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10 The ASF licenses this file to You under the Apache License, Version 2.0
11 (the "License"); you may not use this file except in compliance with
12 the License. You may obtain a copy of the License at
14 http://www.apache.org/licenses/LICENSE-2.0
16 Unless required by applicable law or agreed to in writing, software
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23 <modulesynopsis metafile="mod_include.xml.meta">
25 <name>mod_include</name>
26 <description>Server-parsed html documents (Server Side Includes)</description>
28 <sourcefile>mod_include.c</sourcefile>
29 <identifier>include_module</identifier>
30 <compatibility>Implemented as an output filter since Apache
34 <p>This module provides a filter which will process files
35 before they are sent to the client. The processing is
36 controlled by specially formatted SGML comments, referred to as
37 <dfn>elements</dfn>. These elements allow conditional text, the
38 inclusion of other files or programs, as well as the setting and
39 printing of environment variables.</p>
41 <seealso><directive module="core">Options</directive></seealso>
42 <seealso><directive module="core">AcceptPathInfo</directive></seealso>
43 <seealso><a href="../filter.html">Filters</a></seealso>
44 <seealso><a href="../howto/ssi.html">SSI Tutorial</a></seealso>
46 <section id="enabling">
47 <title>Enabling Server-Side Includes</title>
49 <p>Server Side Includes are implemented by the
50 <code>INCLUDES</code> <a href="../filter.html">filter</a>. If
51 documents containing server-side include directives are given
52 the extension .shtml, the following directives will make Apache
53 parse them and assign the resulting document the mime type of
54 <code>text/html</code>:</p>
56 <highlight language="config">
57 AddType text/html .shtml
58 AddOutputFilter INCLUDES .shtml
61 <p>The following directive must be given for the directories
62 containing the shtml files (typically in a
63 <directive module="core" type="section">Directory</directive> section,
64 but this directive is also valid in <code>.htaccess</code> files if
65 <directive module="core">AllowOverride</directive> <code>Options</code>
68 <highlight language="config">
72 <p>For backwards compatibility, the <code>server-parsed</code>
73 <a href="../handler.html">handler</a> also activates the
74 INCLUDES filter. As well, Apache will activate the INCLUDES
75 filter for any document with mime type
76 <code>text/x-server-parsed-html</code> or
77 <code>text/x-server-parsed-html3</code> (and the resulting
78 output will have the mime type <code>text/html</code>).</p>
80 <p>For more information, see our <a
81 href="../howto/ssi.html">Tutorial on Server Side Includes</a>.</p>
82 </section> <!-- /enabling -->
84 <section id="pathinfo">
85 <title>PATH_INFO with Server Side Includes</title>
87 <p>Files processed for server-side includes no longer accept
88 requests with <code>PATH_INFO</code> (trailing pathname information)
89 by default. You can use the <directive
90 module="core">AcceptPathInfo</directive> directive to
91 configure the server to accept requests with <code>PATH_INFO</code>.</p>
92 </section> <!-- /pathinfo -->
94 <section id="elements"><title>Basic Elements</title>
95 <p>The document is parsed as an HTML document, with special
96 commands embedded as SGML comments. A command has the syntax: </p>
99 <!--#<var>element</var> <var>attribute</var>=<var>value</var>
100 <var>attribute</var>=<var>value</var> ... -->
103 <p>The value will often be enclosed in double quotes, but single
104 quotes (<code>'</code>) and backticks (<code>`</code>) are also
105 possible. Many commands only allow a single attribute-value pair.
