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15 <p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
16 <p class="apache">Apache HTTP Server Version 2.3</p>
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20 <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 2.3</a> > <a href="./">Modules</a></div>
21 <div id="page-content">
22 <div id="preamble"><h1>Apache Core Features</h1>
24 <p><span>Available Languages: </span><a href="../de/mod/core.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
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31 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Core Apache HTTP Server features that are always
33 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>Core</td></tr></table>
35 <div id="quickview"><h3 class="directives">Directives</h3>
37 <li><img alt="" src="../images/down.gif" /> <a href="#acceptfilter">AcceptFilter</a></li>
38 <li><img alt="" src="../images/down.gif" /> <a href="#acceptpathinfo">AcceptPathInfo</a></li>
39 <li><img alt="" src="../images/down.gif" /> <a href="#accessfilename">AccessFileName</a></li>
40 <li><img alt="" src="../images/down.gif" /> <a href="#adddefaultcharset">AddDefaultCharset</a></li>
41 <li><img alt="" src="../images/down.gif" /> <a href="#allowencodedslashes">AllowEncodedSlashes</a></li>
42 <li><img alt="" src="../images/down.gif" /> <a href="#allowoverride">AllowOverride</a></li>
43 <li><img alt="" src="../images/down.gif" /> <a href="#cgimapextension">CGIMapExtension</a></li>
44 <li><img alt="" src="../images/down.gif" /> <a href="#contentdigest">ContentDigest</a></li>
45 <li><img alt="" src="../images/down.gif" /> <a href="#defaulttype">DefaultType</a></li>
46 <li><img alt="" src="../images/down.gif" /> <a href="#define">Define</a></li>
47 <li><img alt="" src="../images/down.gif" /> <a href="#directory"><Directory></a></li>
48 <li><img alt="" src="../images/down.gif" /> <a href="#directorymatch"><DirectoryMatch></a></li>
49 <li><img alt="" src="../images/down.gif" /> <a href="#documentroot">DocumentRoot</a></li>
50 <li><img alt="" src="../images/down.gif" /> <a href="#else"><Else></a></li>
51 <li><img alt="" src="../images/down.gif" /> <a href="#elseif"><ElseIf></a></li>
52 <li><img alt="" src="../images/down.gif" /> <a href="#enablemmap">EnableMMAP</a></li>
53 <li><img alt="" src="../images/down.gif" /> <a href="#enablesendfile">EnableSendfile</a></li>
54 <li><img alt="" src="../images/down.gif" /> <a href="#error">Error</a></li>
55 <li><img alt="" src="../images/down.gif" /> <a href="#errordocument">ErrorDocument</a></li>
56 <li><img alt="" src="../images/down.gif" /> <a href="#errorlog">ErrorLog</a></li>
57 <li><img alt="" src="../images/down.gif" /> <a href="#errorlogformat">ErrorLogFormat</a></li>
58 <li><img alt="" src="../images/down.gif" /> <a href="#extendedstatus">ExtendedStatus</a></li>
59 <li><img alt="" src="../images/down.gif" /> <a href="#fileetag">FileETag</a></li>
60 <li><img alt="" src="../images/down.gif" /> <a href="#files"><Files></a></li>
61 <li><img alt="" src="../images/down.gif" /> <a href="#filesmatch"><FilesMatch></a></li>
62 <li><img alt="" src="../images/down.gif" /> <a href="#forcetype">ForceType</a></li>
63 <li><img alt="" src="../images/down.gif" /> <a href="#gprofdir">GprofDir</a></li>
64 <li><img alt="" src="../images/down.gif" /> <a href="#hostnamelookups">HostnameLookups</a></li>
65 <li><img alt="" src="../images/down.gif" /> <a href="#if"><If></a></li>
66 <li><img alt="" src="../images/down.gif" /> <a href="#ifdefine"><IfDefine></a></li>
67 <li><img alt="" src="../images/down.gif" /> <a href="#ifmodule"><IfModule></a></li>
68 <li><img alt="" src="../images/down.gif" /> <a href="#include">Include</a></li>
69 <li><img alt="" src="../images/down.gif" /> <a href="#keepalive">KeepAlive</a></li>
70 <li><img alt="" src="../images/down.gif" /> <a href="#keepalivetimeout">KeepAliveTimeout</a></li>
71 <li><img alt="" src="../images/down.gif" /> <a href="#limit"><Limit></a></li>
72 <li><img alt="" src="../images/down.gif" /> <a href="#limitexcept"><LimitExcept></a></li>
73 <li><img alt="" src="../images/down.gif" /> <a href="#limitinternalrecursion">LimitInternalRecursion</a></li>
74 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestbody">LimitRequestBody</a></li>
75 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestfields">LimitRequestFields</a></li>
76 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestfieldsize">LimitRequestFieldSize</a></li>
77 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestline">LimitRequestLine</a></li>
78 <li><img alt="" src="../images/down.gif" /> <a href="#limitxmlrequestbody">LimitXMLRequestBody</a></li>
79 <li><img alt="" src="../images/down.gif" /> <a href="#location"><Location></a></li>
80 <li><img alt="" src="../images/down.gif" /> <a href="#locationmatch"><LocationMatch></a></li>
81 <li><img alt="" src="../images/down.gif" /> <a href="#loglevel">LogLevel</a></li>
82 <li><img alt="" src="../images/down.gif" /> <a href="#maxkeepaliverequests">MaxKeepAliveRequests</a></li>
83 <li><img alt="" src="../images/down.gif" /> <a href="#mutex">Mutex</a></li>
84 <li><img alt="" src="../images/down.gif" /> <a href="#namevirtualhost">NameVirtualHost</a></li>
85 <li><img alt="" src="../images/down.gif" /> <a href="#options">Options</a></li>
86 <li><img alt="" src="../images/down.gif" /> <a href="#protocol">Protocol</a></li>
87 <li><img alt="" src="../images/down.gif" /> <a href="#rlimitcpu">RLimitCPU</a></li>
88 <li><img alt="" src="../images/down.gif" /> <a href="#rlimitmem">RLimitMEM</a></li>
89 <li><img alt="" src="../images/down.gif" /> <a href="#rlimitnproc">RLimitNPROC</a></li>
90 <li><img alt="" src="../images/down.gif" /> <a href="#scriptinterpretersource">ScriptInterpreterSource</a></li>
91 <li><img alt="" src="../images/down.gif" /> <a href="#seerequesttail">SeeRequestTail</a></li>
92 <li><img alt="" src="../images/down.gif" /> <a href="#serveradmin">ServerAdmin</a></li>
93 <li><img alt="" src="../images/down.gif" /> <a href="#serveralias">ServerAlias</a></li>
94 <li><img alt="" src="../images/down.gif" /> <a href="#servername">ServerName</a></li>
