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10 <title>Expressions in Apache HTTP Server - Apache HTTP Server Version 2.5</title>
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20 <p class="apache">Apache HTTP Server Version 2.5</p>
21 <img alt="" src="./images/feather.png" /></div>
22 <div class="up"><a href="./"><img title="<-" alt="<-" src="./images/left.gif" /></a></div>
24 <a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="./">Version 2.5</a></div><div id="page-content"><div id="preamble"><h1>Expressions in Apache HTTP Server</h1>
26 <p><span>Available Languages: </span><a href="./en/expr.html" title="English"> en </a> |
27 <a href="./fr/expr.html" hreflang="fr" rel="alternate" title="Français"> fr </a></p>
30 <p>Historically, there are several syntax variants for expressions
31 used to express a condition in the different modules of the Apache
32 HTTP Server. There is some ongoing effort to only use a single
33 variant, called <em>ap_expr</em>, for all configuration directives.
34 This document describes the <em>ap_expr</em> expression parser.
36 <p>The <em>ap_expr</em> expression is intended to replace most other
37 expression variants in HTTPD. For example, the deprecated <code class="directive"><a href="./mod/mod_ssl.html#sslrequire">SSLRequire</a></code> expressions can be replaced
38 by <a href="mod/mod_authz_core.html#reqexpr">Require expr</a>. </p>
40 <div id="quickview"><ul id="toc"><li><img alt="" src="./images/down.gif" /> <a href="#grammar">Grammar in Backus-Naur Form notation</a></li>
41 <li><img alt="" src="./images/down.gif" /> <a href="#vars">Variables</a></li>
42 <li><img alt="" src="./images/down.gif" /> <a href="#binop">Binary operators</a></li>
43 <li><img alt="" src="./images/down.gif" /> <a href="#unnop">Unary operators</a></li>
44 <li><img alt="" src="./images/down.gif" /> <a href="#functions">Functions</a></li>
45 <li><img alt="" src="./images/down.gif" /> <a href="#examples">Example expressions</a></li>
46 <li><img alt="" src="./images/down.gif" /> <a href="#other">Other</a></li>
47 <li><img alt="" src="./images/down.gif" /> <a href="#sslrequire">Comparison with SSLRequire</a></li>
48 <li><img alt="" src="./images/down.gif" /> <a href="#compatibility">Version History</a></li>
49 </ul><h3>See also</h3><ul class="seealso"><li><code class="directive"><a href="./mod/core.html#if"><If></a></code></li><li><code class="directive"><a href="./mod/core.html#elseif"><ElseIf></a></code></li><li><code class="directive"><a href="./mod/core.html#else"><Else></a></code></li><li><code class="directive"><a href="./mod/core.html#errordocument">ErrorDocument</a></code></li><li><code class="directive"><a href="./mod/mod_alias.html#alias">Alias</a></code></li><li><code class="directive"><a href="./mod/mod_alias.html#scriptalias">ScriptAlias</a></code></li><li><code class="directive"><a href="./mod/mod_alias.html#redirect">Redirect</a></code></li><li><code class="directive"><a href="./mod/mod_auth_basic.html#authbasicfake">AuthBasicFake</a></code></li><li><code class="directive"><a href="./mod/mod_auth_form.html#authformloginrequiredlocation">AuthFormLoginRequiredLocation</a></code></li><li><code class="directive"><a href="./mod/mod_auth_form.html#authformloginsuccesslocation">AuthFormLoginSuccessLocation</a></code></li><li><code class="directive"><a href="./mod/mod_auth_form.html#authformlogoutlocation">AuthFormLogoutLocation</a></code></li><li><code class="directive"><a href="./mod/mod_authn_core.html#authname">AuthName</a></code></li><li><code class="directive"><a