106 Note that the comment terminator (<code>--></code>) should be
107 preceded by whitespace to ensure that it isn't considered part of
108 an SSI token. Note that the leading <code><!--#</code> is <em>one</em>
109 token and may not contain any whitespaces.</p>
111 <p>The allowed elements are listed in the following table:</p>
114 <tr><th>Element</th><th>Description</th></tr>
115 <tr><td><code><a href="#element.config">config</a></code></td>
116 <td>configure output formats</td></tr>
117 <tr><td><code><a href="#element.echo">echo</a></code></td>
118 <td>print variables</td></tr>
119 <tr><td><code><a href="#element.exec">exec</a></code></td>
120 <td>execute external programs</td></tr>
121 <tr><td><code><a href="#element.fsize">fsize</a></code></td>
122 <td>print size of a file</td></tr>
123 <tr><td><code><a href="#element.flastmod">flastmod</a></code></td>
124 <td>print last modification time of a file</td></tr>
125 <tr><td><code><a href="#element.include">include</a></code></td>
126 <td>include a file</td></tr>
127 <tr><td><code><a href="#element.printenv">printenv</a></code></td>
128 <td>print all available variables</td></tr>
129 <tr><td><code><a href="#element.set">set</a></code></td>
130 <td>set a value of a variable</td></tr>
133 <p>SSI elements may be defined by modules other than
134 <module>mod_include</module>. In fact, the <code><a
135 href="#element.exec">exec</a></code> element is provided by
136 <module>mod_cgi</module>, and will only be available if this
137 module is loaded.</p>
139 <section id="element.config"><title>The config Element</title>
140 <p>This command controls various aspects of the parsing. The
141 valid attributes are:</p>
144 <dt><code>echomsg</code> (<em>Apache 2.1 and later</em>)</dt>
145 <dd>The value is a message that is sent back to the
146 client if the <code><a href="#element.echo">echo</a></code> element
147 attempts to echo an undefined variable. This overrides any <directive
148 module="mod_include">SSIUndefinedEcho</directive> directives.</dd>
150 <dt><code>errmsg</code></dt>
151 <dd>The value is a message that is sent back to the
152 client if an error occurs while parsing the
153 document. This overrides any <directive
154 module="mod_include">SSIErrorMsg</directive> directives.</dd>
156 <dt><code>sizefmt</code></dt>
157 <dd>The value sets the format to be used when displaying
158 the size of a file. Valid values are <code>bytes</code>
159 for a count in bytes, or <code>abbrev</code> for a count
160 in Kb or Mb as appropriate, for example a size of 1024 bytes
161 will be printed as "1K".</dd>
163 <dt><code>timefmt</code></dt>
164 <dd>The value is a string to be used by the
165 <code>strftime(3)</code> library routine when printing
168 </section> <!-- /config -->
170 <section id="element.echo"><title>The echo Element</title>
171 <p>This command prints one of the <a href="#includevars">include
172 variables</a> defined below. If the variable is unset, the result is
173 determined by the <directive module="mod_include"
174 >SSIUndefinedEcho</directive> directive. Any dates printed are
175 subject to the currently configured <code>timefmt</code>.</p>
180 <dt><code>var</code></dt>
181 <dd>The value is the name of the variable to print.</dd>
183 <dt><code>decoding</code></dt>
184 <dd><p>Specifies whether Apache should strip an encoding from
185 the variable before processing the variable further. The default
186 is <code>none</code>, where no decoding will be done. If set to
187 <code>url</code>, then URL decoding (also known as %-encoding;
188 this is appropriate for use within URLs in links, etc.) will be
189 performed. If set to <code>urlencoded</code>,
190 application/x-www-form-urlencoded compatible encoding (found in
191 query strings) will be stripped. If set to <code>base64</code>,
192 base64 will be decoded, and if set to <code>entity</code>, HTML
193 entity encoding will be stripped. Decoding is done prior to any
194 further encoding on the variable. Multiple encodings can be
195 stripped by specifying more than one comma separated encoding.
196 The decoding setting will remain in effect until the next decoding
197 attribute is encountered, or the element ends.</p>
199 <p>The <code>decoding</code> attribute must <em>precede</em> the
200 corresponding <code>var</code> attribute to be effective.</p>
203 <dt><code>encoding</code></dt>
204 <dd><p>Specifies how Apache should encode special characters
205 contained in the variable before outputting them. If set
206 to <code>none</code>, no encoding will be done. If set to
207 <code>url</code>, then URL encoding (also known as %-encoding;
208 this is appropriate for use within URLs in links, etc.) will be
209 performed. If set to <code>urlencoded</code>,
210 application/x-www-form-urlencoded compatible encoding will be
211 performed instead, and should be used with query strings. If set
212 to <code>base64</code>, base64 encoding will be performed. At
213 the start of an <code>echo</code> element, the default is set to
214 <code>entity</code>, resulting in entity encoding (which is
215 appropriate in the context of a block-level HTML element,
216 <em>e.g.</em> a paragraph of text). This can be changed by adding
217 an <code>encoding</code> attribute, which will remain in effect
218 until the next <code>encoding</code> attribute is encountered or
219 the element ends, whichever comes first.</p>
221 <p>The <code>encoding</code> attribute must <em>precede</em> the
222 corresponding <code>var</code> attribute to be effective.</p>
224 <note type="warning">
225 In order to avoid cross-site scripting issues, you should
226 <em>always</em> encode user supplied data.