95 <li><img alt="" src="../images/down.gif" /> <a href="#serverpath">ServerPath</a></li>
96 <li><img alt="" src="../images/down.gif" /> <a href="#serverroot">ServerRoot</a></li>
97 <li><img alt="" src="../images/down.gif" /> <a href="#serversignature">ServerSignature</a></li>
98 <li><img alt="" src="../images/down.gif" /> <a href="#servertokens">ServerTokens</a></li>
99 <li><img alt="" src="../images/down.gif" /> <a href="#sethandler">SetHandler</a></li>
100 <li><img alt="" src="../images/down.gif" /> <a href="#setinputfilter">SetInputFilter</a></li>
101 <li><img alt="" src="../images/down.gif" /> <a href="#setoutputfilter">SetOutputFilter</a></li>
102 <li><img alt="" src="../images/down.gif" /> <a href="#timeout">TimeOut</a></li>
103 <li><img alt="" src="../images/down.gif" /> <a href="#traceenable">TraceEnable</a></li>
104 <li><img alt="" src="../images/down.gif" /> <a href="#undefine">UnDefine</a></li>
105 <li><img alt="" src="../images/down.gif" /> <a href="#usecanonicalname">UseCanonicalName</a></li>
106 <li><img alt="" src="../images/down.gif" /> <a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></li>
107 <li><img alt="" src="../images/down.gif" /> <a href="#virtualhost"><VirtualHost></a></li>
111 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
112 <div class="directive-section"><h2><a name="AcceptFilter" id="AcceptFilter">AcceptFilter</a> <a name="acceptfilter" id="acceptfilter">Directive</a></h2>
113 <table class="directive">
114 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures optimizations for a Protocol's Listener Sockets</td></tr>
115 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AcceptFilter <var>protocol</var> <var>accept_filter</var></code></td></tr>
116 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
117 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
118 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
119 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache httpd 2.1.5 and later.
120 On Windows from Apache httpd 2.3.3 and later.</td></tr>
122 <p>This directive enables operating system specific optimizations for a
123 listening socket by the <code class="directive">Protocol</code>type.
124 The basic premise is for the kernel to not send a socket to the server
125 process until either data is received or an entire HTTP Request is buffered.
126 Only <a href="http://www.freebsd.org/cgi/man.cgi?query=accept_filter&sektion=9">
127 FreeBSD's Accept Filters</a>, Linux's more primitive
128 <code>TCP_DEFER_ACCEPT</code>, and Windows' optimized AcceptEx()
129 are currently supported.</p>
131 <p>Using <code>none</code> for an argument will disable any accept filters
132 for that protocol. This is useful for protocols that require a server
133 send data first, such as <code>ftp:</code> or <code>nntp</code>:</p>
134 <div class="example"><p><code>AcceptFilter nntp none</code></p></div>
136 <p>The default protocol names are <code>https</code> for port 443
137 and <code>http</code> for all other ports. To specify another protocol
138 is being used with a listening port, add the <var>protocol</var>
139 argument to the <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code>
142 <p>The default values on FreeBSD are:</p>
143 <div class="example"><p><code>
144 AcceptFilter http httpready <br />
145 AcceptFilter https dataready
148 <p>The <code>httpready</code> accept filter buffers entire HTTP requests at
149 the kernel level. Once an entire request is received, the kernel then
150 sends it to the server. See the
151 <a href="http://www.freebsd.org/cgi/man.cgi?query=accf_http&sektion=9">
152 accf_http(9)</a> man page for more details. Since HTTPS requests are
153 encrypted only the <a href="http://www.freebsd.org/cgi/man.cgi?query=accf_data&sektion=9">
154 accf_data(9)</a> filter is used.</p>
156 <p>The default values on Linux are:</p>
157 <div class="example"><p><code>
158 AcceptFilter http data <br />
159 AcceptFilter https data
162 <p>Linux's <code>TCP_DEFER_ACCEPT</code> does not support buffering http
163 requests. Any value besides <code>none</code> will enable
164 <code>TCP_DEFER_ACCEPT</code> on that listener. For more details
166 <a href="http://homepages.cwi.nl/~aeb/linux/man2html/man7/tcp.7.html">
167 tcp(7)</a> man page.</p>
169 <p>The default values on Windows are:</p>
170 <div class="example"><p><code>
171 AcceptFilter http data <br />
172 AcceptFilter https data
175 <p>Window's mpm_winnt interprets the AcceptFilter to toggle the AcceptEx()
176 API, and does not support http protocol buffering. There are two values
177 which utilize the Windows AcceptEx() API and will recycle network
178 sockets between connections. <code>data</code> waits until data has
179 been transmitted as documented above, and the initial data buffer and
180 network endpoint addresses are all retrieved from the single AcceptEx()
181 invocation. <code>connect</code> will use the AcceptEx() API, also
182 retrieve the network endpoint addresses, but like <code>none</code>
183 the <code>connect</code> option does not wait for the initial data
186 <p>On Windows, <code>none</code> uses accept() rather than AcceptEx()
187 and will not recycle sockets between connections. This is useful for
188 network adapters with broken driver support, as well as some virtual
189 network providers such as vpn drivers, or spam, virus or spyware
195 <li><code class="directive">Protocol</code></li>
198 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
199 <div class="directive-section"><h2><a name="AcceptPathInfo" id="AcceptPathInfo">AcceptPathInfo</a> <a name="acceptpathinfo" id="acceptpathinfo">Directive</a></h2>
200 <table class="directive">
201 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Resources accept trailing pathname information</td></tr>
202 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AcceptPathInfo On|Off|Default</code></td></tr>
203 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AcceptPathInfo Default</code></td></tr>
204 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
205 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
206 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
