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18 <p class="apache">Apache HTTP Server Version 2.5</p>
19 <img alt="" src="./images/feather.gif" /></div>
20 <div class="up"><a href="./"><img title="<-" alt="<-" src="./images/left.gif" /></a></div>
22 <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>
24 <p><span>Available Languages: </span><a href="./en/expr.html" title="English"> en </a> |
25 <a href="./fr/expr.html" hreflang="fr" rel="alternate" title="Français"> fr </a></p>
28 <p>Historically, there are several syntax variants for expressions
29 used to express a condition in the different modules of the Apache
30 HTTP Server. There is some ongoing effort to only use a single
31 variant, called <em>ap_expr</em>, for all configuration directives.
32 This document describes the <em>ap_expr</em> expression parser.
34 <p>The <em>ap_expr</em> expression is intended to replace most other
35 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
36 by <a href="mod/mod_authz_core.html#reqexpr">Require expr</a>. </p>
38 <div id="quickview"><ul id="toc"><li><img alt="" src="./images/down.gif" /> <a href="#grammar">Grammar in Backus-Naur Form notation</a></li>
39 <li><img alt="" src="./images/down.gif" /> <a href="#vars">Variables</a></li>
40 <li><img alt="" src="./images/down.gif" /> <a href="#binop">Binary operators</a></li>
41 <li><img alt="" src="./images/down.gif" /> <a href="#unnop">Unary operators</a></li>
42 <li><img alt="" src="./images/down.gif" /> <a href="#functions">Functions</a></li>
43 <li><img alt="" src="./images/down.gif" /> <a href="#examples">Example expressions</a></li>
44 <li><img alt="" src="./images/down.gif" /> <a href="#other">Other</a></li>
45 <li><img alt="" src="./images/down.gif" /> <a href="#sslrequire">Comparison with SSLRequire</a></li>
46 <li><img alt="" src="./images/down.gif" /> <a href="#compatibility">Version History</a></li>
47 </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><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></ul><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
48 <div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
50 <h2><a name="grammar" id="grammar">Grammar in Backus-Naur Form notation</a></h2>
52 <p><a href="http://en.wikipedia.org/wiki/Backus%E2%80%93Naur_Form">Backus-Naur
53 Form</a> (BNF) is a notation technique for context-free grammars,
54 often used to describe the syntax of languages used in computing.
55 In most cases, expressions are used to express boolean values.
56 For these, the starting point in the BNF is <code>expr</code>.
57 However, a few directives like <code class="directive"><a href="./mod/mod_log_debug.html#logmessage">LogMessage</a></code> accept expressions
58 that evaluate to a string value. For those, the starting point in
59 the BNF is <code>string</code>.
62 <pre>expr ::= "<strong>true</strong>" | "<strong>false</strong>"
63 | "<strong>!</strong>" expr
64 | expr "<strong>&&</strong>" expr
65 | expr "<strong>||</strong>" expr
66 | "<strong>(</strong>" expr "<strong>)</strong>"
73 | word "<strong>in</strong>" "<strong>{</strong>" wordlist "<strong>}</strong>"
74 | word "<strong>in</strong>" listfunction
75 | word "<strong>=~</strong>" regex
76 | word "<strong>!~</strong>" regex
79 stringcomp ::= word "<strong>==</strong>" word
80 | word "<strong>!=</strong>" word
81 | word "<strong><</strong>" word
82 | word "<strong><=</strong>" word
83 | word "<strong>></strong>" word
84 | word "<strong>>=</strong>" word
86 integercomp ::= word "<strong>-eq</strong>" word | word "<strong>eq</strong>" word
87 | word "<strong>-ne</strong>" word | word "<strong>ne</strong>" word