230 </section> <!-- /echo -->
232 <section id="element.exec"><title>The exec Element</title>
233 <p>The <code>exec</code> command executes a given shell command or
234 CGI script. It requires <module>mod_cgi</module> to be present
235 in the server. If <directive module="core">Options</directive>
236 <code>IncludesNOEXEC</code> is set, this command is completely
237 disabled. The valid attributes are:</p>
240 <dt><code>cgi</code></dt>
241 <dd><p>The value specifies a (%-encoded) URL-path to
242 the CGI script. If the path does not begin with a slash (/),
243 then it is taken to be relative to the current
244 document. The document referenced by this path is
245 invoked as a CGI script, even if the server would not
246 normally recognize it as such. However, the directory
247 containing the script must be enabled for CGI scripts
248 (with <directive module="mod_alias">ScriptAlias</directive>
249 or <directive module="core">Options</directive>
250 <code>ExecCGI</code>).</p>
252 <p>The CGI script is given the <code>PATH_INFO</code> and query
253 string (<code>QUERY_STRING</code>) of the original request from the
254 client; these <em>cannot</em> be specified in the URL path. The
255 include variables will be available to the script in addition to
256 the standard <a href="mod_cgi.html">CGI</a> environment.</p>
258 <example><title>Example</title>
259 <!--#exec cgi="/cgi-bin/example.cgi" -->
262 <p>If the script returns a <code>Location:</code> header instead of
263 output, then this will be translated into an HTML anchor.</p>
265 <p>The <code><a href="#includevirtual">include virtual</a></code>
266 element should be used in preference to <code>exec cgi</code>. In
267 particular, if you need to pass additional arguments to a CGI program,
268 using the query string, this cannot be done with <code>exec
269 cgi</code>, but can be done with <code>include virtual</code>, as
273 <!--#include virtual="/cgi-bin/example.cgi?argument=value" -->
277 <dt><code>cmd</code></dt>
278 <dd><p>The server will execute the given string using
279 <code>/bin/sh</code>. The <a href="#includevars"
280 >include variables</a> are available to the command, in addition
281 to the usual set of CGI variables.</p>
283 <p>The use of <code><a href="#includevirtual"
284 >#include virtual</a></code> is almost always prefered to using
285 either <code>#exec cgi</code> or <code>#exec cmd</code>. The former
286 (<code>#include virtual</code>) uses the standard Apache sub-request
287 mechanism to include files or scripts. It is much better tested and
290 <p>In addition, on some platforms, like Win32, and on unix when
291 using <a href="../suexec.html">suexec</a>, you cannot pass arguments
292 to a command in an <code>exec</code> directive, or otherwise include
293 spaces in the command. Thus, while the following will work under a
294 non-suexec configuration on unix, it will not produce the desired
295 result under Win32, or when running suexec:</p>
298 <!--#exec cmd="perl /path/to/perlscript arg1 arg2" -->
302 </section> <!-- /exec -->
304 <section id="element.fsize"><title>The fsize Element</title>
305 <p>This command prints the size of the specified file, subject
306 to the <code>sizefmt</code> format specification. Attributes:</p>
309 <dt><code>file</code></dt>
310 <dd>The value is a path relative to the directory
311 containing the current document being parsed.</dd>
313 <dt><code>virtual</code></dt>
314 <dd>The value is a (%-encoded) URL-path. If it does not begin with
315 a slash (/) then it is taken to be relative to the current document.
316 Note, that this does <em>not</em> print the size of any CGI output,
317 but the size of the CGI script itself.</dd>
319 </section> <!-- /fsize -->
321 <section id="element.flastmod"><title>The flastmod Element</title>
322 <p>This command prints the last modification date of the
323 specified file, subject to the <code>timefmt</code> format
324 specification. The attributes are the same as for the
325 <code><a href="#element.fsize">fsize</a></code> command.</p>
326 </section> <!-- /flastmod -->
328 <section id="element.include"><title>The include Element</title>
329 <p>This command inserts the text of another document or file
330 into the parsed file. Any included file is subject to the usual
331 access control. If the directory containing the parsed file has
332 <a href="core.html#options">Options</a>
333 <code>IncludesNOEXEC</code> set, then only documents with a text
334 <glossary>MIME-type</glossary> (<code>text/plain</code>,
335 <code>text/html</code> etc.) will be included. Otherwise CGI
336 scripts are invoked as normal using the complete URL given in
337 the command, including any query string.</p>
339 <p>An attribute defines the location of the document, and may
340 appear more than once in an include element; an inclusion is
341 done for each attribute given to the include command in turn.
342 The valid attributes are:</p>
345 <dt><code>file</code></dt>
346 <dd>The value is a path relative to the directory
347 containing the current document being parsed. It cannot
348 contain <code>../</code>, nor can it be an absolute path.
