path: root/docs/manual/mod/mod_include.xml

<?xml version="1.0"?>
<!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
<?xml-stylesheet type="text/xsl" href="../style/manual.xsl"?>
<modulesynopsis>

<name>mod_include</name>
<description>Server-parsed html documents (Server Side Includes)</description>
<status>Base</status>
<sourcefile>mod_include.c</sourcefile>
<identifier>include_module</identifier>

<summary>

    <p>This module provides a filter which will process files
    before they are sent to the client. The processing is
    controlled by specially formated SGML comments, referred to as
    <em>elements</em>. These elements allow conditional text, the
    inclusion other files or programs, as well as the setting and
    printing of environment variables.</p>

</summary>
    <seealso><directive module="core">Options</directive></seealso>
    <seealso><directive module="core">SetOutputFilter</directive></seealso>
    <seealso><directive module="core">AcceptPathInfo</directive></seealso>

<section id="enabling">
    <title>Enabling Server-Side Includes</title>

    <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>

    <example>
      AddType text/html .shtml<br />
      AddOutputFilter INCLUDES .shtml
    </example>

    <p>The following directive must be given for the directories
    containing the shtml files (typically in a
    <code>&lt;Directory&gt;</code> section, but this directive is
    also valid .htaccess files if <code>AllowOverride
    Options</code> is set):</p>

    <example>
      Options +Includes
    </example>

    <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>
</section>

<section id="basic">
    <title>Basic Elements</title>
    <p>The document is parsed as an HTML document, with special
    commands embedded as SGML comments. A command has the syntax: </p>

    <example>
      <code>&lt;!--#</code><em>element attribute=value
      attribute=value ...</em> <code>--&gt;</code>
    </example>

    <p>The value will often be enclosed in double quotes; 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. </p>

    <p>The allowed elements are:</p>

    <dl>
      <dt><strong>config</strong></dt>

      <dd>
        This command controls various aspects of the parsing. The
        valid attributes are: 

        <dl>
          <dt><strong>errmsg</strong></dt>

          <dd>The value is a message that is sent back to the
          client if an error occurs whilst parsing the
          document.</dd>

          <dt><strong>sizefmt</strong></dt>

          <dd>The value sets the format to be used which 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.</dd>

          <dt><strong>timefmt</strong></dt>

          <dd>The value is a string to be used by the
          <code>strftime(3)</code> library routine when printing
          dates.</dd>
        </dl>
      </dd>

      <dt><strong><a name="echo">echo</a></strong></dt>

      <dd>
        <p>This command prints one of the <a href="#includevars">include
        variables</a>, defined below. If the variable is unset, it
        is printed as <code>(none)</code>. Any dates printed are
        subject to the currently configured <code>timefmt</code>.</p>

        <p>Attributes:</p> 

        <dl>
          <dt><strong>var</strong></dt>

          <dd>The value is the name of the variable to print.</dd>

          <dt><strong>encoding</strong></dt>

          <dd>Specifies how Apache should encode special characters
          contained in the variable before outputting them. If set
          to "none", no encoding will be done. If set to "url",
          then URL encoding (also known as %-encoding; this is
          appropriate for use within URLs in links, etc.) will be
          performed. At the start of an <code>echo</code> element,
          the default is set to "entity", resulting in entity
          encoding (which is appropriate in the context of a
          block-level HTML element, eg. 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. Note that the
          <code>encoding</code> attribute must <em>precede</em> the
          corresponding <code>var</code> attribute to be effective,
          and that only special characters as defined in the
          ISO-8859-1 character encoding will be encoded. This
          encoding process may not have the desired result if a
          different character encoding is in use. Apache 1.3.12 and
          above; previous versions do no encoding.</dd>
        </dl>
      </dd>

      <dt><strong>exec</strong></dt>

      <dd>
        The exec command executes a given shell command or CGI
        script. The IncludesNOEXEC <directive
        module="core">Option</directive> disables this command
        completely. The valid attributes are: 

        <dl>
          <dt><strong>cgi</strong></dt>

          <dd>
            The value specifies a (%-encoded) URL relative path to
            the CGI script. If the path does not begin with a (/),
            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 <directive module="mod_alias">ScriptAlias</directive>
            or the ExecCGI <directive module="core">Option</directive>). 