88 | word "<strong>-lt</strong>" word | word "<strong>lt</strong>" word
89 | word "<strong>-le</strong>" word | word "<strong>le</strong>" word
90 | word "<strong>-gt</strong>" word | word "<strong>gt</strong>" word
91 | word "<strong>-ge</strong>" word | word "<strong>ge</strong>" word
94 | wordlist "<strong>,</strong>" word
96 word ::= word "<strong>.</strong>" word
98 | "<strong>'</strong>" string "<strong>'</strong>"
99 | "<strong>"</strong>" string "<strong>"</strong>"
104 string ::= stringpart
107 stringpart ::= cstring
114 variable ::= "<strong>%{</strong>" varname "<strong>}</strong>"
115 | "<strong>%{</strong>" funcname "<strong>:</strong>" funcargs "<strong>}</strong>"
117 rebackref ::= "<strong>$</strong>" [0-9]
119 function ::= funcname "<strong>(</strong>" wordlist "<strong>)</strong>"
121 listfunction ::= listfuncname "<strong>(</strong>" word "<strong>)</strong>"</pre>
124 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
125 <div class="section">
126 <h2><a name="vars" id="vars">Variables</a></h2>
129 <p>The expression parser provides a number of variables of the form
130 <code>%{HTTP_HOST}</code>. Note that the value of a variable may depend
131 on the phase of the request processing in which it is evaluated. For
132 example, an expression used in an <code class="directive"><If ></code>
133 directive is evaluated before authentication is done. Therefore,
134 <code>%{REMOTE_USER}</code> will not be set in this case.</p>
136 <p>The following variables provide the values of the named HTTP request
137 headers. The values of other headers can be obtained with the
138 <code>req</code> <a href="#functions">function</a>. Using these
139 variables may cause the header name to be added to the Vary
140 header of the HTTP response, except where otherwise noted for the
141 directive accepting the expression. The <code>req_novary</code>
142 <a href="#functions">function</a> may be used to circumvent this
145 <table class="bordered"><tr class="header"><th>Name</th></tr>
146 <tr><td><code>HTTP_ACCEPT</code></td></tr>
147 <tr class="odd"><td><code>HTTP_COOKIE</code></td></tr>
148 <tr><td><code>HTTP_FORWARDED</code></td></tr>
149 <tr class="odd"><td><code>HTTP_HOST</code></td></tr>
150 <tr><td><code>HTTP_PROXY_CONNECTION</code></td></tr>
151 <tr class="odd"><td><code>HTTP_REFERER</code></td></tr>
152 <tr><td><code>HTTP_USER_AGENT</code></td></tr>
155 <p>Other request related variables</p>
157 <table class="bordered"><tr class="header"><th>Name</th><th>Description</th></tr>
158 <tr><td><code>REQUEST_METHOD</code></td>
159 <td>The HTTP method of the incoming request (e.g.
160 <code>GET</code>)</td></tr>
161 <tr class="odd"><td><code>REQUEST_SCHEME</code></td>
162 <td>The scheme part of the request's URI</td></tr>
163 <tr><td><code>REQUEST_URI</code></td>
164 <td>The path part of the request's URI</td></tr>
165 <tr class="odd"><td><code>DOCUMENT_URI</code></td>
166 <td>Same as <code>REQUEST_URI</code></td></tr>
167 <tr><td><code>REQUEST_FILENAME</code></td>
168 <td>The full local filesystem path to the file or script matching the
169 request, if this has already been determined by the server at the
170 time <code>REQUEST_FILENAME</code> is referenced. Otherwise, such
171 as when used in virtual host context, the same value as
172 <code>REQUEST_URI</code> </td></tr>
173 <tr class="odd"><td><code>SCRIPT_FILENAME</code></td>
174 <td>Same as <code>REQUEST_FILENAME</code></td></tr>
175 <tr><td><code>LAST_MODIFIED</code></td>
176 <td>The date and time of last modification of the file in the format
177 <code>20101231235959</code>, if this has already been determined by
178 the server at the time <code>LAST_MODIFIED</code> is referenced.