href="./mod/mod_authn_core.html#authtype">AuthType</a></code></li><li><code class="directive"><a href="./mod/mod_rewrite.html#rewritecond">RewriteCond</a></code></li><li><code class="directive"><a href="./mod/mod_setenvif.html#setenvifexpr">SetEnvIfExpr</a></code></li><li><code class="directive"><a href="./mod/mod_headers.html#header">Header</a></code></li><li><code class="directive"><a href="./mod/mod_headers.html#requestheader">RequestHeader</a></code></li><li><code class="directive"><a href="./mod/mod_filter.html#filterprovider">FilterProvider</a></code></li><li><code class="directive"><a href="./mod/mod_crypto.html#cryptokey">CryptoKey</a></code></li><li><code class="directive"><a href="./mod/mod_crypto.html#cryptoiv">CryptoIV</a></code></li><li><a href="mod/mod_authz_core.html#reqexpr">Require expr</a></li><li><a href="mod/mod_authnz_ldap.html#requser">Require ldap-user</a></li><li><a href="mod/mod_authnz_ldap.html#reqgroup">Require ldap-group</a></li><li><a href="mod/mod_authnz_ldap.html#reqdn">Require ldap-dn</a></li><li><a href="mod/mod_authnz_ldap.html#reqattribute">Require ldap-attribute</a></li><li><a href="mod/mod_authnz_ldap.html#reqfilter">Require ldap-filter</a></li><li><a href="mod/mod_authnz_ldap.html#reqsearch">Require ldap-search</a></li><li><a href="mod/mod_authz_dbd.html#reqgroup">Require dbd-group</a></li><li><a href="mod/mod_authz_dbm.html#reqgroup">Require dbm-group</a></li><li><a href="mod/mod_authz_groupfile.html#reqgroup">Require group</a></li><li><a href="mod/mod_authz_host.html#reqhost">Require host</a></li><li><code class="directive"><a href="./mod/mod_ssl.html#sslrequire">SSLRequire</a></code></li><li><code class="directive"><a href="./mod/mod_log_debug.html#logmessage">LogMessage</a></code></li><li><code class="module"><a href="./mod/mod_include.html">mod_include</a></code></li><li><a href="#comments_section">Comments</a></li></ul></div>
50 <div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
52 <h2><a name="grammar" id="grammar">Grammar in Backus-Naur Form notation</a></h2>
54 <p><a href="http://en.wikipedia.org/wiki/Backus%E2%80%93Naur_Form">Backus-Naur
55 Form</a> (BNF) is a notation technique for context-free grammars,
56 often used to describe the syntax of languages used in computing.
57 In most cases, expressions are used to express boolean values.
58 For these, the starting point in the BNF is <code>expr</code>.
59 However, a few directives like <code class="directive"><a href="./mod/mod_log_debug.html#logmessage">LogMessage</a></code> accept expressions
60 that evaluate to a string value. For those, the starting point in
61 the BNF is <code>string</code>.
64 <pre>expr ::= "<strong>true</strong>" | "<strong>false</strong>"
65 | "<strong>!</strong>" expr
66 | expr "<strong>&&</strong>" expr
67 | expr "<strong>||</strong>" expr
68 | "<strong>(</strong>" expr "<strong>)</strong>"
75 | word "<strong>in</strong>" "<strong>{</strong>" wordlist "<strong>}</strong>"
76 | word "<strong>in</strong>" listfunction
77 | word "<strong>=~</strong>" regex
78 | word "<strong>!~</strong>" regex
81 stringcomp ::= word "<strong>==</strong>" word
82 | word "<strong>!=</strong>" word
83 | word "<strong><</strong>" word
84 | word "<strong><=</strong>" word
85 | word "<strong>></strong>" word
86 | word "<strong>>=</strong>" word
88 integercomp ::= word "<strong>-eq</strong>" word | word "<strong>eq</strong>" word
89 | word "<strong>-ne</strong>" word | word "<strong>ne</strong>" word
90 | word "<strong>-lt</strong>" word | word "<strong>lt</strong>" word
91 | word "<strong>-le</strong>" word | word "<strong>le</strong>" word