207 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
208 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache httpd 2.0.30 and later</td></tr>
211 <p>This directive controls whether requests that contain trailing
212 pathname information that follows an actual filename (or
213 non-existent file in an existing directory) will be accepted or
214 rejected. The trailing pathname information can be made
215 available to scripts in the <code>PATH_INFO</code> environment
218 <p>For example, assume the location <code>/test/</code> points to
219 a directory that contains only the single file
220 <code>here.html</code>. Then requests for
221 <code>/test/here.html/more</code> and
222 <code>/test/nothere.html/more</code> both collect
223 <code>/more</code> as <code>PATH_INFO</code>.</p>
225 <p>The three possible arguments for the
226 <code class="directive">AcceptPathInfo</code> directive are:</p>
228 <dt><code>Off</code></dt><dd>A request will only be accepted if it
229 maps to a literal path that exists. Therefore a request with
230 trailing pathname information after the true filename such as
231 <code>/test/here.html/more</code> in the above example will return
232 a 404 NOT FOUND error.</dd>
234 <dt><code>On</code></dt><dd>A request will be accepted if a
235 leading path component maps to a file that exists. The above
236 example <code>/test/here.html/more</code> will be accepted if
237 <code>/test/here.html</code> maps to a valid file.</dd>
239 <dt><code>Default</code></dt><dd>The treatment of requests with
240 trailing pathname information is determined by the <a href="../handler.html">handler</a> responsible for the request.
241 The core handler for normal files defaults to rejecting
242 <code>PATH_INFO</code> requests. Handlers that serve scripts, such as <a href="mod_cgi.html">cgi-script</a> and <a href="mod_isapi.html">isapi-handler</a>, generally accept
243 <code>PATH_INFO</code> by default.</dd>
246 <p>The primary purpose of the <code>AcceptPathInfo</code>
247 directive is to allow you to override the handler's choice of
248 accepting or rejecting <code>PATH_INFO</code>. This override is required,
249 for example, when you use a <a href="../filter.html">filter</a>, such
250 as <a href="mod_include.html">INCLUDES</a>, to generate content
251 based on <code>PATH_INFO</code>. The core handler would usually reject
252 the request, so you can use the following configuration to enable
255 <div class="example"><p><code>
256 <Files "mypaths.shtml"><br />
257 <span class="indent">
258 Options +Includes<br />
259 SetOutputFilter INCLUDES<br />
260 AcceptPathInfo On<br />
267 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
268 <div class="directive-section"><h2><a name="AccessFileName" id="AccessFileName">AccessFileName</a> <a name="accessfilename" id="accessfilename">Directive</a></h2>
269 <table class="directive">
270 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Name of the distributed configuration file</td></tr>
271 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AccessFileName <var>filename</var> [<var>filename</var>] ...</code></td></tr>
272 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AccessFileName .htaccess</code></td></tr>
273 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
274 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
275 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
277 <p>While processing a request the server looks for
278 the first existing configuration file from this list of names in
279 every directory of the path to the document, if distributed
280 configuration files are <a href="#allowoverride">enabled for that
281 directory</a>. For example:</p>
283 <div class="example"><p><code>
287 <p>before returning the document
288 <code>/usr/local/web/index.html</code>, the server will read
289 <code>/.acl</code>, <code>/usr/.acl</code>,
290 <code>/usr/local/.acl</code> and <code>/usr/local/web/.acl</code>
291 for directives, unless they have been disabled with</p>
293 <div class="example"><p><code>
294 <Directory /><br />
295 <span class="indent">
296 AllowOverride None<br />
303 <li><code class="directive"><a href="#allowoverride">AllowOverride</a></code></li>
304 <li><a href="../configuring.html">Configuration Files</a></li>
305 <li><a href="../howto/htaccess.html">.htaccess Files</a></li>
308 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
309 <div class="directive-section"><h2><a name="AddDefaultCharset" id="AddDefaultCharset">AddDefaultCharset</a> <a name="adddefaultcharset" id="adddefaultcharset">Directive</a></h2>
310 <table class="directive">
311 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Default charset parameter to be added when a response
312 content-type is <code>text/plain</code> or <code>text/html</code></td></tr>
313 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AddDefaultCharset On|Off|<var>charset</var></code></td></tr>
314 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AddDefaultCharset Off</code></td></tr>
315 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
316 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
317 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
318 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
320 <p>This directive specifies a default value for the media type
321 charset parameter (the name of a character encoding) to be added
322 to a response if and only if the response's content-type is either
323 <code>text/plain</code> or <code>text/html</code>. This should override
324 any charset specified in the body of the response via a <code>META</code>
325 element, though the exact behavior is often dependent on the user's client
326 configuration. A setting of <code>AddDefaultCharset Off</code>
327 disables this functionality. <code>AddDefaultCharset On</code> enables
328 a default charset of <code>iso-8859-1</code>. Any other value is assumed
329 to be the <var>charset</var> to be used, which should be one of the
330 <a href="http://www.iana.org/assignments/character-sets">IANA registered
331 charset values</a> for use in Internet media types (MIME types).