180 <tr class="odd"><td><code>SCRIPT_USER</code></td>
181 <td>The user name of the owner of the script.</td></tr>
182 <tr><td><code>SCRIPT_GROUP</code></td>
183 <td>The group name of the group of the script.</td></tr>
184 <tr class="odd"><td><code>PATH_INFO</code></td>
185 <td>The trailing path name information, see
186 <code class="directive"><a href="./mod/core.html#acceptpathinfo">AcceptPathInfo</a></code></td></tr>
187 <tr><td><code>QUERY_STRING</code></td>
188 <td>The query string of the current request</td></tr>
189 <tr class="odd"><td><code>IS_SUBREQ</code></td>
190 <td>"<code>true</code>" if the current request is a subrequest,
191 "<code>false</code>" otherwise</td></tr>
192 <tr><td><code>THE_REQUEST</code></td>
193 <td>The complete request line (e.g.,
194 "<code>GET /index.html HTTP/1.1</code>")</td></tr>
195 <tr class="odd"><td><code>REMOTE_ADDR</code></td>
196 <td>The IP address of the remote host</td></tr>
197 <tr><td><code>REMOTE_HOST</code></td>
198 <td>The host name of the remote host</td></tr>
199 <tr class="odd"><td><code>REMOTE_USER</code></td>
200 <td>The name of the authenticated user, if any (not available during <code class="directive"><If></code>)</td></tr>
201 <tr><td><code>REMOTE_IDENT</code></td>
202 <td>The user name set by <code class="module"><a href="./mod/mod_ident.html">mod_ident</a></code></td></tr>
203 <tr class="odd"><td><code>SERVER_NAME</code></td>
204 <td>The <code class="directive"><a href="./mod/core.html#servername">ServerName</a></code> of
205 the current vhost</td></tr>
206 <tr><td><code>SERVER_PORT</code></td>
207 <td>The server port of the current vhost, see
208 <code class="directive"><a href="./mod/core.html#servername">ServerName</a></code></td></tr>
209 <tr class="odd"><td><code>SERVER_ADMIN</code></td>
210 <td>The <code class="directive"><a href="./mod/core.html#serveradmin">ServerAdmin</a></code> of
211 the current vhost</td></tr>
212 <tr><td><code>SERVER_PROTOCOL</code></td>
213 <td>The protocol used by the request (e.g. HTTP/1.1). In some types of
214 internal subrequests, this variable has the value
215 <code>INCLUDED</code>.</td></tr>
216 <tr class="odd"><td><code>SERVER_PROTOCOL_VERSION</code></td>
217 <td>A number that encodes the HTTP version of the request:
218 <code>1000 * major + minor</code>. For example, <code>1001</code>
219 corresponds to HTTP/1.1 and <code>9</code> corresponds
220 to HTTP/0.9</td></tr>
221 <tr><td><code>SERVER_PROTOCOL_VERSION_MAJOR</code></td>
222 <td>The major version part of the HTTP version of the request,
223 e.g. <code>1</code> for HTTP/1.0</td></tr>
224 <tr class="odd"><td><code>SERVER_PROTOCOL_VERSION_MINOR</code></td>
225 <td>The minor version part of the HTTP version of the request,
226 e.g. <code>0</code> for HTTP/1.0</td></tr>
227 <tr><td><code>DOCUMENT_ROOT</code></td>
228 <td>The <code class="directive"><a href="./mod/core.html#documentroot">DocumentRoot</a></code> of
229 the current vhost</td></tr>
230 <tr class="odd"><td><code>AUTH_TYPE</code></td>
231 <td>The configured <code class="directive"><a href="./mod/mod_authn_core.html#authtype">AuthType</a></code> (e.g.