92 | word "<strong>-gt</strong>" word | word "<strong>gt</strong>" word
93 | word "<strong>-ge</strong>" word | word "<strong>ge</strong>" word
96 | wordlist "<strong>,</strong>" word
98 word ::= word "<strong>.</strong>" word
100 | "<strong>'</strong>" string "<strong>'</strong>"
101 | "<strong>"</strong>" string "<strong>"</strong>"
106 string ::= stringpart
109 stringpart ::= cstring
116 variable ::= "<strong>%{</strong>" varname "<strong>}</strong>"
117 | "<strong>%{</strong>" funcname "<strong>:</strong>" funcargs "<strong>}</strong>"
119 rebackref ::= "<strong>$</strong>" [0-9]
121 function ::= funcname "<strong>(</strong>" wordlist "<strong>)</strong>"
123 listfunction ::= listfuncname "<strong>(</strong>" word "<strong>)</strong>"</pre>
126 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
127 <div class="section">
128 <h2><a name="vars" id="vars">Variables</a></h2>
131 <p>The expression parser provides a number of variables of the form
132 <code>%{HTTP_HOST}</code>. Note that the value of a variable may depend
133 on the phase of the request processing in which it is evaluated. For
134 example, an expression used in an <code class="directive"><If ></code>
135 directive is evaluated before authentication is done. Therefore,
136 <code>%{REMOTE_USER}</code> will not be set in this case.</p>
138 <p>The following variables provide the values of the named HTTP request
139 headers. The values of other headers can be obtained with the
140 <code>req</code> <a href="#functions">function</a>. Using these
141 variables may cause the header name to be added to the Vary
142 header of the HTTP response, except where otherwise noted for the
143 directive accepting the expression. The <code>req_novary</code>
144 <a href="#functions">function</a> may be used to circumvent this
147 <table class="bordered"><tr class="header"><th>Name</th></tr>
148 <tr><td><code>HTTP_ACCEPT</code></td></tr>
149 <tr class="odd"><td><code>HTTP_COOKIE</code></td></tr>
150 <tr><td><code>HTTP_FORWARDED</code></td></tr>
151 <tr class="odd"><td><code>HTTP_HOST</code></td></tr>
152 <tr><td><code>HTTP_PROXY_CONNECTION</code></td></tr>
153 <tr class="odd"><td><code>HTTP_REFERER</code></td></tr>
154 <tr><td><code>HTTP_USER_AGENT</code></td></tr>
157 <p>Other request related variables</p>
159 <table class="bordered"><tr class="header"><th>Name</th><th>Description</th></tr>
160 <tr><td><code>REQUEST_METHOD</code></td>
161 <td>The HTTP method of the incoming request (e.g.
162 <code>GET</code>)</td></tr>
163 <tr class="odd"><td><code>REQUEST_SCHEME</code></td>
164 <td>The scheme part of the request's URI</td></tr>
165 <tr><td><code>REQUEST_URI</code></td>
166 <td>The path part of the request's URI</td></tr>
167 <tr class="odd"><td><code>DOCUMENT_URI</code></td>
168 <td>Same as <code>REQUEST_URI</code></td></tr>
169 <tr><td><code>REQUEST_FILENAME</code></td>
170 <td>The full local filesystem path to the file or script matching the
171 request, if this has already been determined by the server at the
172 time <code>REQUEST_FILENAME</code> is referenced. Otherwise, such
173 as when used in virtual host context, the same value as
174 <code>REQUEST_URI</code> </td></tr>
175 <tr class="odd"><td><code>SCRIPT_FILENAME</code></td>
176 <td>Same as <code>REQUEST_FILENAME</code></td></tr>
177 <tr><td><code>LAST_MODIFIED</code></td>
178 <td>The date and time of last modification of the file in the format
179 <code>20101231235959</code>, if this has already been determined by
180 the server at the time <code>LAST_MODIFIED</code> is referenced.