349 Therefore, you cannot include files that are outside of the
350 document root, or above the current document in the directory
351 structure. The <code>virtual</code> attribute should always be
352 used in preference to this one.</dd>
354 <dt><code><a id="includevirtual" name="includevirtual"
355 >virtual</a></code></dt>
356 <dd><p>The value is a (%-encoded) URL-path. The URL cannot contain a
357 scheme or hostname, only a path and an optional query string. If it
358 does not begin with a slash (/) then it is taken to be relative to the
359 current document.</p>
361 <p>A URL is constructed from the attribute, and the output the
362 server would return if the URL were accessed by the client is
363 included in the parsed output. Thus included files can be nested.</p>
365 <p>If the specified URL is a CGI program, the program will be
366 executed and its output inserted in place of the directive in the
367 parsed file. You may include a query string in a CGI url:</p>
370 <!--#include virtual="/cgi-bin/example.cgi?argument=value" -->
373 <p><code>include virtual</code> should be used in preference
374 to <code>exec cgi</code> to include the output of CGI programs
375 into an HTML document.</p>
377 <p>If the <directive module="mod_request">KeptBodySize</directive>
378 directive is correctly configured and valid for this included
379 file, attempts to POST requests to the enclosing HTML document
380 will be passed through to subrequests as POST requests as well.
381 Without the directive, all subrequests are processed as GET
386 <dt><code>onerror</code></dt>
387 <dd><p>The value is a (%-encoded) URL-path which is shown should a
388 previous attempt to include a file or virtual attribute failed.
389 To be effective, this attribute must be specified after the
390 file or virtual attributes being covered. If the attempt to
391 include the onerror path fails, or if onerror is not specified, the
392 default error message will be included.</p>
395 # Simple example<br />
396 <!--#include virtual="/not-exist.html" onerror="/error.html" -->
400 # Dedicated onerror paths<br />
401 <!--#include virtual="/path-a.html" onerror="/error-a.html" virtual="/path-b.html" onerror="/error-b.html" -->
406 </section> <!-- /include -->
408 <section id="element.printenv"><title>The printenv Element</title>
409 <p>This prints out a listing of all existing variables and
410 their values. Special characters are entity encoded (see the <code><a
411 href="#element.echo">echo</a></code> element for details)
412 before being output. There are no attributes.</p>
414 <example><title>Example</title>
415 <!--#printenv -->
417 </section> <!-- /printenv -->
419 <section id="element.set"><title>The set Element</title>
420 <p>This sets the value of a variable. Attributes:</p>
423 <dt><code>var</code></dt>
424 <dd>The name of the variable to set.</dd>
426 <dt><code>value</code></dt>
427 <dd>The value to give a variable.</dd>
429 <dt><code>decoding</code></dt>
430 <dd><p>Specifies whether Apache should strip an encoding from
431 the variable before processing the variable further. The default
432 is <code>none</code>, where no decoding will be done. If set to
433 <code>url</code>, <code>urlencoded</code>, <code>base64</code>
434 or <code>entity</code>, URL decoding,
435 application/x-www-form-urlencoded decoding, base64 decoding or HTML
436 entity decoding will be performed respectively. More than one
437 decoding can be specified by separating with commas. The decoding
438 setting will remain in effect until the next decoding attribute
439 is encountered, or the element ends. The <code>decoding</code>
440 attribute must <em>precede</em> the corresponding
441 <code>var</code> attribute to be effective.</p>
444 <dt><code>encoding</code></dt>
445 <dd><p>Specifies how Apache should encode special characters
446 contained in the variable before setting them. The default is
447 <code>none</code>, where no encoding will be done. If set to
448 <code>url</code>, <code>urlencoding</code>, <code>base64</code>
449 or <code>entity</code>, URL encoding,
450 application/x-www-form-urlencoded encoding, base64 encoding or
451 HTML entity encoding will be performed respectively. More than
452 one encoding can be specified by separating with commas. The
453 encoding setting will remain in effect until the next encoding
454 attribute is encountered, or the element ends. The
455 <code>encoding</code> attribute must <em>precede</em> the
456 corresponding <code>var</code> attribute to be effective.