232 "<code>basic</code>")</td></tr>
233 <tr><td><code>CONTENT_TYPE</code></td>
234 <td>The content type of the response (not available during <code class="directive"><If></code>)</td></tr>
235 <tr class="odd"><td><code>HANDLER</code></td>
236 <td>The name of the <a href="handler.html">handler</a> creating
237 the response</td></tr>
238 <tr><td><code>HTTPS</code></td>
239 <td>"<code>on</code>" if the request uses https,
240 "<code>off</code>" otherwise</td></tr>
241 <tr class="odd"><td><code>IPV6</code></td>
242 <td>"<code>on</code>" if the connection uses IPv6,
243 "<code>off</code>" otherwise</td></tr>
244 <tr><td><code>REQUEST_STATUS</code></td>
245 <td>The HTTP error status of the request (not available during <code class="directive"><If></code>)</td></tr>
246 <tr class="odd"><td><code>REQUEST_LOG_ID</code></td>
247 <td>The error log id of the request (see
248 <code class="directive"><a href="./mod/core.html#errorlogformat">ErrorLogFormat</a></code>)</td></tr>
249 <tr><td><code>CONN_LOG_ID</code></td>
250 <td>The error log id of the connection (see
251 <code class="directive"><a href="./mod/core.html#errorlogformat">ErrorLogFormat</a></code>)</td></tr>
252 <tr class="odd"><td><code>CONN_REMOTE_ADDR</code></td>
253 <td>The peer IP address of the connection (see the
254 <code class="module"><a href="./mod/mod_remoteip.html">mod_remoteip</a></code> module)</td></tr>
255 <tr><td><code>CONTEXT_PREFIX</code></td>
257 <tr class="odd"><td><code>CONTEXT_DOCUMENT_ROOT</code></td>
261 <p>Misc variables</p>
263 <table class="bordered"><tr class="header"><th>Name</th><th>Description</th></tr>
264 <tr><td><code>TIME_YEAR</code></td>
265 <td>The current year (e.g. <code>2010</code>)</td></tr>
266 <tr class="odd"><td><code>TIME_MON</code></td>
267 <td>The current month (<code>1</code>, ..., <code>12</code>)</td></tr>
268 <tr><td><code>TIME_DAY</code></td>
269 <td>The current day of the month</td></tr>
270 <tr class="odd"><td><code>TIME_HOUR</code></td>
271 <td>The hour part of the current time
272 (<code>0</code>, ..., <code>23</code>)</td></tr>
273 <tr><td><code>TIME_MIN</code></td>
274 <td>The minute part of the current time </td></tr>
275 <tr class="odd"><td><code>TIME_SEC</code></td>
276 <td>The second part of the current time </td></tr>
277 <tr><td><code>TIME_WDAY</code></td>
278 <td>The day of the week (starting with <code>0</code>
279 for Sunday)</td></tr>
280 <tr class="odd"><td><code>TIME</code></td>
281 <td>The date and time in the format
282 <code>20101231235959</code></td></tr>
283 <tr><td><code>SERVER_SOFTWARE</code></td>
284 <td>The server version string</td></tr>
285 <tr class="odd"><td><code>API_VERSION</code></td>
286 <td>The date of the API version (module magic number)</td></tr>
289 <p>Some modules register additional variables, see e.g.
290 <code class="module"><a href="./mod/mod_ssl.html">mod_ssl</a></code>.</p>
292 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
293 <div class="section">
294 <h2><a name="binop" id="binop">Binary operators</a></h2>
297 <p>With the exception of some built-in comparison operators, binary
298 operators have the form "<code>-[a-zA-Z][a-zA-Z0-9_]+</code>", i.e. a
299 minus and at least two characters. The name is not case sensitive.
300 Modules may register additional binary operators.</p>
302 <h3><a name="comp" id="comp">Comparison operators</a></h3>
305 <table class="bordered"><tr class="header"><th>Name</th><th>Alternative</th> <th>Description</th></tr>
306 <tr><td><code>==</code></td>
307 <td><code>=</code></td>
308 <td>String equality</td></tr>
309 <tr class="odd"><td><code>!=</code></td>
311 <td>String inequality</td></tr>
312 <tr><td><code><</code></td>
314 <td>String less than</td></tr>
315 <tr class="odd"><td><code><=</code></td>
317 <td>String less than or equal</td></tr>
318 <tr><td><code>></code></td>
320 <td>String greater than</td></tr>
321 <tr class="odd"><td><code>>=</code></td>
323 <td>String greater than or equal</td></tr>
324 <tr><td><code>=~</code></td>
326 <td>String matches the regular expression</td></tr>
327 <tr class="odd"><td><code>!~</code></td>
329 <td>String does not match the regular expression</td></tr>
330 <tr><td><code>-eq</code></td>
331 <td><code>eq</code></td>
332 <td>Integer equality</td></tr>
333 <tr class="odd"><td><code>-ne</code></td>
334 <td><code>ne</code></td>
335 <td>Integer inequality</td></tr>
336 <tr><td><code>-lt</code></td>
337 <td><code>lt</code></td>
338 <td>Integer less than</td></tr>
339 <tr class="odd"><td><code>-le</code></td>
340 <td><code>le</code></td>
341 <td>Integer less than or equal</td></tr>
342 <tr><td><code>-gt</code></td>
343 <td><code>gt</code></td>
344 <td>Integer greater than</td></tr>
345 <tr class="odd"><td><code>-ge</code></td>
346 <td><code>ge</code></td>
347 <td>Integer greater than or equal</td></tr>
351 <h3><a name="binaryother" id="binaryother">Other binary operators</a></h3>
354 <table class="bordered"><tr class="header"><th>Name</th><th>Description</th></tr>
355 <tr><td><code>-ipmatch</code></td>
356 <td>IP address matches address/netmask</td></tr>
357 <tr class="odd"><td><code>-strmatch</code></td>
358 <td>left string matches pattern given by right string (containing
359 wildcards *, ?, [])</td></tr>
360 <tr><td><code>-strcmatch</code></td>
361 <td>same as <code>-strmatch</code>, but case insensitive</td></tr>
362 <tr class="odd"><td><code>-fnmatch</code></td>
363 <td>same as <code>-strmatch</code>, but slashes are not matched by
368 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
369 <div class="section">
370 <h2><a name="unnop" id="unnop">Unary operators</a></h2>
373 <p>Unary operators take one argument and have the form
374 "<code>-[a-zA-Z]</code>", i.e. a minus and one character.