182 <tr class="odd"><td><code>SCRIPT_USER</code></td>
183 <td>The user name of the owner of the script.</td></tr>
184 <tr><td><code>SCRIPT_GROUP</code></td>
185 <td>The group name of the group of the script.</td></tr>
186 <tr class="odd"><td><code>PATH_INFO</code></td>
187 <td>The trailing path name information, see
188 <code class="directive"><a href="./mod/core.html#acceptpathinfo">AcceptPathInfo</a></code></td></tr>
189 <tr><td><code>QUERY_STRING</code></td>
190 <td>The query string of the current request</td></tr>
191 <tr class="odd"><td><code>IS_SUBREQ</code></td>
192 <td>"<code>true</code>" if the current request is a subrequest,
193 "<code>false</code>" otherwise</td></tr>
194 <tr><td><code>THE_REQUEST</code></td>
195 <td>The complete request line (e.g.,
196 "<code>GET /index.html HTTP/1.1</code>")</td></tr>
197 <tr class="odd"><td><code>REMOTE_ADDR</code></td>
198 <td>The IP address of the remote host</td></tr>
199 <tr><td><code>REMOTE_HOST</code></td>
200 <td>The host name of the remote host</td></tr>
201 <tr class="odd"><td><code>REMOTE_USER</code></td>
202 <td>The name of the authenticated user, if any (not available during <code class="directive"><If></code>)</td></tr>
203 <tr><td><code>REMOTE_IDENT</code></td>
204 <td>The user name set by <code class="module"><a href="./mod/mod_ident.html">mod_ident</a></code></td></tr>
205 <tr class="odd"><td><code>SERVER_NAME</code></td>
206 <td>The <code class="directive"><a href="./mod/core.html#servername">ServerName</a></code> of
207 the current vhost</td></tr>
208 <tr><td><code>SERVER_PORT</code></td>
209 <td>The server port of the current vhost, see
210 <code class="directive"><a href="./mod/core.html#servername">ServerName</a></code></td></tr>
211 <tr class="odd"><td><code>SERVER_ADMIN</code></td>
212 <td>The <code class="directive"><a href="./mod/core.html#serveradmin">ServerAdmin</a></code> of
213 the current vhost</td></tr>
214 <tr><td><code>SERVER_PROTOCOL</code></td>
215 <td>The protocol used by the request (e.g. HTTP/1.1). In some types of
216 internal subrequests, this variable has the value
217 <code>INCLUDED</code>.</td></tr>
218 <tr class="odd"><td><code>SERVER_PROTOCOL_VERSION</code></td>
219 <td>A number that encodes the HTTP version of the request:
220 <code>1000 * major + minor</code>. For example, <code>1001</code>
221 corresponds to HTTP/1.1 and <code>9</code> corresponds
222 to HTTP/0.9</td></tr>
223 <tr><td><code>SERVER_PROTOCOL_VERSION_MAJOR</code></td>
224 <td>The major version part of the HTTP version of the request,
225 e.g. <code>1</code> for HTTP/1.0</td></tr>
226 <tr class="odd"><td><code>SERVER_PROTOCOL_VERSION_MINOR</code></td>
227 <td>The minor version part of the HTTP version of the request,
228 e.g. <code>0</code> for HTTP/1.0</td></tr>
229 <tr><td><code>DOCUMENT_ROOT</code></td>
230 <td>The <code class="directive"><a href="./mod/core.html#documentroot">DocumentRoot</a></code> of
231 the current vhost</td></tr>
232 <tr class="odd"><td><code>AUTH_TYPE</code></td>
233 <td>The configured <code class="directive"><a href="./mod/mod_authn_core.html#authtype">AuthType</a></code> (e.g.
234 "<code>basic</code>")</td></tr>
235 <tr><td><code>CONTENT_TYPE</code></td>
236 <td>The content type of the response (not available during <code class="directive"><If></code>)</td></tr>
237 <tr class="odd"><td><code>HANDLER</code></td>
238 <td>The name of the <a href="handler.html">handler</a> creating
239 the response</td></tr>
240 <tr><td><code>HTTP2</code></td>
241 <td>"<code>on</code>" if the request uses http/2,
242 "<code>off</code>" otherwise</td></tr>
243 <tr class="odd"><td><code>HTTPS</code></td>
244 <td>"<code>on</code>" if the request uses https,
245 "<code>off</code>" otherwise</td></tr>
246 <tr><td><code>IPV6</code></td>
247 <td>"<code>on</code>" if the connection uses IPv6,
248 "<code>off</code>" otherwise</td></tr>
249 <tr class="odd"><td><code>REQUEST_STATUS</code></td>
250 <td>The HTTP error status of the request (not available during <code class="directive"><If></code>)</td></tr>
251 <tr><td><code>REQUEST_LOG_ID</code></td>
252 <td>The error log id of the request (see
253 <code class="directive"><a href="./mod/core.html#errorlogformat">ErrorLogFormat</a></code>)</td></tr>
254 <tr class="odd"><td><code>CONN_LOG_ID</code></td>
255 <td>The error log id of the connection (see
256 <code class="directive"><a href="./mod/core.html#errorlogformat">ErrorLogFormat</a></code>)</td></tr>
257 <tr><td><code>CONN_REMOTE_ADDR</code></td>
