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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-08 19:09:22 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-08 19:09:22 +0000
commit2faa747e2303ee774a4b4aace961188e950e185a (patch)
tree604e79c7481956ce48f458e3546eaf1090b3ffff /docs/manual/mod/mod_include.html.en
parentInitial commit. (diff)
downloadapache2-2faa747e2303ee774a4b4aace961188e950e185a.tar.xz
apache2-2faa747e2303ee774a4b4aace961188e950e185a.zip
Adding upstream version 2.4.58.upstream/2.4.58
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head>
+<meta content="text/html; charset=UTF-8" http-equiv="Content-Type" />
+<!--
+ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+ This file is generated from xml source: DO NOT EDIT
+ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+ -->
+<title>mod_include - Apache HTTP Server Version 2.4</title>
+<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
+<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
+<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="../style/css/prettify.css" />
+<script src="../style/scripts/prettify.min.js" type="text/javascript">
+</script>
+
+<link href="../images/favicon.ico" rel="shortcut icon" /></head>
+<body>
+<div id="page-header">
+<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
+<p class="apache">Apache HTTP Server Version 2.4</p>
+<img alt="" src="../images/feather.png" /></div>
+<div class="up"><a href="./"><img title="&lt;-" alt="&lt;-" src="../images/left.gif" /></a></div>
+<div id="path">
+<a href="http://www.apache.org/">Apache</a> &gt; <a href="http://httpd.apache.org/">HTTP Server</a> &gt; <a href="http://httpd.apache.org/docs/">Documentation</a> &gt; <a href="../">Version 2.4</a> &gt; <a href="./">Modules</a></div>
+<div id="page-content">
+<div id="preamble"><h1>Apache Module mod_include</h1>
+<div class="toplang">
+<p><span>Available Languages: </span><a href="../en/mod/mod_include.html" title="English">&nbsp;en&nbsp;</a> |
+<a href="../fr/mod/mod_include.html" hreflang="fr" rel="alternate" title="Français">&nbsp;fr&nbsp;</a> |
+<a href="../ja/mod/mod_include.html" hreflang="ja" rel="alternate" title="Japanese">&nbsp;ja&nbsp;</a></p>
+</div>
+<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Server-parsed html documents (Server Side Includes)</td></tr>
+<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Base</td></tr>
+<tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>include_module</td></tr>
+<tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_include.c</td></tr></table>
+<h3>Summary</h3>
+
+ <p>This module provides a filter which will process files
+ before they are sent to the client. The processing is
+ controlled by specially formatted SGML comments, referred to as
+ <dfn>elements</dfn>. These elements allow conditional text, the
+ inclusion of other files or programs, as well as the setting and
+ printing of environment variables.</p>
+</div>
+<div id="quickview"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><h3>Topics</h3>
+<ul id="topics">
+<li><img alt="" src="../images/down.gif" /> <a href="#enabling">Enabling Server-Side Includes</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#pathinfo">PATH_INFO with Server Side Includes</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#elements">Available Elements</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#includevars">Include Variables</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#substitution">Variable Substitution</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#flowctrl">Flow Control Elements</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#legacyexpr">Legacy expression syntax</a></li>
+</ul><h3 class="directives">Directives</h3>
+<ul id="toc">
+<li><img alt="" src="../images/down.gif" /> <a href="#ssiendtag">SSIEndTag</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#ssierrormsg">SSIErrorMsg</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#ssietag">SSIETag</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#ssilastmodified">SSILastModified</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#ssilegacyexprparser">SSILegacyExprParser</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#ssistarttag">SSIStartTag</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#ssitimeformat">SSITimeFormat</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#ssiundefinedecho">SSIUndefinedEcho</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#xbithack">XBitHack</a></li>
+</ul>
+<h3>Bugfix checklist</h3><ul class="seealso"><li><a href="https://www.apache.org/dist/httpd/CHANGES_2.4">httpd changelog</a></li><li><a href="https://bz.apache.org/bugzilla/buglist.cgi?bug_status=__open__&amp;list_id=144532&amp;product=Apache%20httpd-2&amp;query_format=specific&amp;order=changeddate%20DESC%2Cpriority%2Cbug_severity&amp;component=mod_include">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&amp;component=mod_include">Report a bug</a></li></ul><h3>See also</h3>
+<ul class="seealso">
+<li><code class="directive"><a href="../mod/core.html#options">Options</a></code></li>
+<li><code class="directive"><a href="../mod/core.html#acceptpathinfo">AcceptPathInfo</a></code></li>
+<li><a href="../filter.html">Filters</a></li>
+<li><a href="../howto/ssi.html">SSI Tutorial</a></li>
+<li><a href="#comments_section">Comments</a></li></ul></div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="enabling" id="enabling">Enabling Server-Side Includes</a></h2>
+
+
+ <p>Server Side Includes are implemented by the
+ <code>INCLUDES</code> <a href="../filter.html">filter</a>. If
+ documents containing server-side include directives are given
+ the extension .shtml, the following directives will make Apache
+ parse them and assign the resulting document the mime type of
+ <code>text/html</code>:</p>
+
+ <pre class="prettyprint lang-config">AddType text/html .shtml
+AddOutputFilter INCLUDES .shtml</pre>
+
+
+ <p>The following directive must be given for the directories
+ containing the shtml files (typically in a
+ <code class="directive"><a href="../mod/core.html#directory">&lt;Directory&gt;</a></code> section,
+ but this directive is also valid in <code>.htaccess</code> files if
+ <code class="directive"><a href="../mod/core.html#allowoverride">AllowOverride</a></code> <code>Options</code>
+ is set):</p>
+
+ <pre class="prettyprint lang-config">Options +Includes</pre>
+
+
+ <p>For backwards compatibility, the <code>server-parsed</code>
+ <a href="../handler.html">handler</a> also activates the
+ INCLUDES filter. As well, Apache will activate the INCLUDES
+ filter for any document with mime type
+ <code>text/x-server-parsed-html</code> or
+ <code>text/x-server-parsed-html3</code> (and the resulting
+ output will have the mime type <code>text/html</code>).</p>
+
+ <p>For more information, see our <a href="../howto/ssi.html">Tutorial on Server Side Includes</a>.</p>
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="pathinfo" id="pathinfo">PATH_INFO with Server Side Includes</a></h2>
+
+
+ <p>Files processed for server-side includes no longer accept
+ requests with <code>PATH_INFO</code> (trailing pathname information)
+ by default. You can use the <code class="directive"><a href="../mod/core.html#acceptpathinfo">AcceptPathInfo</a></code> directive to
+ configure the server to accept requests with <code>PATH_INFO</code>.</p>
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="elements" id="elements">Available Elements</a></h2>
+ <p>The document is parsed as an HTML document, with special
+ commands embedded as SGML comments. A command has the syntax: </p>
+
+ <div class="example"><p><code>
+ &lt;!--#<var>element</var> <var>attribute</var>=<var>value</var>
+ <var>attribute</var>=<var>value</var> ... --&gt;
+ </code></p></div>
+
+ <p>The value will often be enclosed in double quotes, but single
+ quotes (<code>'</code>) and backticks (<code>`</code>) are also
+ possible. Many commands only allow a single attribute-value pair.