375 The name <em>is</em> case sensitive.
376 Modules may register additional unary operators.</p>
378 <table class="bordered"><tr class="header"><th>Name</th><th>Description</th><th>Restricted</th></tr>
379 <tr><td><code>-d</code></td>
380 <td>The argument is treated as a filename.
381 True if the file exists and is a directory</td><td>yes</td></tr>
382 <tr class="odd"><td><code>-e</code></td>
383 <td>The argument is treated as a filename.
384 True if the file (or dir or special) exists</td><td>yes</td></tr>
385 <tr><td><code>-f</code></td>
386 <td>The argument is treated as a filename.
387 True if the file exists and is regular file</td><td>yes</td></tr>
388 <tr class="odd"><td><code>-s</code></td>
389 <td>The argument is treated as a filename.
390 True if the file exists and is not empty</td><td>yes</td></tr>
391 <tr><td><code>-L</code></td>
392 <td>The argument is treated as a filename.
393 True if the file exists and is symlink</td><td>yes</td></tr>
394 <tr class="odd"><td><code>-h</code></td>
395 <td>The argument is treated as a filename.
396 True if the file exists and is symlink
397 (same as <code>-L</code>)</td><td>yes</td></tr>
398 <tr><td><code>-F</code></td>
399 <td>True if string is a valid file, accessible via all the server's
400 currently-configured access controls for that path. This uses an
401 internal subrequest to do the check, so use it with care - it can
402 impact your server's performance!</td><td /></tr>
403 <tr class="odd"><td><code>-U</code></td>
404 <td>True if string is a valid URL, 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><td><code>-A</code></td>
409 <td>Alias for <code>-U</code></td><td /></tr>
410 <tr class="odd"><td><code>-n</code></td>
411 <td>True if string is not empty</td><td /></tr>
412 <tr><td><code>-z</code></td>
413 <td>True if string is empty</td><td /></tr>
414 <tr class="odd"><td><code>-T</code></td>
415 <td>False if string is empty, "<code>0</code>", "<code>off</code>",
416 "<code>false</code>", or "<code>no</code>" (case insensitive).
417 True otherwise.</td><td /></tr>
418 <tr><td><code>-R</code></td>
419 <td>Same as "<code>%{REMOTE_ADDR} -ipmatch ...</code>", but more
424 <p>The operators marked as "restricted" are not available in some modules
425 like <code class="module"><a href="./mod/mod_include.html">mod_include</a></code>.</p>
426 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
427 <div class="section">
428 <h2><a name="functions" id="functions">Functions</a></h2>
431 <p>Normal string-valued functions take one string as argument and return
432 a string. Functions names are not case sensitive.
