive"><a href="./mod/core.html#else"><Else></a></code></li><li><code class="directive"><a href="./mod/mod_rewrite.html#rewritecond">RewriteCond</a></code></li><li><code class="directive"><a href="./mod/mod_setenvif.html#setenvifexpr">SetEnvIfExpr</a></code></li><li><code class="directive"><a href="./mod/mod_headers.html#header">Header</a></code></li><li><code class="directive"><a href="./mod/mod_headers.html#requestheader">RequestHeader</a></code></li><li><code class="directive"><a href="./mod/mod_filter.html#filterprovider">FilterProvider</a></code></li><li><a href="mod/mod_authz_core.html#reqexpr">Require expr</a></li><li><code class="directive"><a href="./mod/mod_ssl.html#sslrequire">SSLRequire</a></code></li><li><code class="directive"><a href="./mod/mod_log_debug.html#logmessage">LogMessage</a></code></li><li><code class="module"><a href="./mod/mod_include.html">mod_include</a></code></li></ul><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
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<div class="section">
<h2><a name="grammar" id="grammar">Grammar in Backus-Naur Form notation</a></h2>
<p><a href="http://en.wikipedia.org/wiki/Backus%E2%80%93Naur_Form">Backus-Naur Form</a> (BNF) is a notation
technique for context-free grammars, often used to describe the syntax of languages used in computing.
+ In most cases, expressions are used to express boolean values.
+ For these, the starting boint in the BNF is <code>expr</code>. However, a few directives
+ like <code class="directive"><a href="./mod/mod_log_debug.html#logmessage">LogMessage</a></code> accept expressions
+ that evaluate to a string value. For those, the starting boint in the BNF is <code>string</code>.
</p>
<blockquote>
<pre>
<code>%{REMOTE_USER}</code> will not be set in this case.</p>
<p>The following variables provide the values of the named HTTP request
- headers. The values of other headers can be obtained witht the
- <code>req</code> <a href="#functions">function</a>.</p>
+ headers. The values of other headers can be obtained with the
+ <code>req</code> <a href="#functions">function</a>. Using these
+ variables may cause the header name to 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>
+ <a href="#functions">function</a> may be used to circumvent this
+ behavior.</p>
<table class="bordered"><tr class="header"><th>Name</th></tr>
<tr><td><code>HTTP_ACCEPT</code></td></tr>
<td>The <code class="directive"><a href="./mod/core.html#serveradmin">ServerAdmin</a></code> of
the current vhost</td></tr>
<tr><td><code>SERVER_PROTOCOL</code></td>
- <td>The protocol used by the request</td></tr>
-<tr class="odd"><td><code>DOCUMENT_ROOT</code></td>
+ <td>The protocol used by the request (e.g. HTTP/1.1). In some types of
+ internal subrequests, this variable has the value
+ <code>INCLUDED</code>.</td></tr>
+<tr class="odd"><td><code>SERVER_PROTOCOL_VERSION</code></td>
+ <td>A number that encodes the HTTP version of the request:
+ <code>1000 * major + minor</code>. For example, <code>1001</code>
+ corresponds to HTTP/1.1 and <code>9</code> corresponds
+ to HTTP/0.9</td></tr>
+<tr><td><code>SERVER_PROTOCOL_VERSION_MAJOR</code></td>
+ <td>The major version part of the HTTP version of the request,
+ e.g. <code>1</code> for HTTP/1.0</td></tr>
+<tr class="odd"><td><code>SERVER_PROTOCOL_VERSION_MINOR</code></td>
+ <td>The minor version part of the HTTP version of the request,
+ e.g. <code>0</code> for HTTP/1.0</td></tr>
+<tr><td><code>DOCUMENT_ROOT</code></td>
<td>The <code class="directive"><a href="./mod/core.html#documentroot">DocumentRoot</a></code> of
the current vhost</td></tr>
-<tr><td><code>AUTH_TYPE</code></td>
+<tr class="odd"><td><code>AUTH_TYPE</code></td>
<td>The configured <code class="directive"><a href="./mod/mod_authn_core.html#authtype">AuthType</a></code>
(e.g. "<code>basic</code>")</td></tr>
-<tr class="odd"><td><code>CONTENT_TYPE</code></td>
+<tr><td><code>CONTENT_TYPE</code></td>
<td>The content type of the response</td></tr>
-<tr><td><code>HANDLER</code></td>
+<tr class="odd"><td><code>HANDLER</code></td>
<td>The name of the <a href="handler.html">handler</a> creating
the response</td></tr>
-<tr class="odd"><td><code>HTTPS</code></td>
+<tr><td><code>HTTPS</code></td>
<td>"<code>on</code>" if the request uses https,
"<code>off</code>" otherwise</td></tr>
-<tr><td><code>IPV6</code></td>
+<tr class="odd"><td><code>IPV6</code></td>
<td>"<code>on</code>" if the connection uses IPv6,
"<code>off</code>" otherwise</td></tr>
-<tr class="odd"><td><code>REQUEST_STATUS</code></td>