258 <td>The peer IP address of the connection (see the
259 <code class="module"><a href="./mod/mod_remoteip.html">mod_remoteip</a></code> module)</td></tr>
260 <tr class="odd"><td><code>CONTEXT_PREFIX</code></td>
262 <tr><td><code>CONTEXT_DOCUMENT_ROOT</code></td>
266 <p>Misc variables</p>
268 <table class="bordered"><tr class="header"><th>Name</th><th>Description</th></tr>
269 <tr><td><code>TIME_YEAR</code></td>
270 <td>The current year (e.g. <code>2010</code>)</td></tr>
271 <tr class="odd"><td><code>TIME_MON</code></td>
272 <td>The current month (<code>1</code>, ..., <code>12</code>)</td></tr>
273 <tr><td><code>TIME_DAY</code></td>
274 <td>The current day of the month</td></tr>
275 <tr class="odd"><td><code>TIME_HOUR</code></td>
276 <td>The hour part of the current time
277 (<code>0</code>, ..., <code>23</code>)</td></tr>
278 <tr><td><code>TIME_MIN</code></td>
279 <td>The minute part of the current time </td></tr>
280 <tr class="odd"><td><code>TIME_SEC</code></td>
281 <td>The second part of the current time </td></tr>
282 <tr><td><code>TIME_WDAY</code></td>
283 <td>The day of the week (starting with <code>0</code>
284 for Sunday)</td></tr>
285 <tr class="odd"><td><code>TIME</code></td>
286 <td>The date and time in the format
287 <code>20101231235959</code></td></tr>
288 <tr><td><code>SERVER_SOFTWARE</code></td>
289 <td>The server version string</td></tr>
290 <tr class="odd"><td><code>API_VERSION</code></td>
291 <td>The date of the API version (module magic number)</td></tr>
294 <p>Some modules register additional variables, see e.g.
295 <code class="module"><a href="./mod/mod_ssl.html">mod_ssl</a></code>.</p>
297 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
298 <div class="section">
299 <h2><a name="binop" id="binop">Binary operators</a></h2>
302 <p>With the exception of some built-in comparison operators, binary
303 operators have the form "<code>-[a-zA-Z][a-zA-Z0-9_]+</code>", i.e. a
304 minus and at least two characters. The name is not case sensitive.
305 Modules may register additional binary operators.</p>
307 <h3><a name="comp" id="comp">Comparison operators</a></h3>
310 <table class="bordered"><tr class="header"><th>Name</th><th>Alternative</th> <th>Description</th></tr>
311 <tr><td><code>==</code></td>
312 <td><code>=</code></td>
313 <td>String equality</td></tr>
314 <tr class="odd"><td><code>!=</code></td>
316 <td>String inequality</td></tr>
317 <tr><td><code><</code></td>
319 <td>String less than</td></tr>
320 <tr class="odd"><td><code><=</code></td>
322 <td>String less than or equal</td></tr>
323 <tr><td><code>></code></td>
325 <td>String greater than</td></tr>
326 <tr class="odd"><td><code>>=</code></td>
328 <td>String greater than or equal</td></tr>
329 <tr><td><code>=~</code></td>
331 <td>String matches the regular expression</td></tr>
332 <tr class="odd"><td><code>!~</code></td>
334 <td>String does not match the regular expression</td></tr>
335 <tr><td><code>-eq</code></td>
336 <td><code>eq</code></td>
337 <td>Integer equality</td></tr>
338 <tr class="odd"><td><code>-ne</code></td>
339 <td><code>ne</code></td>
340 <td>Integer inequality</td></tr>
341 <tr><td><code>-lt</code></td>
342 <td><code>lt</code></td>
343 <td>Integer less than</td></tr>
344 <tr class="odd"><td><code>-le</code></td>
345 <td><code>le</code></td>
346 <td>Integer less than or equal</td></tr>
347 <tr><td><code>-gt</code></td>
348 <td><code>gt</code></td>
349 <td>Integer greater than</td></tr>
350 <tr class="odd"><td><code>-ge</code></td>
351 <td><code>ge</code></td>
352 <td>Integer greater than or equal</td></tr>
356 <h3><a name="binaryother" id="binaryother">Other binary operators</a></h3>
359 <table class="bordered"><tr class="header"><th>Name</th><th>Description</th></tr>
360 <tr><td><code>-ipmatch</code></td>
361 <td>IP address matches address/netmask</td></tr>
362 <tr class="odd"><td><code>-strmatch</code></td>
363 <td>left string matches pattern given by right string (containing
364 wildcards *, ?, [])</td></tr>
365 <tr><td><code>-strcmatch</code></td>
366 <td>same as <code>-strmatch</code>, but case insensitive</td></tr>
367 <tr class="odd"><td><code>-fnmatch</code></td>
368 <td>same as <code>-strmatch</code>, but slashes are not matched by
373 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
374 <div class="section">
375 <h2><a name="unnop" id="unnop">Unary operators</a></h2>
378 <p>Unary operators take one argument and have the form
379 "<code>-[a-zA-Z]</code>", i.e. a minus and one character.