457 Encodings are applied after all decodings have been
462 <example><title>Example</title>
463 <!--#set var="category" value="help" -->
465 </section> <!-- /set -->
466 </section> <!-- /basic elements -->
468 <section id="includevars">
469 <title>Include Variables</title>
471 <p>In addition to the variables in the standard CGI environment,
472 these are available for the <code>echo</code> command, for
473 <code>if</code> and <code>elif</code>, and to any program
474 invoked by the document.</p>
477 <dt><code>DATE_GMT</code></dt>
478 <dd>The current date in Greenwich Mean Time.</dd>
480 <dt><code>DATE_LOCAL</code></dt>
481 <dd>The current date in the local time zone.</dd>
483 <dt><code>DOCUMENT_NAME</code></dt>
484 <dd>The filename (excluding directories) of the document
485 requested by the user.</dd>
487 <dt><code>DOCUMENT_URI</code></dt>
488 <dd>The (%-decoded) URL path of the document requested by the
489 user. Note that in the case of nested include files, this is
490 <em>not</em> the URL for the current document. Note also that
491 if the URL is modified internally (e.g. by an <directive
492 module="mod_alias">alias</directive> or <directive
493 module="mod_dir">directoryindex</directive>), the modified
496 <dt><code>LAST_MODIFIED</code></dt>
497 <dd>The last modification date of the document requested by
500 <dt><code>QUERY_STRING_UNESCAPED</code></dt>
501 <dd>If a query string is present, this variable contains the
502 (%-decoded) query string, which is <em>escaped</em> for shell
503 usage (special characters like <code>&</code> etc. are
504 preceded by backslashes).</dd>
508 <section id="substitution"><title>Variable Substitution</title>
510 <p>Variable substitution is done within quoted strings in most
511 cases where they may reasonably occur as an argument to an SSI
512 directive. This includes the <code>config</code>,
513 <code>exec</code>, <code>flastmod</code>, <code>fsize</code>,
514 <code>include</code>, <code>echo</code>, and <code>set</code>
515 directives. If <directive module="mod_include"
516 >SSILegacyExprParser</directive> is set to <code>on</code>,
517 substitution also occures in the arguments to conditional operators.
518 You can insert a literal dollar sign into the string using backslash
522 <!--#set var="cur" value="\$test" -->
525 <p>If a variable reference needs to be substituted in the
526 middle of a character sequence that might otherwise be
527 considered a valid identifier in its own right, it can be
528 disambiguated by enclosing the reference in braces,
529 <em>a la</em> shell substitution:</p>
532 <!--#set var="Zed" value="${REMOTE_HOST}_${REQUEST_METHOD}" -->
535 <p>This will result in the <code>Zed</code> variable being set
536 to "<code>X_Y</code>" if <code>REMOTE_HOST</code> is
537 "<code>X</code>" and <code>REQUEST_METHOD</code> is
538 "<code>Y</code>".</p>
541 <section id="flowctrl">
542 <title>Flow Control Elements</title>
544 <p>The basic flow control elements are:</p>
547 <!--#if expr="<var>test_condition</var>" --><br />
548 <!--#elif expr="<var>test_condition</var>" --><br />
549 <!--#else --><br />
553 <p>The <code>if</code> element works like an if statement in a
554 programming language. The test condition is evaluated and if
555 the result is true, then the text until the next <code>elif</code>,
556 <code>else</code> or <code>endif</code> element is included in the
559 <p>The <code>elif</code> or <code>else</code> statements are used
560 to put text into the output stream if the original
561 <var>test_condition</var> was false. These elements are optional.</p>
563 <p>The <code>endif</code> element ends the <code>if</code> element
566 <p><var>test_condition</var> is a boolean expression tha follows the
567 <a href="../expr.html">ap_expr</a> syntax. The syntax can be changed
568 to be compatible with Apache HTTPD 2.2.x using <directive
569 module="mod_include">SSILegacyExprParser</directive>.</p>
571 <p>The SSI variables set with the <code>var</code> element are exported
572 into the request environment and can be accessed with the
573 <code>reqenv</code> function. As a short-cut, the function name
574 <code>v</code> is also available inside <module>mod_include</module>.</p>
576 <p>The below example will print "from local net" if client IP address
577 belongs to the 10.0.0.0/8 subnet.</p>
580 <!--#if expr='-R "10.0.0.0/8"' --><br />
584 <!--#else --><br />
586 from somewhere else<br />
591 <p>The below example will print "foo is bar" if the variable
592 <code>foo</code> is set to the value "bar".</p>
595 <!--#if expr='v("foo") = "bar"' --><br />
602 <note><title>Reference Documentation</title>
603 <p>See also: <a href="../expr.html">Expressions in Apache HTTP Server</a>,
604 for a complete reference and examples. The <em>restricted</em> functions
605 are not available inside <module>mod_include</module></p>
609 <section id="legacyexpr">
610 <title>Legacy expression syntax</title>
612 <p>This section describes the syntax of the <code>#if expr</code>
613 element if <directive module="mod_include">SSILegacyExprParser</directive>
614 is set to <code>on</code>.</p>
617 <dt><code><var>string</var></code></dt>
618 <dd>true if <var>string</var> is not empty</dd>
620 <dt><code><var>-A string</var></code></dt>
621 <dd><p>true if the URL represented by the string is accessible by
622 configuration, false otherwise. This is useful where content on a
623 page is to be hidden from users who are not authorized to view the
624 URL, such as a link to that URL. Note that the URL is only tested
625 for whether access would be granted, not whether the URL exists.</p>
627 <example><title>Example</title>
628 <!--#if expr="-A /private" --><br />
630 Click <a href="/private">here</a> to access private
637 <dt><code><var>string1</var> = <var>string2</var><br />
638 <var>string1</var> == <var>string2</var><br />
639 <var>string1</var> != <var>string2</var></code></dt>
641 <dd><p>Compare <var>string1</var> with <var>string2</var>. If
642 <var>string2</var> has the form <code>/<var>string2</var>/</code>
643 then it is treated as a regular expression. Regular expressions are
644 implemented by the <a href="http://www.pcre.org">PCRE</a> engine and
645 have the same syntax as those in <a href="http://www.perl.com">perl
646 5</a>. Note that <code>==</code> is just an alias for <code>=</code>
647 and behaves exactly the same way.</p>
649 <p>If you are matching positive (<code>=</code> or <code>==</code>), you
650 can capture grouped parts of the regular expression. The captured parts
651 are stored in the special variables <code>$1</code> ..