+ Note that the comment terminator (<code>--&gt;</code>) should be
+ preceded by whitespace to ensure that it isn't considered part of
+ an SSI token. Note that the leading <code>&lt;!--#</code> is <em>one</em>
+ token and may not contain any whitespaces.</p>
+
+ <p>The allowed elements are listed in the following table:</p>
+
+ <table class="bordered">
+ <tr><th>Element</th><th>Description</th></tr>
+ <tr><td><code><a href="#element.comment">comment</a></code></td>
+ <td>SSI comment</td></tr>
+ <tr><td><code><a href="#element.config">config</a></code></td>
+ <td>configure output formats</td></tr>
+ <tr><td><code><a href="#element.echo">echo</a></code></td>
+ <td>print variables</td></tr>
+ <tr><td><code><a href="#element.exec">exec</a></code></td>
+ <td>execute external programs</td></tr>
+ <tr><td><code><a href="#element.fsize">fsize</a></code></td>
+ <td>print size of a file</td></tr>
+ <tr><td><code><a href="#element.flastmod">flastmod</a></code></td>
+ <td>print last modification time of a file</td></tr>
+ <tr><td><code><a href="#element.include">include</a></code></td>
+ <td>include a file</td></tr>
+ <tr><td><code><a href="#element.printenv">printenv</a></code></td>
+ <td>print all available variables</td></tr>
+ <tr><td><code><a href="#element.set">set</a></code></td>
+ <td>set a value of a variable</td></tr>
+ </table>
+
+ <p>SSI elements may be defined by modules other than
+ <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>. In fact, the <code><a href="#element.exec">exec</a></code> element is provided by
+ <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code>, and will only be available if this
+ module is loaded.</p>
+
+ <h3><a name="element.comment" id="element.comment">The comment Element</a></h3>
+ <p>This command doesn't output anything. Its only use is to
+ add comments within a file. These comments are not printed.</p>
+
+ <p>This syntax is available in version 2.4.21 and later.</p>
+
+ <div class="example"><p><code>
+ &lt;!--#comment Blah Blah Blah --&gt;<br />
+ &nbsp;&nbsp;&nbsp;or<br />
+ &lt;!--#comment text="Blah Blah Blah" --&gt;
+ </code></p></div>
+
+
+ <h3><a name="element.config" id="element.config">The config Element</a></h3>
+ <p>This command controls various aspects of the parsing. The
+ valid attributes are:</p>
+
+ <dl>
+ <dt><code>echomsg</code> (<em>Apache 2.1 and later</em>)</dt>
+ <dd><p>The value is a message that is sent back to the
+ client if the <code><a href="#element.echo">echo</a></code> element
+ attempts to echo an undefined variable. This overrides any <code class="directive"><a href="#ssiundefinedecho">SSIUndefinedEcho</a></code> directives.</p>
+
+ <div class="example"><p><code>
+ &lt;!--#config echomsg="[Value Undefined]" --&gt;
+ </code></p></div>
+ </dd>
+
+ <dt><code>errmsg</code></dt>
+ <dd><p>The value is a message that is sent back to the
+ client if an error occurs while parsing the
+ document. This overrides any <code class="directive"><a href="#ssierrormsg">SSIErrorMsg</a></code> directives.</p>
+
+ <div class="example"><p><code>
+ &lt;!--#config errmsg="[Oops, something broke.]" --&gt;
+ </code></p></div>
+ </dd>
+
+ <dt><code>sizefmt</code></dt>
+ <dd><p>The value sets the format to be used when displaying
+ the size of a file. Valid values are <code>bytes</code>
+ for a count in bytes, or <code>abbrev</code> for a count
+ in Kb or Mb as appropriate, for example a size of 1024 bytes
+ will be printed as "1K".</p>
+
+ <div class="example"><p><code>
+ &lt;!--#config sizefmt="abbrev" --&gt;
+ </code></p></div>
+
+ </dd>
+
+ <dt><code>timefmt</code></dt>
+ <dd><p>The value is a string to be used by the
+ <code>strftime(3)</code> library routine when printing
+ dates.</p>
+
+ <div class="example"><p><code>
+ &lt;!--#config timefmt=""%R, %B %d, %Y"" --&gt;
+ </code></p></div>
+
+ </dd>
+ </dl>
+
+
+ <h3><a name="element.echo" id="element.echo">The echo Element</a></h3>
+ <p>This command prints one of the <a href="#includevars">include
+ variables</a> defined below. If the variable is unset, the result is
+ determined by the <code class="directive"><a href="#ssiundefinedecho">SSIUndefinedEcho</a></code> directive. Any dates printed are
+ subject to the currently configured <code>timefmt</code>.</p>
+
+ <p>Attributes:</p>
+
+ <dl>
+ <dt><code>var</code></dt>
+ <dd>The value is the name of the variable to print.</dd>
+
+ <dt><code>decoding</code></dt>
+ <dd><p>Specifies whether Apache should strip an encoding from
+ the variable before processing the variable further. The default
+ is <code>none</code>, where no decoding will be done. If set to
+ <code>url</code>, then URL decoding (also known as %-encoding;
+ this is appropriate for use within URLs in links, etc.) will be
+ performed. If set to <code>urlencoded</code>,
+ application/x-www-form-urlencoded compatible encoding (found in
+ query strings) will be stripped. If set to <code>base64</code>,
+ base64 will be decoded, and if set to <code>entity</code>, HTML
+ entity encoding will be stripped. Decoding is done prior to any
+ further encoding on the variable. Multiple encodings can be
+ stripped by specifying more than one comma separated encoding.