334 <div class="example"><p><code>
335 AddDefaultCharset utf-8
338 <p><code class="directive">AddDefaultCharset</code> should only be used when all
339 of the text resources to which it applies are known to be in that
340 character encoding and it is too inconvenient to label their charset
341 individually. One such example is to add the charset parameter
342 to resources containing generated content, such as legacy CGI
343 scripts, that might be vulnerable to cross-site scripting attacks
344 due to user-provided data being included in the output. Note, however,
345 that a better solution is to just fix (or delete) those scripts, since
346 setting a default charset does not protect users that have enabled
347 the "auto-detect character encoding" feature on their browser.</p>
351 <li><code class="directive"><a href="../mod/mod_mime.html#addcharset">AddCharset</a></code></li>
354 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
355 <div class="directive-section"><h2><a name="AllowEncodedSlashes" id="AllowEncodedSlashes">AllowEncodedSlashes</a> <a name="allowencodedslashes" id="allowencodedslashes">Directive</a></h2>
356 <table class="directive">
357 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines whether encoded path separators in URLs are allowed to
358 be passed through</td></tr>
359 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AllowEncodedSlashes On|Off|NoDecode</code></td></tr>
360 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AllowEncodedSlashes Off</code></td></tr>
361 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
362 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
363 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
364 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache httpd 2.0.46 and later.
365 NoDecode option available in 2.3.12 and later.</td></tr>
367 <p>The <code class="directive">AllowEncodedSlashes</code> directive allows URLs
368 which contain encoded path separators (<code>%2F</code> for <code>/</code>
369 and additionally <code>%5C</code> for <code>\</code> on according systems)
370 to be used in the path info.</p>
372 <p>With the default value, <code>Off</code>, such URLs are refused
373 with a 404 (Not found) error.</p>
375 <p>With the value <code>On</code>, such URLs are accepted, and encoded
376 slashes are decoded like all other encoded characters.</p>
378 <p>With the value <code>NoDecode</code>, such URLs are accepted, but
379 encoded slashes are not decoded but left in their encoded state.</p>
381 <p>Turning <code class="directive">AllowEncodedSlashes</code> <code>On</code> is
382 mostly useful when used in conjunction with <code>PATH_INFO</code>.</p>
384 <div class="note"><h3>Note</h3>
385 <p>If encoded slashes are needed in path info, use of <code>NoDecode</code> is
386 strongly recommended as a security measure. Allowing slashes
387 to be decoded could potentially allow unsafe paths.</p>
392 <li><code class="directive"><a href="#acceptpathinfo">AcceptPathInfo</a></code></li>
395 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
396 <div class="directive-section"><h2><a name="AllowOverride" id="AllowOverride">AllowOverride</a> <a name="allowoverride" id="allowoverride">Directive</a></h2>
397 <table class="directive">
398 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Types of directives that are allowed in
399 <code>.htaccess</code> files</td></tr>
400 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AllowOverride All|None|<var>directive-type</var>
401 [<var>directive-type</var>] ...</code></td></tr>
402 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AllowOverride None (2.3.9 and later), AllowOverride All (2.3.8 and earlier)</code></td></tr>
403 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory</td></tr>
404 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
405 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
407 <p>When the server finds an <code>.htaccess</code> file (as
408 specified by <code class="directive"><a href="#accessfilename">AccessFileName</a></code>)
409 it needs to know which directives declared in that file can override
410 earlier configuration directives.</p>
412 <div class="note"><h3>Only available in <Directory> sections</h3>
413 <code class="directive">AllowOverride</code> is valid only in
414 <code class="directive"><a href="#directory"><Directory></a></code>
415 sections specified without regular expressions, not in <code class="directive"><a href="#location"><Location></a></code>, <code class="directive"><a href="#directorymatch"><DirectoryMatch></a></code> or
416 <code class="directive"><a href="#files"><Files></a></code> sections.
419 <p>When this directive is set to <code>None</code>, then
420 <a href="#accessfilename">.htaccess</a> files are completely ignored.