380 The name <em>is</em> case sensitive.
381 Modules may register additional unary operators.</p>
383 <table class="bordered"><tr class="header"><th>Name</th><th>Description</th><th>Restricted</th></tr>
384 <tr><td><code>-d</code></td>
385 <td>The argument is treated as a filename.
386 True if the file exists and is a directory</td><td>yes</td></tr>
387 <tr class="odd"><td><code>-e</code></td>
388 <td>The argument is treated as a filename.
389 True if the file (or dir or special) exists</td><td>yes</td></tr>
390 <tr><td><code>-f</code></td>
391 <td>The argument is treated as a filename.
392 True if the file exists and is regular file</td><td>yes</td></tr>
393 <tr class="odd"><td><code>-s</code></td>
394 <td>The argument is treated as a filename.
395 True if the file exists and is not empty</td><td>yes</td></tr>
396 <tr><td><code>-L</code></td>
397 <td>The argument is treated as a filename.
398 True if the file exists and is symlink</td><td>yes</td></tr>
399 <tr class="odd"><td><code>-h</code></td>
400 <td>The argument is treated as a filename.
401 True if the file exists and is symlink
402 (same as <code>-L</code>)</td><td>yes</td></tr>
403 <tr><td><code>-F</code></td>
404 <td>True if string is a valid file, accessible via all the server's
405 currently-configured access controls for that path. This uses an
406 internal subrequest to do the check, so use it with care - it can
407 impact your server's performance!</td><td /></tr>
408 <tr class="odd"><td><code>-U</code></td>
409 <td>True if string is a valid URL, accessible via all the server's
410 currently-configured access controls for that path. This uses an
411 internal subrequest to do the check, so use it with care - it can
412 impact your server's performance!</td><td /></tr>
413 <tr><td><code>-A</code></td>
414 <td>Alias for <code>-U</code></td><td /></tr>
415 <tr class="odd"><td><code>-n</code></td>
416 <td>True if string is not empty</td><td /></tr>
417 <tr><td><code>-z</code></td>
418 <td>True if string is empty</td><td /></tr>
419 <tr class="odd"><td><code>-T</code></td>
420 <td>False if string is empty, "<code>0</code>", "<code>off</code>",
421 "<code>false</code>", or "<code>no</code>" (case insensitive).
422 True otherwise.</td><td /></tr>
423 <tr><td><code>-R</code></td>
424 <td>Same as "<code>%{REMOTE_ADDR} -ipmatch ...</code>", but more
429 <p>The operators marked as "restricted" are not available in some modules
430 like <code class="module"><a href="./mod/mod_include.html">mod_include</a></code>.</p>
431 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
432 <div class="section">
433 <h2><a name="functions" id="functions">Functions</a></h2>
436 <p>Normal string-valued functions take one string as argument and return
437 a string. Functions names are not case sensitive.