+ The decoding setting will remain in effect until the next decoding
+ attribute is encountered, or the element ends.</p>
+
+ <p>The <code>decoding</code> attribute must <em>precede</em> the
+ corresponding <code>var</code> attribute to be effective.</p>
+ </dd>
+
+ <dt><code>encoding</code></dt>
+ <dd><p>Specifies how Apache should encode special characters
+ contained in the variable before outputting them. If set
+ to <code>none</code>, no encoding will be done. If set to
+ <code>url</code>, then URL encoding (also known as %-encoding;
+ this is appropriate for use within URLs in links, etc.) will be
+ performed. If set to <code>urlencoded</code>,
+ application/x-www-form-urlencoded compatible encoding will be
+ performed instead, and should be used with query strings. If set
+ to <code>base64</code>, base64 encoding will be performed. At
+ the start of an <code>echo</code> element, the default is set to
+ <code>entity</code>, resulting in entity encoding (which is
+ appropriate in the context of a block-level HTML element,
+ <em>e.g.</em> a paragraph of text). This can be changed by adding
+ an <code>encoding</code> attribute, which will remain in effect
+ until the next <code>encoding</code> attribute is encountered or
+ the element ends, whichever comes first.</p>
+
+ <p>The <code>encoding</code> attribute must <em>precede</em> the
+ corresponding <code>var</code> attribute to be effective.</p>
+
+ <div class="warning">
+ In order to avoid cross-site scripting issues, you should
+ <em>always</em> encode user supplied data.
+ </div>
+
+ <div class="example"><h3>Example</h3><p><code>
+ &lt;!--#echo encoding="entity" var="QUERY_STRING" --&gt;
+ </code></p></div>
+ </dd>
+ </dl>
+
+
+ <h3><a name="element.exec" id="element.exec">The exec Element</a></h3>
+ <p>The <code>exec</code> command executes a given shell command or
+ CGI script. It requires <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code> to be present
+ in the server. If <code class="directive"><a href="../mod/core.html#options">Options</a></code>
+ <code>IncludesNOEXEC</code> is set, this command is completely
+ disabled. The valid attributes are:</p>
+
+ <dl>
+ <dt><code>cgi</code></dt>
+ <dd><p>The value specifies a (%-encoded) URL-path to
+ the CGI script. If the path does not begin with a slash (/),
+ then it is taken to be relative to the current
+ document. The document referenced by this path is
+ invoked as a CGI script, even if the server would not
+ normally recognize it as such. However, the directory
+ containing the script must be enabled for CGI scripts
+ (with <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>
+ or <code class="directive"><a href="../mod/core.html#options">Options</a></code>
+ <code>ExecCGI</code>).</p>
+
+ <p>The CGI script is given the <code>PATH_INFO</code> and query
+ string (<code>QUERY_STRING</code>) of the original request from the
+ client; these <em>cannot</em> be specified in the URL path. The
+ include variables will be available to the script in addition to
+ the standard <a href="mod_cgi.html">CGI</a> environment.</p>
+
+ <div class="example"><h3>Example</h3><p><code>
+ &lt;!--#exec cgi="/cgi-bin/example.cgi" --&gt;
+ </code></p></div>
+
+ <p>If the script returns a <code>Location:</code> header instead of
+ output, then this will be translated into an HTML anchor.</p>
+
+ <p>The <code><a href="#includevirtual">include virtual</a></code>
+ element should be used in preference to <code>exec cgi</code>. In
+ particular, if you need to pass additional arguments to a CGI program,
+ using the query string, this cannot be done with <code>exec
+ cgi</code>, but can be done with <code>include virtual</code>, as
+ shown here:</p>
+
+ <div class="example"><p><code>
+ &lt;!--#include virtual="/cgi-bin/example.cgi?argument=value" --&gt;
+ </code></p></div>
+ </dd>
+
+ <dt><code>cmd</code></dt>
+ <dd><p>The server will execute the given string using
+ <code>/bin/sh</code>. The <a href="#includevars">include variables</a> are available to the command, in addition
+ to the usual set of CGI variables.</p>
+
+ <p>The use of <code><a href="#includevirtual">#include virtual</a></code> is almost always preferred to using
+ either <code>#exec cgi</code> or <code>#exec cmd</code>. The former
+ (<code>#include virtual</code>) uses the standard Apache sub-request
+ mechanism to include files or scripts. It is much better tested and
+ maintained.</p>
+
+ <p>In addition, on some platforms, like Win32, and on unix when
+ using <a href="../suexec.html">suexec</a>, you cannot pass arguments
+ to a command in an <code>exec</code> directive, or otherwise include
+ spaces in the command. Thus, while the following will work under a
+ non-suexec configuration on unix, it will not produce the desired
+ result under Win32, or when running suexec:</p>
+
+ <div class="example"><p><code>
+ &lt;!--#exec cmd="perl /path/to/perlscript arg1 arg2" --&gt;
+ </code></p></div>
+ </dd>
+ </dl>
+
+
+ <h3><a name="element.fsize" id="element.fsize">The fsize Element</a></h3>
+ <p>This command prints the size of the specified file, subject
+ to the <code>sizefmt</code> format specification. Attributes:</p>
+
+ <dl>
+ <dt><code>file</code></dt>
+ <dd>The value is a path relative to the directory
+ containing the current document being parsed.
+
+ <div class="example"><p><code>
+ This file is &lt;!--#fsize file="mod_include.html" --&gt; bytes.
+ </code></p></div>
+
+ The value of <code>file</code> cannot start with a slash
+ (<code>/</code>), nor can it contain <code>../</code> so as to
+ refer to a file above the current directory or outside of the
+ document root. Attempting to so will result in the error message:
+ <code>The given path was above the root path</code>.
+ </dd>
+
+ <dt><code>virtual</code></dt>
+ <dd>The value is a (%-encoded) URL-path. If it does not begin with
+ a slash (/) then it is taken to be relative to the current document.
+ Note, that this does <em>not</em> print the size of any CGI output,
+ but the size of the CGI script itself.</dd>
+ </dl>
+
+ <div class="example"><p><code>
+ This file is &lt;!--#fsize virtual="/docs/mod/mod_include.html" --&gt; bytes.
+ </code></p></div>
+
+ <p>Note that in many cases these two are exactly the same thing.