421 In this case, the server will not even attempt to read
422 <code>.htaccess</code> files in the filesystem.</p>
424 <p>When this directive is set to <code>All</code>, then any
425 directive which has the .htaccess <a href="directive-dict.html#Context">Context</a> is allowed in
426 <code>.htaccess</code> files.</p>
428 <p>The <var>directive-type</var> can be one of the following
429 groupings of directives.</p>
436 Allow use of the authorization directives (<code class="directive"><a href="../mod/mod_authn_dbm.html#authdbmgroupfile">AuthDBMGroupFile</a></code>,
437 <code class="directive"><a href="../mod/mod_authn_dbm.html#authdbmuserfile">AuthDBMUserFile</a></code>,
438 <code class="directive"><a href="../mod/mod_authz_groupfile.html#authgroupfile">AuthGroupFile</a></code>,
439 <code class="directive"><a href="../mod/mod_authn_core.html#authname">AuthName</a></code>,
440 <code class="directive"><a href="../mod/mod_authn_core.html#authtype">AuthType</a></code>, <code class="directive"><a href="../mod/mod_authn_file.html#authuserfile">AuthUserFile</a></code>, <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code>, <em>etc.</em>).</dd>
445 Allow use of the directives controlling document types
446 (<code class="directive"><a href="#errordocument">ErrorDocument</a></code>,
447 <code class="directive"><a href="#forcetype">ForceType</a></code>,
448 <code class="directive"><a href="../mod/mod_negotiation.html#languagepriority">LanguagePriority</a></code>,
449 <code class="directive"><a href="#sethandler">SetHandler</a></code>,
450 <code class="directive"><a href="#setinputfilter">SetInputFilter</a></code>,
451 <code class="directive"><a href="#setoutputfilter">SetOutputFilter</a></code>, and
452 <code class="module"><a href="../mod/mod_mime.html">mod_mime</a></code> Add* and Remove* directives),
453 document meta data (<code class="directive"><a href="../mod/mod_headers.html#header">Header</a></code>, <code class="directive"><a href="../mod/mod_headers.html#requestheader">RequestHeader</a></code>, <code class="directive"><a href="../mod/mod_setenvif.html#setenvif">SetEnvIf</a></code>, <code class="directive"><a href="../mod/mod_setenvif.html#setenvifnocase">SetEnvIfNoCase</a></code>, <code class="directive"><a href="../mod/mod_setenvif.html#browsermatch">BrowserMatch</a></code>, <code class="directive"><a href="../mod/mod_usertrack.html#cookieexpires">CookieExpires</a></code>, <code class="directive"><a href="../mod/mod_usertrack.html#cookiedomain">CookieDomain</a></code>, <code class="directive"><a href="../mod/mod_usertrack.html#cookiestyle">CookieStyle</a></code>, <code class="directive"><a href="../mod/mod_usertrack.html#cookietracking">CookieTracking</a></code>, <code class="directive"><a href="../mod/mod_usertrack.html#cookiename">CookieName</a></code>),
454 <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> directives <code class="directive"><a href="../mod/mod_rewrite.html#rewriteengine">RewriteEngine</a></code>, <code class="directive"><a href="../mod/mod_rewrite.html#rewriteoptions">RewriteOptions</a></code>, <code class="directive"><a href="../mod/mod_rewrite.html#rewritebase">RewriteBase</a></code>, <code class="directive"><a href="../mod/mod_rewrite.html#rewritecond">RewriteCond</a></code>, <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code>) and
455 <code class="directive"><a href="../mod/mod_actions.html#action">Action</a></code> from
456 <code class="module"><a href="../mod/mod_actions.html">mod_actions</a></code>.
462 Allow use of the directives controlling directory indexing
463 (<code class="directive"><a href="../mod/mod_autoindex.html#adddescription">AddDescription</a></code>,
464 <code class="directive"><a href="../mod/mod_autoindex.html#addicon">AddIcon</a></code>, <code class="directive"><a href="../mod/mod_autoindex.html#addiconbyencoding">AddIconByEncoding</a></code>,
465 <code class="directive"><a href="../mod/mod_autoindex.html#addiconbytype">AddIconByType</a></code>,
466 <code class="directive"><a href="../mod/mod_autoindex.html#defaulticon">DefaultIcon</a></code>, <code class="directive"><a href="../mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>, <code class="directive"><a href="../mod/mod_autoindex.html#fancyindexing">FancyIndexing</a></code>, <code class="directive"><a href="../mod/mod_autoindex.html#headername">HeaderName</a></code>, <code class="directive"><a href="../mod/mod_autoindex.html#indexignore">IndexIgnore</a></code>, <code class="directive"><a href="../mod/mod_autoindex.html#indexoptions">IndexOptions</a></code>, <code class="directive"><a href="../mod/mod_autoindex.html#readmename">ReadmeName</a></code>,
472 Allow use of the directives controlling host access (<code class="directive"><a href="../mod/mod_authz_host.html#allow">Allow</a></code>, <code class="directive"><a href="../mod/mod_authz_host.html#deny">Deny</a></code> and <code class="directive"><a href="../mod/mod_authz_host.html#order">Order</a></code>).</dd>
474 <dt>Options[=<var>Option</var>,...]</dt>
477 Allow use of the directives controlling specific directory
478 features (<code class="directive"><a href="#options">Options</a></code> and
479 <code class="directive"><a href="../mod/mod_include.html#xbithack">XBitHack</a></code>).