            <p>The CGI script is given the PATH_INFO and query
            string (QUERY_STRING) of the original request from the
            client; these cannot 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>

            <p>For example:</p>

  <example>&lt;!--#exec cgi="/cgi-bin/example.cgi" --&gt;</example>

            <p>If the script returns a Location: 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>

  <example>
  &lt;!--#include virtual="/cgi-bin/example.cgi?argument=value" --&gt;
  </example>

          </dd>

          <dt><strong>cmd</strong></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
        prefered to using either <code>#exec cgi</code> or <code>#exec
        cmd</code>. The former (<code>#include virtual</code>) used 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 suexec, 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>

   <example>
   &lt;!--#exec cmd="perl /path/to/perlscript arg1 arg2" --&gt;
   </example>

          </dd>
        </dl>
      </dd>

      <dt><strong>fsize</strong></dt>

      <dd>
        This command prints the size of the specified file, subject
        to the <code>sizefmt</code> format specification.
        Attributes: 

        <dl>
          <dt><strong>file</strong></dt>

          <dd>The value is a path relative to the directory
          containing the current document being parsed.</dd>

          <dt><strong>virtual</strong></dt>

          <dd>The value is a (%-encoded) URL-path relative to the
          current document being parsed. If it does not begin with
          a slash (/) then it is taken to be relative to the
          current document.</dd>
        </dl>
      </dd>

      <dt><strong>flastmod</strong></dt>

      <dd>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>fsize</code> command.</dd>

      <dt><strong>include</strong></dt>

      <dd>
        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 the <a href="core.html#options">Option</a>
        IncludesNOEXEC set, and the including the document would
        cause a program to be executed, then it will not be
        included; this prevents the execution of CGI scripts.
        Otherwise CGI scripts are invoked as normal using the
        complete URL given in the command, including any query
        string. 

        <p>An attribute defines the location of the document; the
        inclusion is done for each attribute given to the include
        command. The valid attributes are:</p>

        <dl>
          <dt><strong>file</strong></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><strong><a name="includevirtual">virtual</a></strong></dt>

         <dd>
          <p>The value is a (%-encoded) URL relative to the
          current document being parsed. 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>
     
     <example>
     &lt;!--#include virtual="/cgi-bin/example.cgi?argument=value" --&gt;
     </example>
           
           <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>
          </dd>
        </dl>
      </dd>

      <dt><strong>printenv</strong></dt>

      <dd>
      <p>This prints out a listing of all existing variables and
      their values. Starting with Apache 1.3.12, special characters
      are entity encoded (see the <a
      href="#echo"><code>echo</code></a> element for details)
      before being output. There are no attributes.</p>

      <p>For example:</p>

      <example>
      &lt;!--#printenv --&gt;
      </example>

      <p>The <strong>printenv</strong> element is available only in
      Apache 1.2 and above.</p>
    </dd>
      <dt><strong>set</strong></dt>

      <dd>
        This sets the value of a variable. Attributes: 

        <dl>
          <dt><strong>var</strong></dt>

          <dd>The name of the variable to set.</dd>

          <dt><strong>value</strong></dt>

          <dd>The value to give a variable.</dd>
        </dl>
        <p>For example:</p>
        
        <example>
        &lt;!--#set var="category" value="help" --&gt;
        </example>

      <p>The <strong>set</strong> element is available only in
      Apache 1.2 and above.</p>
      </dd>
    </dl>
</section>

<section id="includevars">
    <title>Include Variables</title>

    <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>DATE_GMT</dt>

      <dd>The current date in Greenwich Mean Time.</dd>

      <dt>DATE_LOCAL</dt>

      <dd>The current date in the local time zone.</dd>

      <dt>DOCUMENT_NAME</dt>

      <dd>The filename (excluding directories) of the document
      requested by the user.</dd>

      <dt>DOCUMENT_URI</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> then URL for the current document.</dd>

      <dt>LAST_MODIFIED</dt>

      <dd>The last modification date of the document requested by
      the user.</dd>
    </dl>
</section>

<section>
    <title>Variable Substitution</title>

    <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>, and <code>set</code> directives, as well
    as the arguments to conditional operators. You can insert a
    literal dollar sign into the string using backslash
    quoting:</p>
<example>
    &lt;!--#if expr="$a = \$test" --&gt;
</example>

    <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>

<example>
    &lt;!--#set var="Zed" value="${REMOTE_HOST}_${REQUEST_METHOD}" --&gt;
</example>

    <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>

    <p>EXAMPLE: the below example will print "in foo" if the
    DOCUMENT_URI is /foo/file.html, "in bar" if it is
    /bar/file.html and "in neither" otherwise:</p>