+ However, the <code>file</code> attribute doesn't respect URL-space
+ aliases.</p>
+
+
+ <h3><a name="element.flastmod" id="element.flastmod">The flastmod Element</a></h3>
+ <p>This command prints the last modification date of the
+ specified file, subject to the <code>timefmt</code> format
+ specification. The attributes are the same as for the
+ <code><a href="#element.fsize">fsize</a></code> command.</p>
+
+
+ <h3><a name="element.include" id="element.include">The include Element</a></h3>
+ <p>This command inserts the text of another document or file
+ into the parsed file. Any included file is subject to the usual
+ access control. If the directory containing the parsed file has
+ <a href="core.html#options">Options</a>
+ <code>IncludesNOEXEC</code> set, then only documents with a text
+ <a class="glossarylink" href="../glossary.html#mime-type" title="see glossary">MIME-type</a> (<code>text/plain</code>,
+ <code>text/html</code> etc.) will be included. Otherwise CGI
+ scripts are invoked as normal using the complete URL given in
+ the command, including any query string.</p>
+
+ <p>An attribute defines the location of the document, and may
+ appear more than once in an include element; an inclusion is
+ done for each attribute given to the include command in turn.
+ The valid attributes are:</p>
+
+ <dl>
+ <dt><code>file</code></dt>
+ <dd>The value is a path relative to the directory
+ containing the current document being parsed. It cannot
+ contain <code>../</code>, nor can it be an absolute path.
+ Therefore, you cannot include files that are outside of the
+ document root, or above the current document in the directory
+ structure. The <code>virtual</code> attribute should always be
+ used in preference to this one.</dd>
+
+ <dt><code><a id="includevirtual" name="includevirtual">virtual</a></code></dt>
+ <dd><p>The value is a (%-encoded) URL-path. The URL cannot contain a
+ scheme or hostname, only a path and an optional query string. If it
+ does not begin with a slash (/) then it is taken to be relative to the
+ current document.</p>
+
+ <p>A URL is constructed from the attribute, and the output the
+ server would return if the URL were accessed by the client is
+ included in the parsed output. Thus included files can be nested.</p>
+
+ <p>If the specified URL is a CGI program, the program will be
+ executed and its output inserted in place of the directive in the
+ parsed file. You may include a query string in a CGI url:</p>
+
+ <div class="example"><p><code>
+ &lt;!--#include virtual="/cgi-bin/example.cgi?argument=value" --&gt;
+ </code></p></div>
+
+ <p><code>include virtual</code> should be used in preference
+ to <code>exec cgi</code> to include the output of CGI programs
+ into an HTML document.</p>
+
+ <p>If the <code class="directive"><a href="../mod/mod_request.html#keptbodysize">KeptBodySize</a></code>
+ directive is correctly configured and valid for this included
+ file, attempts to POST requests to the enclosing HTML document
+ will be passed through to subrequests as POST requests as well.
+ Without the directive, all subrequests are processed as GET
+ requests.</p>
+
+ </dd>
+
+ <dt><code>onerror</code></dt>
+ <dd><p>The value is a (%-encoded) URL-path which is shown should a
+ previous attempt to include a file or virtual attribute failed.
+ To be effective, this attribute must be specified after the
+ file or virtual attributes being covered. If the attempt to
+ include the onerror path fails, or if onerror is not specified, the
+ default error message will be included.</p>
+
+ <div class="example"><p><code>
+ # Simple example<br />
+ &lt;!--#include virtual="/not-exist.html" onerror="/error.html" --&gt;
+ </code></p></div>
+
+ <div class="example"><p><code>
+ # Dedicated onerror paths<br />
+ &lt;!--#include virtual="/path-a.html" onerror="/error-a.html" virtual="/path-b.html" onerror="/error-b.html" --&gt;
+ </code></p></div>
+
+ </dd>
+ </dl>
+
+
+ <h3><a name="element.printenv" id="element.printenv">The printenv Element</a></h3>
+ <p>This prints out a plain text listing of all existing variables and
+ their values. Special characters are entity encoded (see the <code><a href="#element.echo">echo</a></code> element for details)
+ before being output. There are no attributes.</p>
+
+ <div class="example"><h3>Example</h3><p><code>
+ &lt;pre&gt;
+ &lt;!--#printenv --&gt;
+ &lt;/pre&gt;
+ </code></p></div>
+
+
+ <h3><a name="element.set" id="element.set">The set Element</a></h3>
+ <p>This sets the value of a variable. Attributes:</p>
+
+ <dl>
+ <dt><code>var</code></dt>
+ <dd>The name of the variable to set.</dd>
+
+ <dt><code>value</code></dt>
+ <dd>The value to give a variable.</dd>
+
+ <dt><code>decoding</code></dt>
+ <dd><p>Specifies whether Apache should strip an encoding from
+ the variable before processing the variable further. The default
+ is <code>none</code>, where no decoding will be done. If set to
+ <code>url</code>, <code>urlencoded</code>, <code>base64</code>
+ or <code>entity</code>, URL decoding,
+ application/x-www-form-urlencoded decoding, base64 decoding or HTML
+ entity decoding will be performed respectively. More than one
+ decoding can be specified by separating with commas. The decoding
+ setting will remain in effect until the next decoding attribute
+ is encountered, or the element ends. The <code>decoding</code>
+ attribute must <em>precede</em> the corresponding
+ <code>var</code> attribute to be effective.</p>
+ </dd>
+
+ <dt><code>encoding</code></dt>
+ <dd><p>Specifies how Apache should encode special characters
+ contained in the variable before setting them. The default is
+ <code>none</code>, where no encoding will be done. If set to
+ <code>url</code>, <code>urlencoding</code>, <code>base64</code>
+ or <code>entity</code>, URL encoding,
+ application/x-www-form-urlencoded encoding, base64 encoding or
+ HTML entity encoding will be performed respectively. More than
+ one encoding can be specified by separating with commas. The
+ encoding setting will remain in effect until the next encoding
+ attribute is encountered, or the element ends. The
+ <code>encoding</code> attribute must <em>precede</em> the
+ corresponding <code>var</code> attribute to be effective.