480 An equal sign may be given followed by a comma (but no spaces)
481 separated lists of options that may be set using the <code class="directive"><a href="#options">Options</a></code> command.</dd>
486 <div class="example"><p><code>
487 AllowOverride AuthConfig Indexes
490 <p>In the example above all directives that are neither in the group
491 <code>AuthConfig</code> nor <code>Indexes</code> cause an internal
494 <div class="note"><p>For security and performance reasons, do not set
495 <code>AllowOverride</code> to anything other than <code>None</code>
496 in your <code><Directory /></code> block. Instead, find (or
497 create) the <code><Directory></code> block that refers to the
498 directory where you're actually planning to place a
499 <code>.htaccess</code> file.</p>
504 <li><code class="directive"><a href="#accessfilename">AccessFileName</a></code></li>
505 <li><a href="../configuring.html">Configuration Files</a></li>
506 <li><a href="../howto/htaccess.html">.htaccess Files</a></li>
509 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
510 <div class="directive-section"><h2><a name="CGIMapExtension" id="CGIMapExtension">CGIMapExtension</a> <a name="cgimapextension" id="cgimapextension">Directive</a></h2>
511 <table class="directive">
512 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Technique for locating the interpreter for CGI
514 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CGIMapExtension <var>cgi-path</var> <var>.extension</var></code></td></tr>
515 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
516 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
517 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
518 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
519 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>NetWare only</td></tr>
521 <p>This directive is used to control how Apache httpd finds the
522 interpreter used to run CGI scripts. For example, setting
523 <code>CGIMapExtension sys:\foo.nlm .foo</code> will
524 cause all CGI script files with a <code>.foo</code> extension to
525 be passed to the FOO interpreter.</p>
528 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
529 <div class="directive-section"><h2><a name="ContentDigest" id="ContentDigest">ContentDigest</a> <a name="contentdigest" id="contentdigest">Directive</a></h2>
530 <table class="directive">
531 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables the generation of <code>Content-MD5</code> HTTP Response
533 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ContentDigest On|Off</code></td></tr>
534 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ContentDigest Off</code></td></tr>
535 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
536 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Options</td></tr>
537 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
538 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
540 <p>This directive enables the generation of
541 <code>Content-MD5</code> headers as defined in RFC1864
542 respectively RFC2616.</p>
544 <p>MD5 is an algorithm for computing a "message digest"
545 (sometimes called "fingerprint") of arbitrary-length data, with
546 a high degree of confidence that any alterations in the data
547 will be reflected in alterations in the message digest.</p>
549 <p>The <code>Content-MD5</code> header provides an end-to-end
550 message integrity check (MIC) of the entity-body. A proxy or
551 client may check this header for detecting accidental
552 modification of the entity-body in transit. Example header:</p>
554 <div class="example"><p><code>
555 Content-MD5: AuLb7Dp1rqtRtxz2m9kRpA==
558 <p>Note that this can cause performance problems on your server
559 since the message digest is computed on every request (the
560 values are not cached).</p>
562 <p><code>Content-MD5</code> is only sent for documents served
563 by the <code class="module"><a href="../mod/core.html">core</a></code>, and not by any module. For example,
564 SSI documents, output from CGI scripts, and byte range responses
565 do not have this header.</p>
568 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
569 <div class="directive-section"><h2><a name="DefaultType" id="DefaultType">DefaultType</a> <a name="defaulttype" id="defaulttype">Directive</a></h2>
570 <table class="directive">
571 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>This directive has no effect other than to emit warnings
572 if the value is not <code>none</code>. In prior versions, DefaultType
573 would specify a default media type to assign to response content for
574 which no other media type configuration could be found.
576 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DefaultType <var>media-type|none</var></code></td></tr>
577 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DefaultType none</code></td></tr>
578 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
579 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
580 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
581 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
582 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>The argument <code>none</code> is available in Apache httpd 2.2.7 and later. All other choices are DISABLED for 2.3.x and later.</td></tr>
584 <p>This directive has been disabled. For backwards compatibility
585 of configuration files, it may be specified with the value
586 <code>none</code>, meaning no default media type. For example:</p>
588 <div class="example"><p><code>
592 <p><code>DefaultType None</code> is only available in
593 httpd-2.2.7 and later.</p>
595 <p>Use the mime.types configuration file and the
596 <code class="directive"><a href="../mod/mod_mime.html#addtype">AddType</a></code> to configure media
597 type assignments via file extensions, or the
598 <code class="directive"><a href="#forcetype">ForceType</a></code> directive to configure
599 the media type for specific resources. Otherwise, the server will
600 send the response without a Content-Type header field and the
601 recipient may attempt to guess the media type.</p>
604 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
605 <div class="directive-section"><h2><a name="Define" id="Define">Define</a> <a name="define" id="define">Directive</a></h2>
606 <table class="directive">
607 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Define a variable</td></tr>
608 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Define <var>parameter-name</var> [<var>parameter-value</var>]</code></td></tr>
609 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
610 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
611 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
613 <p>In its one parameter form, <code class="directive">Define</code> is equivalent
614 to passing the <code>-D</code> argument to <code class="program"><a href="../programs/httpd.html">httpd</a></code>. It
615 can be used to toggle the use of
616 <code class="directive"><a href="#ifdefine"><IfDefine></a></code> sections