652 <code>$9</code>. The whole string matched by the regular expression is
653 stored in the special variable <code>$0</code></p>
655 <example><title>Example</title>
656 <!--#if expr="$QUERY_STRING = /^sid=([a-zA-Z0-9]+)/" --><br />
658 <!--#set var="session" value="$1" --><br />
664 <dt><code><var>string1</var> < <var>string2</var><br />
665 <var>string1</var> <= <var>string2</var><br />
666 <var>string1</var> > <var>string2</var><br />
667 <var>string1</var> >= <var>string2</var></code></dt>
669 <dd>Compare <var>string1</var> with <var>string2</var>. Note, that
670 strings are compared <em>literally</em> (using
671 <code>strcmp(3)</code>). Therefore the string "100" is less than
674 <dt><code>( <var>test_condition</var> )</code></dt>
675 <dd>true if <var>test_condition</var> is true</dd>
677 <dt><code>! <var>test_condition</var></code></dt>
678 <dd>true if <var>test_condition</var> is false</dd>
680 <dt><code><var>test_condition1</var> &&
681 <var>test_condition2</var></code></dt>
682 <dd>true if both <var>test_condition1</var> and
683 <var>test_condition2</var> are true</dd>
685 <dt><code><var>test_condition1</var> ||
686 <var>test_condition2</var></code></dt>
687 <dd>true if either <var>test_condition1</var> or
688 <var>test_condition2</var> is true</dd>
691 <p>"<code>=</code>" and "<code>!=</code>" bind more tightly than
692 "<code>&&</code>" and "<code>||</code>". "<code>!</code>" binds
693 most tightly. Thus, the following are equivalent:</p>
696 <!--#if expr="$a = test1 && $b = test2" --><br />
697 <!--#if expr="($a = test1) && ($b = test2)" -->
700 <p>The boolean operators <code>&&</code> and <code>||</code>
701 share the same priority. So if you want to bind such an operator more
702 tightly, you should use parentheses.</p>
704 <p>Anything that's not recognized as a variable or an operator
705 is treated as a string. Strings can also be quoted:
706 <code>'string'</code>. Unquoted strings can't contain whitespace
707 (blanks and tabs) because it is used to separate tokens such as
708 variables. If multiple strings are found in a row, they are
709 concatenated using blanks. So,</p>
712 <p><code><var>string1</var> <var
713 >string2</var></code> results in <code><var>string1</var> <var
714 >string2</var></code><br />
718 <code>'<var>string1</var> <var
719 >string2</var>'</code> results in <code><var
720 >string1</var> <var>string2</var></code>.</p>
723 <note><title>Optimization of Boolean Expressions</title>
724 <p>If the expressions become more complex and slow down processing
725 significantly, you can try to optimize them according to the
726 evaluation rules:</p>
728 <li>Expressions are evaluated from left to right</li>
729 <li>Binary boolean operators (<code>&&</code> and <code>||</code>)
730 are short circuited wherever possible. In conclusion with the rule
731 above that means, <module>mod_include</module> evaluates at first
732 the left expression. If the left result is sufficient to determine
733 the end result, processing stops here. Otherwise it evaluates the
734 right side and computes the end result from both left and right
736 <li>Short circuit evaluation is turned off as long as there are regular
737 expressions to deal with. These must be evaluated to fill in the
738 backreference variables (<code>$1</code> .. <code>$9</code>).</li>
740 <p>If you want to look how a particular expression is handled, you can
741 recompile <module>mod_include</module> using the
742 <code>-DDEBUG_INCLUDE</code> compiler option. This inserts for every
743 parsed expression tokenizer information, the parse tree and how it is
744 evaluated into the output sent to the client.</p>
747 <note><title>Escaping slashes in regex strings</title>
748 <p>All slashes which are not intended to act as delimiters in your regex must
749 be escaped. This is regardless of their meaning to the regex engine.</p>
755 <name>SSIEndTag</name>
756 <description>String that ends an include element</description>
757 <syntax>SSIEndTag <var>tag</var></syntax>
758 <default>SSIEndTag "-->"</default>
759 <contextlist><context>server config</context><context>virtual host</context>
761 <compatibility>Available in version 2.0.30 and later.</compatibility>
764 <p>This directive changes the string that <module>mod_include</module>
765 looks for to mark the end of an include element.</p>
767 <highlight language="config">
772 <seealso><directive module="mod_include">SSIStartTag</directive></seealso>
776 <name>SSIUndefinedEcho</name>
777 <description>String displayed when an unset variable is echoed</description>