+ Encodings are applied after all decodings have been
+ stripped.</p>
+ </dd>
+ </dl>
+
+ <div class="example"><h3>Example</h3><p><code>
+ &lt;!--#set var="category" value="help" --&gt;
+ </code></p></div>
+
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="includevars" id="includevars">Include Variables</a></h2>
+
+
+ <p>In addition to the variables in the standard CGI environment,
+ these are available for the <code>echo</code> command, for
+ <code>if</code> and <code>elif</code>, and to any program
+ invoked by the document.</p>
+
+ <dl>
+ <dt><code>DATE_GMT</code></dt>
+ <dd>The current date in Greenwich Mean Time.</dd>
+
+ <dt><code>DATE_LOCAL</code></dt>
+ <dd>The current date in the local time zone.</dd>
+
+ <dt><code>DOCUMENT_ARGS</code></dt>
+ <dd>This variable contains the query string of the active SSI
+ document, or the empty string if a query string is not
+ included. For subrequests invoked through the
+ <code>include</code> SSI directive, <code>QUERY_STRING</code>
+ will represent the query string of the subrequest and
+ <code>DOCUMENT_ARGS</code> will represent the query string of
+ the SSI document. (Available in Apache HTTP Server 2.4.19 and
+ later.)</dd>
+
+ <dt><code>DOCUMENT_NAME</code></dt>
+ <dd>The filename (excluding directories) of the document
+ requested by the user.</dd>
+
+ <dt><code>DOCUMENT_PATH_INFO</code></dt>
+ <dd>The trailing pathname information. See directive <code class="directive"><a href="../mod/core.html#acceptpathinfo">AcceptPathInfo</a></code> for more information
+ about <code>PATH_INFO</code>.</dd>
+
+ <dt><code>DOCUMENT_URI</code></dt>
+ <dd>The (%-decoded) URL path of the document requested by the
+ user. Note that in the case of nested include files, this is
+ <em>not</em> the URL for the current document. Note also that
+ if the URL is modified internally (e.g. by an <code class="directive"><a href="../mod/mod_alias.html#alias">alias</a></code> or <code class="directive"><a href="../mod/mod_dir.html#directoryindex">directoryindex</a></code>), the modified
+ URL is shown.</dd>
+
+ <dt><code>LAST_MODIFIED</code></dt>
+ <dd>The last modification date of the document requested by
+ the user.</dd>
+
+ <dt><code>QUERY_STRING_UNESCAPED</code></dt>
+ <dd>If a query string is present in the request for the active
+ SSI document, this variable contains the (%-decoded) query
+ string, which is <em>escaped</em> for shell usage (special
+ characters like <code>&amp;</code> etc. are preceded by
+ backslashes). It is not set if a query string is not
+ present. Use <code>DOCUMENT_ARGS</code> if shell escaping
+ is not desired.</dd>
+
+ <dt><code>USER_NAME</code></dt>
+ <dd>The user name of the owner of the file.</dd>
+ </dl>
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="substitution" id="substitution">Variable Substitution</a></h2>
+
+ <p>Variable substitution is done within quoted strings in most
+ cases where they may reasonably occur as an argument to an SSI
+ directive. This includes the <code>config</code>,
+ <code>exec</code>, <code>flastmod</code>, <code>fsize</code>,
+ <code>include</code>, <code>echo</code>, and <code>set</code>
+ directives. If <code class="directive"><a href="#ssilegacyexprparser">SSILegacyExprParser</a></code> is set to <code>on</code>,
+ substitution also occurs in the arguments to conditional operators.
+ You can insert a literal dollar sign into the string using backslash
+ quoting:</p>
+
+ <div class="example"><p><code>
+ &lt;!--#set var="cur" value="\$test" --&gt;
+ </code></p></div>
+
+ <p>If a variable reference needs to be substituted in the
+ middle of a character sequence that might otherwise be
+ considered a valid identifier in its own right, it can be
+ disambiguated by enclosing the reference in braces,
+ <em>a la</em> shell substitution:</p>
+
+ <div class="example"><p><code>
+ &lt;!--#set var="Zed" value="${REMOTE_HOST}_${REQUEST_METHOD}" --&gt;
+ </code></p></div>
+
+ <p>This will result in the <code>Zed</code> variable being set
+ to "<code>X_Y</code>" if <code>REMOTE_HOST</code> is
+ "<code>X</code>" and <code>REQUEST_METHOD</code> is
+ "<code>Y</code>".</p>
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="flowctrl" id="flowctrl">Flow Control Elements</a></h2>
+
+
+ <p>The basic flow control elements are:</p>
+
+ <div class="example"><p><code>
+ &lt;!--#if expr="<var>test_condition</var>" --&gt;<br />
+ &lt;!--#elif expr="<var>test_condition</var>" --&gt;<br />
+ &lt;!--#else --&gt;<br />
+ &lt;!--#endif --&gt;
+ </code></p></div>
+
+ <p>The <code>if</code> element works like an if statement in a
+ programming language. The test condition is evaluated and if
+ the result is true, then the text until the next <code>elif</code>,
+ <code>else</code> or <code>endif</code> element is included in the
+ output stream.</p>
+
+ <p>The <code>elif</code> or <code>else</code> statements are used
+ to put text into the output stream if the original
+ <var>test_condition</var> was false. These elements are optional.</p>
+
+ <p>The <code>endif</code> element ends the <code>if</code> element
+ and is required.</p>
+
+ <p><var>test_condition</var> is a boolean expression which follows the
+ <a href="../expr.html">ap_expr</a> syntax. The syntax can be changed
+ to be compatible with Apache HTTPD 2.2.x using <code class="directive"><a href="#ssilegacyexprparser">SSILegacyExprParser</a></code>.</p>
+
+ <p>The SSI variables set with the <code>var</code> element are exported
+ into the request environment and can be accessed with the
+ <code>reqenv</code> function. As a short-cut, the function name
+ <code>v</code> is also available inside <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>.</p>
+
+ <p>The below example will print "from local net" if client IP address
+ belongs to the 10.0.0.0/8 subnet.</p>
+
+ <div class="example"><p><code>
+ &lt;!--#if expr='-R "10.0.0.0/8"' --&gt;<br />
+ <span class="indent">
+ from local net<br />
+ </span>
+ &lt;!--#else --&gt;<br />
+ <span class="indent">
+ from somewhere else<br />
+ </span>
+ &lt;!--#endif --&gt;
+ </code></p></div>
+
+ <p>The below example will print "foo is bar" if the variable
+ <code>foo</code> is set to the value "bar".</p>
+
+ <div class="example"><p><code>
+ &lt;!--#if expr='v("foo") = "bar"' --&gt;<br />
+ <span class="indent">
+ foo is bar<br />
+ </span>
+ &lt;!--#endif --&gt;
+ </code></p></div>
+
+ <div class="note"><h3>Reference Documentation</h3>
+ <p>See also: <a href="../expr.html">Expressions in Apache HTTP Server</a>,
+ for a complete reference and examples. The <em>restricted</em> functions
+ are not available inside <code class="module"><a href="../mod/mod_include.html">mod_include</a></code></p>
+ </div>
+</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="legacyexpr" id="legacyexpr">Legacy expression syntax</a></h2>
+
+
+ <p>This section describes the syntax of the <code>#if expr</code>
+ element if <code class="directive"><a href="#ssilegacyexprparser">SSILegacyExprParser</a></code>