<example>
    &lt;!--#if expr="\"$DOCUMENT_URI\" = \"/foo/file.html\"" --&gt;<br />
    in foo<br />
    &lt;!--#elif expr="\"$DOCUMENT_URI\" = \"/bar/file.html\"" --&gt;<br />
    in bar<br />
    &lt;!--#else --&gt;<br />
    in neither<br />
    &lt;!--#endif --&gt;
</example>
</section>

<section id="flowctrl">
    <title>Flow Control Elements</title>

    <p>These are available in Apache 1.2 and above. The basic flow
    control elements are:</p>

<example>
    &lt;!--#if expr="<em>test_condition</em>" --&gt;<br />
    &lt;!--#elif expr="<em>test_condition</em>" --&gt;<br />
    &lt;!--#else --&gt;<br />
    &lt;!--#endif --&gt;
</example>

    <p>The <strong><code>if</code></strong> 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 <strong><code>elif</code></strong>,
    <strong><code>else</code></strong>. or
    <strong><code>endif</code></strong> element is included in the
    output stream.</p>

    <p>The <strong><code>elif</code></strong> or
    <strong><code>else</code></strong> statements are be used the
    put text into the output stream if the original test_condition
    was false. These elements are optional.</p>

    <p>The <strong><code>endif</code></strong> element ends the
    <strong><code>if</code></strong> element and is required.</p>

    <p><em>test_condition</em> is one of the following:</p>

    <dl>
      <dt><em>string</em></dt>

      <dd>true if <em>string</em> is not empty</dd>

      <dt><em>string1</em> = <em>string2</em><br />
       <em>string1</em> != <em>string2</em><br />
       <em>string1</em> &lt; <em>string2</em><br />
       <em>string1</em> &lt;= <em>string2</em><br />
       <em>string1</em> &gt; <em>string2</em><br />
       <em>string1</em> &gt;= <em>string2</em></dt>

      <dd>Compare string1 with string 2. If string2 has the form
      <em>/string/</em> then it is compared as a regular
      expression. Regular expressions have the same syntax as those
      found in the Unix <code>egrep</code> command.</dd>

      <dt>( <em>test_condition</em> )</dt>

      <dd>true if <em>test_condition</em> is true</dd>

      <dt>! <em>test_condition</em></dt>

      <dd>true if <em>test_condition</em> is false</dd>

      <dt><em>test_condition1</em> &amp;&amp;
      <em>test_condition2</em></dt>

      <dd>true if both <em>test_condition1</em> and
      <em>test_condition2</em> are true</dd>

      <dt><em>test_condition1</em> || <em>test_condition2</em></dt>

      <dd>true if either <em>test_condition1</em> or
      <em>test_condition2</em> is true</dd>
    </dl>

    <p>"<em>=</em>" and "<em>!=</em>" bind more tightly than
    "<em>&amp;&amp;</em>" and "<em>||</em>". "<em>!</em>" binds
    most tightly. Thus, the following are equivalent:</p>

<example>
    &lt;!--#if expr="$a = test1 &amp;&amp; $b = test2" --&gt;<br />
    &lt;!--#if expr="($a = test1) &amp;&amp; ($b = test2)" --&gt;
</example>

    <p>Anything that's not recognized as a variable or an operator
    is treated as a string. Strings can also be quoted:
    <em>'string'</em>. 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>

<example>
    <pre><em>string1    string2</em>  results in <em>string1 string2</em></pre>
    <pre><em>'string1    string2'</em> results in <em>string1    string2</em></pre>
</example>

</section>

<section>
    <title>Using Server Side Includes for ErrorDocuments</title>

    <p>There is <a href="../misc/custom_errordocs.html">a document</a>
    which describes how to use the features of mod_include to offer
    internationalized customized server error documents.</p>

</section>

<section><title>PATH_INFO with Server Side Includes</title>

    <p>Files processed for server-side includes no longer accept
    requests with PATH_INFO (trailing pathname information) by
    default.  You can use the <directive
    module="core">AcceptPathInfo</directive> directive to
    configure the server to accept requests with PATH_INFO.</p>

</section>

<directivesynopsis>
<name>SSIEndTag</name>
<description>Changes the string that mod_include looks for to end an
include command.</description>
<syntax>SSIEndTag <em>tag</em></syntax>
<default>SSIEndTag &quot;--&gt;&quot;</default>
<contextlist><context>server config</context>
<context>virtual host</context></contextlist>
<override>FileInfo</override>
<compatibility>Available in version 2.0.30 and later.
</compatibility>