433 Modules may register additional functions.</p>
435 <table class="bordered"><tr class="header"><th>Name</th><th>Description</th><th>Restricted</th></tr>
436 <tr><td><code>req</code>, <code>http</code></td>
437 <td>Get HTTP request header; header names may be added to the Vary
438 header, see below</td><td /></tr>
439 <tr class="odd"><td><code>req_novary</code></td>
440 <td>Same as <code>req</code>, but header names will not be added to the
441 Vary header</td><td /></tr>
442 <tr><td><code>resp</code></td>
443 <td>Get HTTP response header (most response headers will not yet be set
444 during <code class="directive"><If></code>)</td><td /></tr>
445 <tr class="odd"><td><code>reqenv</code></td>
446 <td>Lookup request environment variable (as a shortcut,
447 <code>v</code> can be used too to access
448 variables)</td><td /></tr>
449 <tr><td><code>osenv</code></td>
450 <td>Lookup operating system environment variable</td><td /></tr>
451 <tr class="odd"><td><code>note</code></td>
452 <td>Lookup request note</td><td /></tr>
453 <tr><td><code>env</code></td>
454 <td>Return first match of <code>note</code>, <code>reqenv</code>,
455 <code>osenv</code></td><td /></tr>
456 <tr class="odd"><td><code>tolower</code></td>
457 <td>Convert string to lower case</td><td /></tr>
458 <tr><td><code>toupper</code></td>
459 <td>Convert string to upper case</td><td /></tr>
460 <tr class="odd"><td><code>escape</code></td>
461 <td>Escape special characters in %hex encoding</td><td /></tr>
462 <tr><td><code>unescape</code></td>
463 <td>Unescape %hex encoded string, leaving encoded slashes alone;
464 return empty string if %00 is found</td><td /></tr>
465 <tr class="odd"><td><code>base64</code></td>
466 <td>Encode the string using base64 encoding</td><td /></tr>
467 <tr><td><code>unbase64</code></td>
468 <td>Decode base64 encoded string, return truncated string if 0x00 is
469 found</td><td /></tr>
470 <tr class="odd"><td><code>md5</code></td>
471 <td>Hash the string using MD5, then encode the hash with hexadecimal
472 encoding</td><td /></tr>
473 <tr><td><code>sha1</code></td>
474 <td>Hash the string using SHA1, then encode the hash with hexadecimal
475 encoding</td><td /></tr>
476 <tr class="odd"><td><code>file</code></td>
477 <td>Read contents from a file (including line endings, when present)
478 </td><td>yes</td></tr>
479 <tr><td><code>filemod</code></td>
480 <td>Return last modification time of a file (or 0 if file does not exist
481 or is not regular file)</td><td>yes</td></tr>
482 <tr class="odd"><td><code>filesize</code></td>
483 <td>Return size of a file (or 0 if file does not exist or is not
484 regular file)</td><td>yes</td></tr>
485 <tr><td><code>ldap</code></td>
486 <td>Escape characters as required by LDAP distinguished name escaping
487 (RFC4514) and LDAP filter escaping (RFC4515).</td><td /></tr>
488 <tr class="odd"><td><code>replace</code></td>
489 <td>replace(string, "from", "to") replaces all occurences of "from"
490 in the string with "to".</td><td /></tr>
493 <p>The functions marked as "restricted" are not available in some modules
494 like <code class="module"><a href="./mod/mod_include.html">mod_include</a></code>.</p>
496 <p>When the functions <code>req</code> or <code>http</code> are used,
497 the header name will automatically be added to the Vary header of the
498 HTTP response, except where otherwise noted for the directive accepting
499 the expression. The <code>req_novary</code> function can be used to
500 prevent names from being added to the Vary header.</p>
502 <p>In addition to string-valued functions, there are also
503 list-valued functions which take one string as argument and return a
504 wordlist, i.e. a list of strings. The wordlist can be used with the
505 special <code>-in</code> operator. Functions names are not case
506 sensitive. Modules may register additional functions.</p>
508 <p>There are no built-in list-valued functions. <code class="module"><a href="./mod/mod_ssl.html">mod_ssl</a></code>
509 provides <code>PeerExtList</code>. See the description of
510 <code class="directive"><a href="./mod/mod_ssl.html#sslrequire">SSLRequire</a></code> for details
511 (but <code>PeerExtList</code> is also usable outside
512 of <code class="directive"><a href="./mod/mod_ssl.html#sslrequire">SSLRequire</a></code>).</p>
514 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
515 <div class="section">
516 <h2><a name="examples" id="examples">Example expressions</a></h2>
519 <p>The following examples show how expressions might be used to
520 evaluate requests:</p>
523 <pre class="prettyprint lang-config"># Compare the host name to example.com and redirect to www.example.com if it matches
524 <If "%{HTTP_HOST} == 'example.com'">
525 Redirect permanent "/" "http://www.example.com/"
528 # Force text/plain if requesting a file with the query string contains 'forcetext'
529 <If "%{QUERY_STRING} =~ /forcetext/">
533 # Only allow access to this content during business hours
534 <Directory "/foo/bar/business">
535 Require expr %{TIME_HOUR} -gt 9 && %{TIME_HOUR} -lt 17
538 # Check a HTTP header for a list of values
539 <If "%{HTTP:X-example-header} in { 'foo', 'bar', 'baz' }">
540 Header set matched true
543 # Check an environment variable for a regular expression, negated.