+ is set to <code>on</code>.</p>
+
+ <dl>
+ <dt><code><var>string</var></code></dt>
+ <dd>true if <var>string</var> is not empty</dd>
+
+ <dt><code><var>-A string</var></code></dt>
+ <dd><p>true if the URL represented by the string is accessible by
+ configuration, false otherwise. This is useful where content on a
+ page is to be hidden from users who are not authorized to view the
+ URL, such as a link to that URL. Note that the URL is only tested
+ for whether access would be granted, not whether the URL exists.</p>
+
+ <div class="example"><h3>Example</h3><p><code>
+ &lt;!--#if expr="-A /private" --&gt;<br />
+ <span class="indent">
+ Click &lt;a href="/private"&gt;here&lt;/a&gt; to access private
+ information.<br />
+ </span>
+ &lt;!--#endif --&gt;
+ </code></p></div>
+ </dd>
+
+ <dt><code><var>string1</var> = <var>string2</var><br />
+ <var>string1</var> == <var>string2</var><br />
+ <var>string1</var> != <var>string2</var></code></dt>
+
+ <dd><p>Compare <var>string1</var> with <var>string2</var>. If
+ <var>string2</var> has the form <code>/<var>string2</var>/</code>
+ then it is treated as a regular expression. Regular expressions are
+ implemented by the <a href="http://www.pcre.org">PCRE</a> engine and
+ have the same syntax as those in <a href="http://www.perl.com">perl
+ 5</a>. Note that <code>==</code> is just an alias for <code>=</code>
+ and behaves exactly the same way.</p>
+
+ <p>If you are matching positive (<code>=</code> or <code>==</code>), you
+ can capture grouped parts of the regular expression. The captured parts
+ are stored in the special variables <code>$1</code> ..
+ <code>$9</code>. The whole string matched by the regular expression is
+ stored in the special variable <code>$0</code></p>
+
+ <div class="example"><h3>Example</h3><p><code>
+ &lt;!--#if expr="$QUERY_STRING = /^sid=([a-zA-Z0-9]+)/" --&gt;<br />
+ <span class="indent">
+ &lt;!--#set var="session" value="$1" --&gt;<br />
+ </span>
+ &lt;!--#endif --&gt;
+ </code></p></div>
+ </dd>
+
+ <dt><code><var>string1</var> &lt; <var>string2</var><br />
+ <var>string1</var> &lt;= <var>string2</var><br />
+ <var>string1</var> &gt; <var>string2</var><br />
+ <var>string1</var> &gt;= <var>string2</var></code></dt>
+
+ <dd>Compare <var>string1</var> with <var>string2</var>. Note, that
+ strings are compared <em>literally</em> (using
+ <code>strcmp(3)</code>). Therefore the string "100" is less than
+ "20".</dd>
+
+ <dt><code>( <var>test_condition</var> )</code></dt>
+ <dd>true if <var>test_condition</var> is true</dd>
+
+ <dt><code>! <var>test_condition</var></code></dt>
+ <dd>true if <var>test_condition</var> is false</dd>
+
+ <dt><code><var>test_condition1</var> &amp;&amp;
+ <var>test_condition2</var></code></dt>
+ <dd>true if both <var>test_condition1</var> and
+ <var>test_condition2</var> are true</dd>
+
+ <dt><code><var>test_condition1</var> ||
+ <var>test_condition2</var></code></dt>
+ <dd>true if either <var>test_condition1</var> or
+ <var>test_condition2</var> is true</dd>
+ </dl>
+
+ <p>"<code>=</code>" and "<code>!=</code>" bind more tightly than
+ "<code>&amp;&amp;</code>" and "<code>||</code>". "<code>!</code>" binds
+ most tightly. Thus, the following are equivalent:</p>
+
+ <div class="example"><p><code>
+ &lt;!--#if expr="$a = test1 &amp;&amp; $b = test2" --&gt;<br />
+ &lt;!--#if expr="($a = test1) &amp;&amp; ($b = test2)" --&gt;
+ </code></p></div>
+
+ <p>The boolean operators <code>&amp;&amp;</code> and <code>||</code>
+ share the same priority. So if you want to bind such an operator more
+ tightly, you should use parentheses.</p>
+
+ <p>Anything that's not recognized as a variable or an operator
+ is treated as a string. Strings can also be quoted:
+ <code>'string'</code>. Unquoted strings can't contain whitespace
+ (blanks and tabs) because it is used to separate tokens such as
+ variables. If multiple strings are found in a row, they are
+ concatenated using blanks. So,</p>
+
+ <div class="example"><p><code><var>string1</var>&nbsp;&nbsp;&nbsp;&nbsp;<var>string2</var></code> results in <code><var>string1</var>&nbsp;<var>string2</var></code><br />
+ <br />
+ and<br />
+ <br />
+ <code>'<var>string1</var>&nbsp;&nbsp;&nbsp;&nbsp;<var>string2</var>'</code> results in <code><var>string1</var>&nbsp;&nbsp;&nbsp;&nbsp;<var>string2</var></code>.</p></div>
+
+ <div class="note"><h3>Optimization of Boolean Expressions</h3>
+ <p>If the expressions become more complex and slow down processing
+ significantly, you can try to optimize them according to the
+ evaluation rules:</p>
+ <ul>
+ <li>Expressions are evaluated from left to right</li>
+ <li>Binary boolean operators (<code>&amp;&amp;</code> and <code>||</code>)
+ are short circuited wherever possible. In conclusion with the rule
+ above that means, <code class="module"><a href="../mod/mod_include.html">mod_include</a></code> evaluates at first
+ the left expression. If the left result is sufficient to determine
+ the end result, processing stops here. Otherwise it evaluates the
+ right side and computes the end result from both left and right
+ results.</li>
+ <li>Short circuit evaluation is turned off as long as there are regular
+ expressions to deal with. These must be evaluated to fill in the
+ backreference variables (<code>$1</code> .. <code>$9</code>).</li>
+ </ul>
+ <p>If you want to look how a particular expression is handled, you can
+ recompile <code class="module"><a href="../mod/mod_include.html">mod_include</a></code> using the
+ <code>-DDEBUG_INCLUDE</code> compiler option. This inserts for every
+ parsed expression tokenizer information, the parse tree and how it is
+ evaluated into the output sent to the client.</p>
+ </div>
+
+ <div class="note"><h3>Escaping slashes in regex strings</h3>
+ <p>All slashes which are not intended to act as delimiters in your regex must
+ be escaped. This is regardless of their meaning to the regex engine.</p>
+ </div>
+
+</div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="directive-section"><h2><a name="SSIEndTag" id="SSIEndTag">SSIEndTag</a> <a name="ssiendtag" id="ssiendtag">Directive</a></h2>
+<table class="directive">
+<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>String that ends an include element</td></tr>
+<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SSIEndTag <var>tag</var></code></td></tr>
+<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SSIEndTag "--&gt;"</code></td></tr>
+<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
+<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
+<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_include</td></tr>
+</table>
+ <p>This directive changes the string that <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
+ looks for to mark the end of an include element.</p>
+
+ <pre class="prettyprint lang-config">SSIEndTag "%&gt;"</pre>
+
+
+
+<h3>See also</h3>
+<ul>
+<li><code class="directive"><a href="#ssistarttag">SSIStartTag</a></code></li>
+</ul>