<usage>
    <p>This directive changes the string that mod_include looks for 
    to mark the end of a include command.</p>

</usage>
<seealso><directive>SSIStartTag</directive></seealso>
</directivesynopsis>

<directivesynopsis>
<name>SSIUndefinedEcho</name>
<description>Changes the string that mod_include displays when
a variable isn't set.</description>
<syntax>SSIUndefinedEcho <em>tag</em></syntax>
<default>SSIUndefinedEcho &quot;&lt;-- undef --&gt;&quot;</default>
<contextlist><context>server config</context>
<context>virtual host</context></contextlist>
<override>FileInfo</override>
<compatibility>Available in version 2.0.34 and later.
</compatibility>

<usage>
    <p>This directive changes the string that mod_include displays
    when a variable is not set and &quot;echoed&quot;.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>SSIErrorMsg</name>
<description>Changes the error message displayed when there is an error</description>
<syntax>SSIErrorMsg <em>message</em></syntax>
<default>SSIErrorMsg 
&quot;[an error occurred while processing this directive]&quot;</default>
<contextlist>
<context>server config</context>
<context>virtual host</context>
<context>directory</context>
<context>.htaccess</context>
</contextlist>
<override></override>
<compatibility>Available in version 2.0.30 and later.</compatibility>

<usage>
    <p>The SSIErrorMsg directive changes the error message displayed
    when mod_include encounters an error. For production servers you
    may consider changing the default error message to
    <code>&quot;&lt;-- Error --&gt;&quot;</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=<em>message</em> --&gt;</code> element.</p>

</usage>
</directivesynopsis>

<directivesynopsis>
<name>SSIStartTag</name>
<description></description>
<syntax>Changes the string that mod_include looks for to start an
include element</syntax>
<default>SSIStartTag &quot;&lt;--!&quot;</default>
<contextlist>
<context>server config</context>
<context>virtual host</context>
</contextlist>
<override></override>
<compatibility>Available in version 2.0.30 and later.</compatibility>

<usage>

    <p>This directive changes the string that mod_include looks for 
    to mark an include element to process.</p>

    <p>You may want to use this option if have 2 servers parsing the
    output of a file each processing different commands (possibly at
    different times).</p> 

</usage>
<seealso><directive>SSIEndTag</directive></seealso>
</directivesynopsis>

<directivesynopsis>
<name>SSITimeFormat</name>
<description>Configures the format in which date strings are 
displayed</description>
<syntax>SSITimeFormat <em>formatstring</em></syntax>
<default>SSITimeFormat &quot;%A, %d-%b-%Y %H:%M:%S %Z&quot;</default>
<contextlist>
<context>server config</context>
<context>virtual host</context>
<context>directory</context>
<context>.htaccess</context>
</contextlist>
<override></override>
<compatibility>Available in version 2.0.30 and later.</compatibility>

<usage>
<p>This directive changes the format in which date strings are displayed 
    when echoing DATE environment variables.  The <em>formatstring</em>
    is as in strftime(3) from the C standard library.</p>

    <p>This directive has the same effect as the <code>&lt;--#config
    timefmt=<em>formatstring</em> --&gt;</code> element.</p>
</usage>
</directivesynopsis>

<directivesynopsis>
<name>XBitHack</name>
<description>Parse SSI directives in files with the execute 
bit set</description>
<syntax>XBitHack on|off|full</syntax>
<default>XBitHack off</default>
<contextlist>
<context>server config</context>
<context>virtual host</context>
<context>directory</context>
<context>.htaccess</context>
</contextlist>
<override>Options</override>
<compatibility></compatibility>

<usage>
    <p>The XBitHack directives controls the parsing of ordinary
    html documents. This directive only affects files associated
    with the MIME type <code>text/html</code>. XBitHack can take on
    the following values:</p>

    <dl>
      <dt>off</dt>

      <dd>No special treatment of executable files.</dd>

      <dt>on</dt>

      <dd>Any text/html file that has the user-execute bit set will 
      be treated as a server-parsed html document.</dd>

      <dt>full</dt>

      <dd>
        As for <code>on</code> but also test the group-execute bit.
        If it is set, then set the Last-modified 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. 

        <note><strong>Note:</strong> 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).</note>
      </dd>
    </dl>

    </usage>
</directivesynopsis>

</modulesynopsis>