617 without needing to alter <code>-D</code> arguments in any startup
620 <p>In addition to that, if the second parameter is given, a config variable
621 is set to this value. The variable can be used in the configuration using
622 the <code>${VAR}</code> syntax. The variable is always globally defined
623 and not limited to the scope of the surrounding config section.</p>
625 <div class="example"><p><code>
626 <IfDefine TEST><br />
627 Define servername test.example.com<br />
628 </IfDefine><br />
629 <IfDefine !TEST><br />
630 Define servername www.example.com<br />
631 Define SSL<br />
632 </IfDefine><br />
635 <p>Variable names may not contain colon ":" characters, to avoid clashes
636 with <code class="directive"><a href="../mod/mod_rewrite.html#rewritemap">RewriteMap</a></code>'s syntax.</p>
639 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
640 <div class="directive-section"><h2><a name="Directory" id="Directory"><Directory></a> <a name="directory" id="directory">Directive</a></h2>
641 <table class="directive">
642 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enclose a group of directives that apply only to the
643 named file-system directory, sub-directories, and their contents.</td></tr>
644 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Directory <var>directory-path</var>>
645 ... </Directory></code></td></tr>
646 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
647 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
648 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
650 <p><code class="directive"><Directory></code> and
651 <code></Directory></code> are used to enclose a group of
652 directives that will apply only to the named directory,
653 sub-directories of that directory, and the files within the respective
654 directories. Any directive that is allowed
655 in a directory context may be used. <var>Directory-path</var> is
656 either the full path to a directory, or a wild-card string using
657 Unix shell-style matching. In a wild-card string, <code>?</code> matches
658 any single character, and <code>*</code> matches any sequences of
659 characters. You may also use <code>[]</code> character ranges. None
660 of the wildcards match a `/' character, so <code><Directory
661 /*/public_html></code> will not match
662 <code>/home/user/public_html</code>, but <code><Directory
663 /home/*/public_html></code> will match. Example:</p>
665 <div class="example"><p><code>
666 <Directory /usr/local/httpd/htdocs><br />
667 <span class="indent">
668 Options Indexes FollowSymLinks<br />
674 <p>Be careful with the <var>directory-path</var> arguments:
675 They have to literally match the filesystem path which Apache httpd uses
676 to access the files. Directives applied to a particular
677 <code><Directory></code> will not apply to files accessed from
678 that same directory via a different path, such as via different symbolic
682 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular
683 expressions</a> can also be used, with the addition of the
684 <code>~</code> character. For example:</p>
686 <div class="example"><p><code>
687 <Directory ~ "^/www/.*/[0-9]{3}">
690 <p>would match directories in <code>/www/</code> that consisted of
693 <p>If multiple (non-regular expression) <code class="directive"><Directory></code> sections
694 match the directory (or one of its parents) containing a document,
695 then the directives are applied in the order of shortest match
696 first, interspersed with the directives from the <a href="#accessfilename">.htaccess</a> files. For example,
699 <div class="example"><p><code>
700 <Directory /><br />
701 <span class="indent">
702 AllowOverride None<br />
704 </Directory><br />
706 <Directory /home><br />
707 <span class="indent">
708 AllowOverride FileInfo<br />
713 <p>for access to the document <code>/home/web/dir/doc.html</code>
717 <li>Apply directive <code>AllowOverride None</code>
718 (disabling <code>.htaccess</code> files).</li>
720 <li>Apply directive <code>AllowOverride FileInfo</code> (for
721 directory <code>/home</code>).</li>
723 <li>Apply any <code>FileInfo</code> directives in
724 <code>/home/.htaccess</code>, <code>/home/web/.htaccess</code> and
725 <code>/home/web/dir/.htaccess</code> in that order.</li>
728 <p>Regular expressions are not considered until after all of the
729 normal sections have been applied. Then all of the regular
730 expressions are tested in the order they appeared in the
731 configuration file. For example, with</p>
733 <div class="example"><p><code>
734 <Directory ~ abc$><br />
735 <span class="indent">
736 # ... directives here ...<br />
741 <p>the regular expression section won't be considered until after
742 all normal <code class="directive"><Directory></code>s and
743 <code>.htaccess</code> files have been applied. Then the regular
744 expression will match on <code>/home/abc/public_html/abc</code> and
745 the corresponding <code class="directive"><Directory></code> will
748 <p><strong>Note that the default access for
749 <code><Directory /></code> is to permit all access.
750 This means that Apache httpd will serve any file mapped from an URL. It is
751 recommended that you change this with a block such
754 <div class="example"><p><code>
755 <Directory /><br />
756 <span class="indent">
757 Require all denied<br />
762 <p><strong>and then override this for directories you
763 <em>want</em> accessible. See the <a href="../misc/security_tips.html">Security Tips</a> page for more
764 details.</strong></p>
766 <p>The directory sections occur in the <code>httpd.conf</code> file.
767 <code class="directive"><Directory></code> directives
768 cannot nest, and cannot appear in a <code class="directive"><a href="#limit"><Limit></a></code> or <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> section.</p>
772 <li><a href="../sections.html">How <Directory>,
773 <Location> and <Files> sections work</a> for an
774 explanation of how these different sections are combined when a
775 request is received</li>
778 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
779 <div class="directive-section"><h2><a name="DirectoryMatch" id="DirectoryMatch"><DirectoryMatch></a> <a name="directorymatch" id="directorymatch">Directive</a></h2>
780 <table class="directive">
781 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enclose directives that apply to
782 the contents of file-system directories matching a regular expression.</td></tr>
783 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><DirectoryMatch <var>regex</var>>
784 ... </DirectoryMatch></code></td></tr>
785 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
786 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
787 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
789 <p><code class="directive"><DirectoryMatch></code> and
790 <code></DirectoryMatch></code> are used to enclose a group
791 of directives which will apply only to the named directory (and the files within),
792 the same as <code class="directive"><a href="#directory"><Directory></a></code>.