438 Modules may register additional functions.</p>
440 <table class="bordered"><tr class="header"><th>Name</th><th>Description</th><th>Restricted</th></tr>
441 <tr><td><code>req</code>, <code>http</code></td>
442 <td>Get HTTP request header; header names may be added to the Vary
443 header, see below</td><td /></tr>
444 <tr class="odd"><td><code>req_novary</code></td>
445 <td>Same as <code>req</code>, but header names will not be added to the
446 Vary header</td><td /></tr>
447 <tr><td><code>resp</code></td>
448 <td>Get HTTP response header (most response headers will not yet be set
449 during <code class="directive"><If></code>)</td><td /></tr>
450 <tr class="odd"><td><code>reqenv</code></td>
451 <td>Lookup request environment variable (as a shortcut,
452 <code>v</code> can be used too to access
453 variables)</td><td /></tr>
454 <tr><td><code>osenv</code></td>
455 <td>Lookup operating system environment variable</td><td /></tr>
456 <tr class="odd"><td><code>note</code></td>
457 <td>Lookup request note</td><td /></tr>
458 <tr><td><code>env</code></td>
459 <td>Return first match of <code>note</code>, <code>reqenv</code>,
460 <code>osenv</code></td><td /></tr>
461 <tr class="odd"><td><code>tolower</code></td>
462 <td>Convert string to lower case</td><td /></tr>
463 <tr><td><code>toupper</code></td>
464 <td>Convert string to upper case</td><td /></tr>
465 <tr class="odd"><td><code>escape</code></td>
466 <td>Escape special characters in %hex encoding</td><td /></tr>
467 <tr><td><code>unescape</code></td>
468 <td>Unescape %hex encoded string, leaving encoded slashes alone;
469 return empty string if %00 is found</td><td /></tr>
470 <tr class="odd"><td><code>base64</code></td>
471 <td>Encode the string using base64 encoding</td><td /></tr>
472 <tr><td><code>unbase64</code></td>
473 <td>Decode base64 encoded string, return truncated string if 0x00 is
474 found</td><td /></tr>
475 <tr class="odd"><td><code>md5</code></td>
476 <td>Hash the string using MD5, then encode the hash with hexadecimal
477 encoding</td><td /></tr>
478 <tr><td><code>sha1</code></td>
479 <td>Hash the string using SHA1, then encode the hash with hexadecimal
480 encoding</td><td /></tr>
481 <tr class="odd"><td><code>file</code></td>
482 <td>Read contents from a file (including line endings, when present)
483 </td><td>yes</td></tr>
484 <tr><td><code>filemod</code></td>
485 <td>Return last modification time of a file (or 0 if file does not exist
486 or is not regular file)</td><td>yes</td></tr>
487 <tr class="odd"><td><code>filesize</code></td>
488 <td>Return size of a file (or 0 if file does not exist or is not
489 regular file)</td><td>yes</td></tr>
490 <tr><td><code>ldap</code></td>
491 <td>Escape characters as required by LDAP distinguished name escaping
492 (RFC4514) and LDAP filter escaping (RFC4515).</td><td /></tr>
493 <tr class="odd"><td><code>replace</code></td>
494 <td>replace(string, "from", "to") replaces all occurences of "from"
495 in the string with "to".</td><td /></tr>
498 <p>The functions marked as "restricted" are not available in some modules
499 like <code class="module"><a href="./mod/mod_include.html">mod_include</a></code>.</p>
501 <p>When the functions <code>req</code> or <code>http</code> are used,
502 the header name will automatically be added to the Vary header of the
503 HTTP response, except where otherwise noted for the directive accepting
504 the expression. The <code>req_novary</code> function can be used to
505 prevent names from being added to the Vary header.</p>
507 <p>In addition to string-valued functions, there are also
508 list-valued functions which take one string as argument and return a
509 wordlist, i.e. a list of strings. The wordlist can be used with the
510 special <code>-in</code> operator. Functions names are not case
511 sensitive. Modules may register additional functions.</p>
513 <p>There are no built-in list-valued functions. <code class="module"><a href="./mod/mod_ssl.html">mod_ssl</a></code>
514 provides <code>PeerExtList</code>. See the description of
515 <code class="directive"><a href="./mod/mod_ssl.html#sslrequire">SSLRequire</a></code> for details
516 (but <code>PeerExtList</code> is also usable outside
517 of <code class="directive"><a href="./mod/mod_ssl.html#sslrequire">SSLRequire</a></code>).</p>
519 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
520 <div class="section">
521 <h2><a name="examples" id="examples">Example expressions</a></h2>
524 <p>The following examples show how expressions might be used to
525 evaluate requests:</p>
528 <pre class="prettyprint lang-config"># Compare the host name to example.com and redirect to www.example.com if it matches
529 <If "%{HTTP_HOST} == 'example.com'">
530 Redirect permanent "/" "http://www.example.com/"
533 # Force text/plain if requesting a file with the query string contains 'forcetext'
534 <If "%{QUERY_STRING} =~ /forcetext/">
538 # Only allow access to this content during business hours
539 <Directory "/foo/bar/business">
540 Require expr %{TIME_HOUR} -gt 9 && %{TIME_HOUR} -lt 17
543 # Check a HTTP header for a list of values
544 <If "%{HTTP:X-example-header} in { 'foo', 'bar', 'baz' }">
545 Header set matched true
548 # Check an environment variable for a regular expression, negated.