778 <syntax>SSIUndefinedEcho <var>string</var></syntax>
779 <default>SSIUndefinedEcho "(none)"</default>
780 <contextlist><context>server config</context><context>virtual host</context>
781 <context>directory</context><context>.htaccess</context></contextlist>
782 <override>All</override>
783 <compatibility>Available in version 2.0.34 and later.</compatibility>
786 <p>This directive changes the string that <module>mod_include</module>
787 displays when a variable is not set and "echoed".</p>
789 <highlight language="config">
790 SSIUndefinedEcho "<!-- undef -->"
796 <name>SSIErrorMsg</name>
797 <description>Error message displayed when there is an SSI
799 <syntax>SSIErrorMsg <var>message</var></syntax>
800 <default>SSIErrorMsg "[an error occurred while processing this
801 directive]"</default>
802 <contextlist><context>server config</context><context>virtual host</context>
803 <context>directory</context><context>.htaccess</context></contextlist>
804 <override>All</override>
805 <compatibility>Available in version 2.0.30 and later.</compatibility>
808 <p>The <directive>SSIErrorMsg</directive> directive changes the error
809 message displayed when <module>mod_include</module> encounters an
810 error. For production servers you may consider changing the default
811 error message to <code>"<!-- Error -->"</code> so that
812 the message is not presented to the user.</p>
814 <p>This directive has the same effect as the <code><!--#config
815 errmsg=<var>message</var> --></code> element.</p>
817 <highlight language="config">
818 SSIErrorMsg "<!-- Error -->"
824 <name>SSIStartTag</name>
825 <description>String that starts an include element</description>
826 <syntax>SSIStartTag <var>tag</var></syntax>
827 <default>SSIStartTag "<!--#"</default>
828 <contextlist><context>server config</context><context>virtual host</context>
830 <compatibility>Available in version 2.0.30 and later.</compatibility>
833 <p>This directive changes the string that <module>mod_include</module>
834 looks for to mark an include element to process.</p>
836 <p>You may want to use this option if you have 2 servers parsing the
837 output of a file each processing different commands (possibly at
838 different times).</p>
840 <highlight language="config">
841 SSIStartTag "<%"<br />
845 <p>The example given above, which also specifies a matching
846 <directive module="mod_include">SSIEndTag</directive>, will
847 allow you to use SSI directives as shown in the example
850 <example><title>SSI directives with alternate start and end tags</title>
854 <seealso><directive module="mod_include">SSIEndTag</directive></seealso>
858 <name>SSITimeFormat</name>
859 <description>Configures the format in which date strings are
860 displayed</description>
861 <syntax>SSITimeFormat <var>formatstring</var></syntax>
862 <default>SSITimeFormat "%A, %d-%b-%Y %H:%M:%S %Z"</default>
864 <context>server config</context><context>virtual host</context>
865 <context>directory</context><context>.htaccess</context></contextlist>
866 <override>All</override>
867 <compatibility>Available in version 2.0.30 and later.</compatibility>
870 <p>This directive changes the format in which date strings are displayed
871 when echoing <code>DATE</code> environment variables. The
872 <var>formatstring</var> is as in <code>strftime(3)</code> from the
873 C standard library.</p>
875 <p>This directive has the same effect as the <code><!--#config
876 timefmt=<var>formatstring</var> --></code> element.</p>
878 <highlight language="config">
879 SSITimeFormat "%R, %B %d, %Y"
882 <p>The above directive would cause times to be displayed in the
883 format "22:26, June 14, 2002".</p>
889 <description>Controls whether ETags are generated by the server.</description>
890 <syntax>SSIETag on|off</syntax>
891 <default>SSIETag off</default>
892 <contextlist><context>directory</context><context>.htaccess</context></contextlist>
893 <compatibility>Available in version 2.2.15 and later.</compatibility>
896 <p>Under normal circumstances, a file filtered by <module>mod_include</module>
897 may contain elements that are either dynamically generated, or that may
898 have changed independently of the original file. As a result, by default
899 the server is asked not to generate an <code>ETag</code> header for the
900 response by adding <code>no-etag</code> to the request notes.</p>
902 <p>The <directive>SSIETag</directive> directive suppresses this
903 behaviour, and allows the server to generate an <code>ETag</code> header.