+<tr><td><code>REQUEST_STATUS</code></td>
<td>The HTTP error status of the request</td></tr>
-<tr><td><code>REQUEST_LOG_ID</code></td>
+<tr class="odd"><td><code>REQUEST_LOG_ID</code></td>
<td>The error log id of the request (see
<code class="directive"><a href="./mod/core.html#errorlogformat">ErrorLogFormat</a></code>)</td></tr>
-<tr class="odd"><td><code>CONN_LOG_ID</code></td>
+<tr><td><code>CONN_LOG_ID</code></td>
<td>The error log id of the connection (see
<code class="directive"><a href="./mod/core.html#errorlogformat">ErrorLogFormat</a></code>)</td></tr>
-<tr><td><code>CONN_REMOTE_ADDR</code></td>
+<tr class="odd"><td><code>CONN_REMOTE_ADDR</code></td>
<td>The peer IP address of the connection (see the
<code class="module"><a href="./mod/mod_remoteip.html">mod_remoteip</a></code> module)</td></tr>
</table>
<table class="bordered"><tr class="header"><th>Name</th><th>Description</th><th>Restricted</th></tr>
<tr><td><code>req</code>, <code>http</code></td>
- <td>Get HTTP request header</td><td /></tr>
-<tr class="odd"><td><code>resp</code></td>
+ <td>Get HTTP request header; header names may be added to the Vary
+ header, see below</td><td /></tr>
+<tr class="odd"><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 /></tr>
+<tr><td><code>resp</code></td>
<td>Get HTTP response header</td><td /></tr>
-<tr><td><code>reqenv</code></td>
+<tr class="odd"><td><code>reqenv</code></td>
<td>Lookup request environment variable</td><td /></tr>
-<tr class="odd"><td><code>osenv</code></td>
+<tr><td><code>osenv</code></td>
<td>Lookup operating system environment variable</td><td /></tr>
-<tr><td><code>note</code></td>
+<tr class="odd"><td><code>note</code></td>
<td>Lookup request note</td><td /></tr>
-<tr class="odd"><td><code>env</code></td>
+<tr><td><code>env</code></td>
<td>Return first match of <code>note</code>, <code>reqenv</code>,
<code>osenv</code></td><td /></tr>
-<tr><td><code>tolower</code></td>
+<tr class="odd"><td><code>tolower</code></td>
<td>Convert string to lower case</td><td /></tr>
-<tr class="odd"><td><code>toupper</code></td>
+<tr><td><code>toupper</code></td>
<td>Convert string to uppser case</td><td /></tr>
-<tr><td><code>escape</code></td>
+<tr class="odd"><td><code>escape</code></td>
<td>Escape special characters in %hex encoding</td><td /></tr>
-<tr class="odd"><td><code>unescape</code></td>
+<tr><td><code>unescape</code></td>
<td>Unescape %hex encoded string, leaving encoded slashes alone;
return empty string if %00 is found</td><td /></tr>
-<tr><td><code>file</code></td>
+<tr class="odd"><td><code>file</code></td>
<td>Read contents from a file</td><td>yes</td></tr>
-<tr class="odd"><td><code>filesize</code></td>
+<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 <code class="module"><a href="./mod/mod_include.html">mod_include</a></code>.</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.
<p>The following examples show how expressions might be used to evaluate requests:</p>
- <div class="example"><p><code>
- # Compare the host name to example.com and redirect to www.example.com if it matches<br />
- <If "%{HTTP_HOST} == 'example.com'"><br />
- <span class="indent">
- Redirect permanent / http://www.example.com<br />
- </span>
- </If><br /><br />
- # Force text/plain if requesting a file with the query string contains 'forcetext'<br />
- <If "%{QUERY_STRING} =~ /forcetext/"><br />
- <span class="indent">
- ForceType text/plain<br />
- </span>
- </If><br /><br />
- # Only allow access to this content during business hours<br />
- <Directory "/foo/bar/business"><br />
- <span class="indent">
- Require expr %{TIME_HOUR} >= 9 && %{TIME_HOUR} <= 17 <br />
- </span>
- </Directory>
- </code></p></div>
+ <pre class="prettyprint lang-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>
+ </pre>
+
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<h2><a name="other" id="other">Other</a></h2>
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<p><span>Available Languages: </span><a href="./en/expr.html" title="English"> en </a> |
<a href="./fr/expr.html" hreflang="fr" rel="alternate" title="Français"> fr </a></p>
-</div><div id="footer">
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+</div><div class="top"><a href="#page-header"><img src="./images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed again by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Freenode, or sent to our <a href="http://httpd.apache.org/lists.html">mailing lists</a>.</div>
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