549 <If "! reqenv('REDIRECT_FOO') =~ /bar/">
550 Header set matched true
553 # Check result of URI mapping by running in Directory context with -f
554 <Directory "/var/www">
555 AddEncoding x-gzip gz
556 <If "-f '%{REQUEST_FILENAME}.unzipme' && ! %{HTTP:Accept-Encoding} =~ /gzip/">
557 SetOutputFilter INFLATE
561 # Check against the client IP
562 <If "-R '192.168.1.0/24'">
563 Header set matched true
566 # Function examples in boolean context
567 <If "md5('foo') == 'acbd18db4cc2f85cedef654fccc4a4d8'">
568 Header set checksum-matched true
570 <If "md5('foo') == replace('md5:XXXd18db4cc2f85cedef654fccc4a4d8', 'md5:XXX', 'acb')">
571 Header set checksum-matched-2 true
574 # Function example in string context
575 Header set foo-checksum "expr=%{md5:foo}"
577 # This delays the evaluation of the condition clause compared to <If>
578 Header always set CustomHeader my-value "expr=%{REQUEST_URI} =~ m#^/special_path.php$#"</pre>
580 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
581 <div class="section">
582 <h2><a name="other" id="other">Other</a></h2>
585 <table class="bordered"><tr class="header"><th>Name</th><th>Alternative</th> <th>Description</th></tr>
586 <tr><td><code>-in</code></td>
587 <td><code>in</code></td>
588 <td>string contained in wordlist</td></tr>
589 <tr class="odd"><td><code>/regexp/</code></td>
590 <td><code>m#regexp#</code></td>
591 <td>Regular expression (the second form allows different
592 delimiters than /)</td></tr>
593 <tr><td><code>/regexp/i</code></td>
594 <td><code>m#regexp#i</code></td>
595 <td>Case insensitive regular expression</td></tr>
596 <tr class="odd"><td><code>$0 ... $9</code></td>
598 <td>Regular expression backreferences</td></tr>
601 <h3><a name="rebackref" id="rebackref">Regular expression backreferences</a></h3>
603 <p>The strings <code>$0</code> ... <code>$9</code> allow to reference
604 the capture groups from a previously executed, successfully
605 matching regular expressions. They can normally only be used in the
606 same expression as the matching regex, but some modules allow special
610 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
611 <div class="section">
612 <h2><a name="sslrequire" id="sslrequire">Comparison with SSLRequire</a></h2>
614 <p>The <em>ap_expr</em> syntax is mostly a superset of the syntax of the
615 deprecated <code class="directive"><a href="./mod/mod_ssl.html#sslrequire">SSLRequire</a></code> directive.
616 The differences are described in <code class="directive"><a href="./mod/mod_ssl.html#sslrequire">SSLRequire</a></code>'s documentation.</p>
617 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
618 <div class="section">
619 <h2><a name="compatibility" id="compatibility">Version History</a></h2>
621 <p>The <code>req_novary</code> <a href="#functions">function</a>
622 is available for versions 2.4.4 and later.</p>
623 <p>The <code>SERVER_PROTOCOL_VERSION</code>,
624 <code>SERVER_PROTOCOL_VERSION_MAJOR</code> and
625 <code>SERVER_PROTOCOL_VERSION_MINOR</code>
626 <a href="#vars">variables</a>
627 are available for versions 2.5.0 and later.</p>
629 <div class="bottomlang">
630 <p><span>Available Languages: </span><a href="./en/expr.html" title="English"> en </a> |
631 <a href="./fr/expr.html" hreflang="fr" rel="alternate" title="Français"> fr </a></p>
632 </div><div class="top"><a href="#page-header"><img src="./images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed again by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Freenode, or sent to our <a href="http://httpd.apache.org/lists.html">mailing lists</a>.</div>
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