+</div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="directive-section"><h2><a name="SSIErrorMsg" id="SSIErrorMsg">SSIErrorMsg</a> <a name="ssierrormsg" id="ssierrormsg">Directive</a></h2>
+<table class="directive">
+<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Error message displayed when there is an SSI
+error</td></tr>
+<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SSIErrorMsg <var>message</var></code></td></tr>
+<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SSIErrorMsg "[an error occurred while processing this
+directive]"</code></td></tr>
+<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
+<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
+<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
+<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_include</td></tr>
+</table>
+ <p>The <code class="directive">SSIErrorMsg</code> directive changes the error
+ message displayed when <code class="module"><a href="../mod/mod_include.html">mod_include</a></code> encounters an
+ error. For production servers you may consider changing the default
+ error message to <code>"&lt;!-- Error --&gt;"</code> so that
+ the message is not presented to the user.</p>
+
+ <p>This directive has the same effect as the <code>&lt;!--#config
+ errmsg=<var>message</var> --&gt;</code> element.</p>
+
+ <pre class="prettyprint lang-config">SSIErrorMsg "&lt;!-- Error --&gt;"</pre>
+
+
+</div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="directive-section"><h2><a name="SSIETag" id="SSIETag">SSIETag</a> <a name="ssietag" id="ssietag">Directive</a></h2>
+<table class="directive">
+<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls whether ETags are generated by the server.</td></tr>
+<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SSIETag on|off</code></td></tr>
+<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SSIETag off</code></td></tr>
+<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
+<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
+<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_include</td></tr>
+<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.2.15 and later.</td></tr>
+</table>
+ <p>Under normal circumstances, a file filtered by <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
+ may contain elements that are either dynamically generated, or that may
+ have changed independently of the original file. As a result, by default
+ the server is asked not to generate an <code>ETag</code> header for the
+ response by adding <code>no-etag</code> to the request notes.</p>
+
+ <p>The <code class="directive">SSIETag</code> directive suppresses this
+ behaviour, and allows the server to generate an <code>ETag</code> header.
+ This can be used to enable caching of the output. Note that a backend server
+ or dynamic content generator may generate an ETag of its own, ignoring
+ <code>no-etag</code>, and this ETag will be passed by
+ <code class="module"><a href="../mod/mod_include.html">mod_include</a></code> regardless of the value of this setting.
+ <code class="directive">SSIETag</code> can take on the following values:</p>
+
+ <dl>
+
+ <dt><code>off</code></dt>
+ <dd><code>no-etag</code> will be added to the request notes, and the server
+ is asked not to generate an ETag. Where a server ignores the value of
+ <code>no-etag</code> and generates an ETag anyway, the ETag will be
+ respected.</dd>
+
+ <dt><code>on</code></dt>
+ <dd>Existing ETags will be respected, and ETags generated by the server will
+ be passed on in the response.</dd>
+
+ </dl>
+
+
+</div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="directive-section"><h2><a name="SSILastModified" id="SSILastModified">SSILastModified</a> <a name="ssilastmodified" id="ssilastmodified">Directive</a></h2>
+<table class="directive">
+<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls whether <code>Last-Modified</code> headers are generated by the
+server.</td></tr>
+<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SSILastModified on|off</code></td></tr>
+<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SSILastModified off</code></td></tr>
+<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
+<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
+<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_include</td></tr>
+<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.2.15 and later.</td></tr>
+</table>
+ <p>Under normal circumstances, a file filtered by <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
+ may contain elements that are either dynamically generated, or that may
+ have changed independently of the original file. As a result, by default
+ the <code>Last-Modified</code> header is stripped from the response.</p>
+
+ <p>The <code class="directive">SSILastModified</code> directive overrides this
+ behaviour, and allows the <code>Last-Modified</code> header to be respected
+ if already present, or set if the header is not already present. This can
+ be used to enable caching of the output. <code class="directive">SSILastModified</code>
+ can take on the following values:</p>
+
+ <dl>
+
+ <dt><code>off</code></dt>
+ <dd>The <code>Last-Modified</code> header will be stripped from responses,
+ unless the <code class="directive"><a href="#xbithack">XBitHack</a></code> directive
+ is set to <code>full</code> as described below.</dd>
+
+ <dt><code>on</code></dt>
+ <dd>The <code>Last-Modified</code> header will be respected if already
+ present in a response, and added to the response if the response is a
+ file and the header is missing. The
+ <code class="directive"><a href="#ssilastmodified">SSILastModified</a></code> directive
+ takes precedence over <code class="directive"><a href="#xbithack">XBitHack</a></code>.</dd>
+
+ </dl>
+
+
+</div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="directive-section"><h2><a name="SSILegacyExprParser" id="SSILegacyExprParser">SSILegacyExprParser</a> <a name="ssilegacyexprparser" id="ssilegacyexprparser">Directive</a></h2>
+<table class="directive">
+<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enable compatibility mode for conditional expressions.</td></tr>
+<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SSILegacyExprParser on|off</code></td></tr>
+<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SSILegacyExprParser off</code></td></tr>
+<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
+<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
+<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_include</td></tr>
+<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.3.13 and later.</td></tr>
+</table>
+ <p>As of version 2.3.13, <code class="module"><a href="../mod/mod_include.html">mod_include</a></code> has switched to the
+ new <a href="../expr.html">ap_expr</a> syntax for conditional expressions
+ in <code>#if</code> flow control elements. This directive allows to
+ switch to the <a href="#legacyexpr">old syntax</a> which is compatible
+ with Apache HTTPD version 2.2.x and earlier.