544 <If "! reqenv('REDIRECT_FOO') =~ /bar/">
545 Header set matched true
548 # Check result of URI mapping by running in Directory context with -f
549 <Directory "/var/www">
550 AddEncoding x-gzip gz
551 <If "-f '%{REQUEST_FILENAME}.unzipme' && ! %{HTTP:Accept-Encoding} =~ /gzip/">
552 SetOutputFilter INFLATE
556 # Function examples in boolean context
557 <If "md5('foo') == 'acbd18db4cc2f85cedef654fccc4a4d8'">
558 Header set checksum-matched true
560 <If "md5('foo') == replace('md5:XXXd18db4cc2f85cedef654fccc4a4d8', 'md5:XXX', 'acb')>
561 Header set checksum-matched-2 true
564 # Function example in string context
565 Header set foo-checksum "expr=%{md5:foo}"</pre>
567 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
568 <div class="section">
569 <h2><a name="other" id="other">Other</a></h2>
572 <table class="bordered"><tr class="header"><th>Name</th><th>Alternative</th> <th>Description</th></tr>
573 <tr><td><code>-in</code></td>
574 <td><code>in</code></td>
575 <td>string contained in wordlist</td></tr>
576 <tr class="odd"><td><code>/regexp/</code></td>
577 <td><code>m#regexp#</code></td>
578 <td>Regular expression (the second form allows different
579 delimiters than /)</td></tr>
580 <tr><td><code>/regexp/i</code></td>
581 <td><code>m#regexp#i</code></td>
582 <td>Case insensitive regular expression</td></tr>
583 <tr class="odd"><td><code>$0 ... $9</code></td>
585 <td>Regular expression backreferences</td></tr>
588 <h3><a name="rebackref" id="rebackref">Regular expression backreferences</a></h3>
590 <p>The strings <code>$0</code> ... <code>$9</code> allow to reference
591 the capture groups from a previously executed, successfully
592 matching regular expressions. They can normally only be used in the
593 same expression as the matching regex, but some modules allow special
597 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
598 <div class="section">
599 <h2><a name="sslrequire" id="sslrequire">Comparison with SSLRequire</a></h2>
601 <p>The <em>ap_expr</em> syntax is mostly a superset of the syntax of the
602 deprecated <code class="directive"><a href="./mod/mod_ssl.html#sslrequire">SSLRequire</a></code> directive.
603 The differences are described in <code class="directive"><a href="./mod/mod_ssl.html#sslrequire">SSLRequire</a></code>'s documentation.</p>
604 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
605 <div class="section">
606 <h2><a name="compatibility" id="compatibility">Version History</a></h2>
608 <p>The <code>req_novary</code> <a href="#functions">function</a>
609 is available for versions 2.4.4 and later.</p>
610 <p>The <code>SERVER_PROTOCOL_VERSION</code>,
611 <code>SERVER_PROTOCOL_VERSION_MAJOR</code> and
612 <code>SERVER_PROTOCOL_VERSION_MINOR</code>
613 <a href="#vars">variables</a>
614 are available for versions 2.5.0 and later.</p>
616 <div class="bottomlang">
617 <p><span>Available Languages: </span><a href="./en/expr.html" title="English"> en </a> |
618 <a href="./fr/expr.html" hreflang="fr" rel="alternate" title="Français"> fr </a></p>
619 </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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