904 This can be used to enable caching of the output. Note that a backend server
905 or dynamic content generator may generate an ETag of its own, ignoring
906 <code>no-etag</code>, and this ETag will be passed by
907 <module>mod_include</module> regardless of the value of this setting.
908 <directive>SSIETag</directive> can take on the following values:</p>
912 <dt><code>off</code></dt>
913 <dd><code>no-etag</code> will be added to the request notes, and the server
914 is asked not to generate an ETag. Where a server ignores the value of
915 <code>no-etag</code> and generates an ETag anyway, the ETag will be
918 <dt><code>on</code></dt>
919 <dd>Existing ETags will be respected, and ETags generated by the server will
920 be passed on in the response.</dd>
928 <name>SSILastModified</name>
929 <description>Controls whether <code>Last-Modified</code> headers are generated by the
930 server.</description>
931 <syntax>SSILastModified on|off</syntax>
932 <default>SSILastModified off</default>
933 <contextlist><context>directory</context><context>.htaccess</context></contextlist>
934 <compatibility>Available in version 2.2.15 and later.</compatibility>
937 <p>Under normal circumstances, a file filtered by <module>mod_include</module>
938 may contain elements that are either dynamically generated, or that may
939 have changed independently of the original file. As a result, by default
940 the <code>Last-Modified</code> header is stripped from the response.</p>
942 <p>The <directive>SSILastModified</directive> directive overrides this
943 behaviour, and allows the <code>Last-Modified</code> header to be respected
944 if already present, or set if the header is not already present. This can
945 be used to enable caching of the output. <directive>SSILastModified</directive>
946 can take on the following values:</p>
950 <dt><code>off</code></dt>
951 <dd>The <code>Last-Modified</code> header will be stripped from responses,
952 unless the <directive module="mod_include">XBitHack</directive> directive
953 is set to <code>full</code> as described below.</dd>
955 <dt><code>on</code></dt>
956 <dd>The <code>Last-Modified</code> header will be respected if already
957 present in a response, and added to the response if the response is a
958 file and the header is missing. The
959 <directive module="mod_include">SSILastModified</directive> directive
960 takes precedence over <directive module="mod_include">XBitHack</directive>.</dd>
968 <name>SSILegacyExprParser</name>
969 <description>Enable compatibility mode for conditional expressions.</description>
970 <syntax>SSILegacyExprParser on|off</syntax>
971 <default>SSILegacyExprParser off</default>
972 <contextlist><context>directory</context><context>.htaccess</context></contextlist>
973 <compatibility>Available in version 2.3.13 and later.</compatibility>
976 <p>As of version 2.3.13, <module>mod_include</module> has switched to the
977 new <a href="../expr.html">ap_expr</a> syntax for conditional expressions
978 in <code>#if</code> flow control elements. This directive allows to
979 switch to the <a href="#legacyexpr">old syntax</a> which is compatible
980 with Apache HTTPD version 2.2.x and earlier.
986 <name>XBitHack</name>
987 <description>Parse SSI directives in files with the execute bit
989 <syntax>XBitHack on|off|full</syntax>
990 <default>XBitHack off</default>
991 <contextlist><context>server config</context><context>virtual host</context>
992 <context>directory</context><context>.htaccess</context></contextlist>
993 <override>Options</override>
996 <p>The <directive>XBitHack</directive> directive controls the parsing
997 of ordinary html documents. This directive only affects files associated
998 with the <glossary>MIME-type</glossary> <code>text/html</code>. <directive
999 >XBitHack</directive> can take on the following values:</p>
1002 <dt><code>off</code></dt>
1003 <dd>No special treatment of executable files.</dd>
1005 <dt><code>on</code></dt>
1006 <dd>Any <code>text/html</code> file that has the user-execute bit
1007 set will be treated as a server-parsed html document.</dd>
1009 <dt><code>full</code></dt>
1010 <dd>As for <code>on</code> but also test the group-execute bit.
1011 If it is set, then set the <code>Last-modified</code> date of the
1012 returned file to be the last modified time of the file. If
1013 it is not set, then no last-modified date is sent. Setting
1014 this bit allows clients and proxies to cache the result of
1017 <note><title>Note</title>
1018 <p>You would not want to use the full option, unless you assure the
1019 group-execute bit is unset for every SSI script which might <code
1020 >#include</code> a CGI or otherwise produces different output on
1021 each hit (or could potentially change on subsequent requests).</p>
1023 <p>The <directive module="mod_include">SSILastModified</directive>
1024 directive takes precedence over the
1025 <directive module="mod_include">XBitHack</directive> directive when
1026 <directive module="mod_include">SSILastModified</directive> is set to
1027 <code>on</code>.</p>
1034 </directivesynopsis>