+ </p>
+
+</div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="directive-section"><h2><a name="SSIStartTag" id="SSIStartTag">SSIStartTag</a> <a name="ssistarttag" id="ssistarttag">Directive</a></h2>
+<table class="directive">
+<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>String that starts an include element</td></tr>
+<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SSIStartTag <var>tag</var></code></td></tr>
+<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SSIStartTag "&lt;!--#"</code></td></tr>
+<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
+<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
+<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_include</td></tr>
+</table>
+ <p>This directive changes the string that <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
+ looks for to mark an include element to process.</p>
+
+ <p>You may want to use this option if you have 2 servers parsing the
+ output of a file each processing different commands (possibly at
+ different times).</p>
+
+ <pre class="prettyprint lang-config">SSIStartTag "&lt;%"
+SSIEndTag "%&gt;"</pre>
+
+
+ <p>The example given above, which also specifies a matching
+ <code class="directive"><a href="#ssiendtag">SSIEndTag</a></code>, will
+ allow you to use SSI directives as shown in the example
+ below:</p>
+
+ <div class="example"><h3>SSI directives with alternate start and end tags</h3><p><code>
+ &lt;%printenv %&gt;
+ </code></p></div>
+
+<h3>See also</h3>
+<ul>
+<li><code class="directive"><a href="#ssiendtag">SSIEndTag</a></code></li>
+</ul>
+</div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="directive-section"><h2><a name="SSITimeFormat" id="SSITimeFormat">SSITimeFormat</a> <a name="ssitimeformat" id="ssitimeformat">Directive</a></h2>
+<table class="directive">
+<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures the format in which date strings are
+displayed</td></tr>
+<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SSITimeFormat <var>formatstring</var></code></td></tr>
+<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SSITimeFormat "%A, %d-%b-%Y %H:%M:%S %Z"</code></td></tr>
+<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
+<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
+<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
+<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_include</td></tr>
+</table>
+<p>This directive changes the format in which date strings are displayed
+ when echoing <code>DATE</code> environment variables. The
+ <var>formatstring</var> is as in <code>strftime(3)</code> from the
+ C standard library.</p>
+
+ <p>This directive has the same effect as the <code>&lt;!--#config
+ timefmt=<var>formatstring</var> --&gt;</code> element.</p>
+
+ <pre class="prettyprint lang-config">SSITimeFormat "%R, %B %d, %Y"</pre>
+
+
+ <p>The above directive would cause times to be displayed in the
+ format "22:26, June 14, 2002".</p>
+
+</div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="directive-section"><h2><a name="SSIUndefinedEcho" id="SSIUndefinedEcho">SSIUndefinedEcho</a> <a name="ssiundefinedecho" id="ssiundefinedecho">Directive</a></h2>
+<table class="directive">
+<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>String displayed when an unset variable is echoed</td></tr>
+<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SSIUndefinedEcho <var>string</var></code></td></tr>
+<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SSIUndefinedEcho "(none)"</code></td></tr>
+<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
+<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
+<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
+<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_include</td></tr>
+</table>
+ <p>This directive changes the string that <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
+ displays when a variable is not set and "echoed".</p>
+
+ <pre class="prettyprint lang-config">SSIUndefinedEcho "&lt;!-- undef --&gt;"</pre>
+
+
+</div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="directive-section"><h2><a name="XBitHack" id="XBitHack">XBitHack</a> <a name="xbithack" id="xbithack">Directive</a></h2>
+<table class="directive">
+<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Parse SSI directives in files with the execute bit
+set</td></tr>
+<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>XBitHack on|off|full</code></td></tr>
+<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>XBitHack off</code></td></tr>
+<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
+<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Options</td></tr>
+<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
+<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_include</td></tr>
+</table>
+ <p>The <code class="directive">XBitHack</code> directive controls the parsing
+ of ordinary html documents. This directive only affects files associated
+ with the <a class="glossarylink" href="../glossary.html#mime-type" title="see glossary">MIME-type</a> <code>text/html</code>. <code class="directive">XBitHack</code> can take on the following values:</p>
+
+ <dl>
+ <dt><code>off</code></dt>
+ <dd>No special treatment of executable files.</dd>
+
+ <dt><code>on</code></dt>
+ <dd>Any <code>text/html</code> file that has the user-execute bit
+ set will be treated as a server-parsed html document.</dd>
+
+ <dt><code>full</code></dt>
+ <dd>As for <code>on</code> but also test the group-execute bit.
+ If it is set, then set the <code>Last-modified</code> date of the
+ returned file to be the last modified time of the file. If
+ it is not set, then no last-modified date is sent. Setting
+ this bit allows clients and proxies to cache the result of
+ the request.
+
+ <div class="note"><h3>Note</h3>
+ <p>You would not want to use the full option, unless you assure the
+ group-execute bit is unset for every SSI script which might <code>#include</code> a CGI or otherwise produces different output on
+ each hit (or could potentially change on subsequent requests).</p>
+
+ <p>The <code class="directive"><a href="#ssilastmodified">SSILastModified</a></code>
+ directive takes precedence over the
+ <code class="directive"><a href="#xbithack">XBitHack</a></code> directive when
+ <code class="directive"><a href="#ssilastmodified">SSILastModified</a></code> is set to
+ <code>on</code>.</p>
+ </div>
+
+ </dd>
+ </dl>
+
+
+</div>
+</div>
+<div class="bottomlang">
+<p><span>Available Languages: </span><a href="../en/mod/mod_include.html" title="English">&nbsp;en&nbsp;</a> |
+<a href="../fr/mod/mod_include.html" hreflang="fr" rel="alternate" title="Français">&nbsp;fr&nbsp;</a> |
+<a href="../ja/mod/mod_include.html" hreflang="ja" rel="alternate" title="Japanese">&nbsp;ja&nbsp;</a></p>
+</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&amp;A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed 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 Libera.chat, or sent to our <a href="https://httpd.apache.org/lists.html">mailing lists</a>.</div>
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+<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div><script type="text/javascript"><!--//--><![CDATA[//><!--
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