793 However, it takes as an argument a
794 <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expression</a>. For example:</p>
796 <div class="example"><p><code>
797 <DirectoryMatch "^/www/(.+/)?[0-9]{3}">
800 <p>would match directories in <code>/www/</code> that consisted of three
803 <div class="note"><h3>Compatability</h3>
804 Prior to 2.3.9, this directive implicitly applied to sub-directories
805 (like <code class="directive"><a href="#directory"><Directory></a></code>) and
806 could not match the end of line symbol ($). In 2.3.9 and later,
807 only directories that match the expression are affected by the enclosed
811 <div class="note"><h3>Trailing Slash</h3>
812 This directive applies to requests for directories that may or may
813 not end in a trailing slash, so expressions that are anchored to the
814 end of line ($) must be written with care.
819 <li><code class="directive"><a href="#directory"><Directory></a></code> for
820 a description of how regular expressions are mixed in with normal
821 <code class="directive"><Directory></code>s</li>
822 <li><a href="../sections.html">How <Directory>, <Location> and
823 <Files> sections work</a> for an explanation of how these different
824 sections are combined when a request is received</li>
827 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
828 <div class="directive-section"><h2><a name="DocumentRoot" id="DocumentRoot">DocumentRoot</a> <a name="documentroot" id="documentroot">Directive</a></h2>
829 <table class="directive">
830 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Directory that forms the main document tree visible
831 from the web</td></tr>
832 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DocumentRoot <var>directory-path</var></code></td></tr>
833 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DocumentRoot /usr/local/apache/htdocs</code></td></tr>
834 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
835 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
836 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
838 <p>This directive sets the directory from which <code class="program"><a href="../programs/httpd.html">httpd</a></code>
839 will serve files. Unless matched by a directive like <code class="directive"><a href="../mod/mod_alias.html#alias">Alias</a></code>, the server appends the
840 path from the requested URL to the document root to make the
841 path to the document. Example:</p>
843 <div class="example"><p><code>
844 DocumentRoot /usr/web
848 <code>http://my.example.com/index.html</code> refers to
849 <code>/usr/web/index.html</code>. If the <var>directory-path</var> is
850 not absolute then it is assumed to be relative to the <code class="directive"><a href="#serverroot">ServerRoot</a></code>.</p>
852 <p>The <code class="directive">DocumentRoot</code> should be specified without
853 a trailing slash.</p>
857 <li><a href="../urlmapping.html#documentroot">Mapping URLs to Filesystem
861 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
862 <div class="directive-section"><h2><a name="Else" id="Else"><Else></a> <a name="else" id="else">Directive</a></h2>
863 <table class="directive">
864 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if the condition of a
865 previous <code class="directive"><a href="#if"><If></a></code> or
866 <code class="directive"><a href="#elseif"><ElseIf></a></code> section is not
867 satisfied by a request at runtime</td></tr>
868 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Else> ... </Else></code></td></tr>
869 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
870 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
871 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
872 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
874 <p>The <code class="directive"><Else></code> applies the enclosed
875 directives if and only if the most recent
876 <code class="directive"><If></code> or
877 <code class="directive"><ElseIf></code> section
878 in the same scope has not been applied.
881 <div class="example"><p><code>
882 <If "-z req('Host')"><br />
890 <p> The <code class="directive"><If></code> would match HTTP/1.0
891 requests without a <var>Host:</var> header and the
892 <code class="directive"><Else></code> would match requests
893 with a <var>Host:</var> header.</p>
898 <li><code class="directive"><a href="#if"><If></a></code></li>
899 <li><code class="directive"><a href="#elseif"><ElseIf></a></code></li>
900 <li><a href="../sections.html">How <Directory>, <Location>,
901 <Files> sections work</a> for an explanation of how these
902 different sections are combined when a request is received.
903 <code class="directive"><If></code>,
904 <code class="directive"><ElseIf></code>, and
905 <code class="directive"><Else></code> are applied last.</li>
908 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
909 <div class="directive-section"><h2><a name="ElseIf" id="ElseIf"><ElseIf></a> <a name="elseif" id="elseif">Directive</a></h2>
910 <table class="directive">
911 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if a condition is satisfied
912 by a request at runtime while the condition of a previous
913 <code class="directive"><a href="#if"><If></a></code> or
914 <code class="directive"><ElseIf></code> section is not
916 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><ElseIf <var>expression</var>> ... </ElseIf></code></td></tr>
917 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
918 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
919 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
920 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
922 <p>The <code class="directive"><ElseIf></code> applies the enclosed
923 directives if and only if both the given condition evaluates to true and
924 the most recent <code class="directive"><If></code> or
925 <code class="directive"><ElseIf></code> section in the same scope has
926 not been applied. For example: In </p>
928 <div class="example"><p><code>
929 <If "-R '10.1.0.0/16'"><br />
932 <ElseIf "-R '10.0.0.0/8'"><br />
934 </ElseIf><br />
940 <p>The <code class="directive"><ElseIf></code> would match if
941 the remote address of a request belongs to the subnet 10.0.0.0/8 but
942 not to the subnet 10.1.0.0/16.</p>
947 <li><a href="../expr.html">Expressions in Apache HTTP Server</a>,
948 for a complete reference and more examples.</li>
949 <li><code class="directive"><a href="#if"><If></a></code></li>
950 <li><code class="directive"><a href="#else"><Else></a></code></li>
951 <li><a href="../sections.html">How <Directory>, <Location>,
952 <Files> sections work</a> for an explanation of how these
953 different sections are combined when a request is received.
954 <code class="directive"><If></code>,
955 <code class="directive"><ElseIf></code>, and
956 <code class="directive"><Else></code> are applied last.</li>
959 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
960 <div class="directive-section"><h2><a name="EnableMMAP" id="EnableMMAP">EnableMMAP</a> <a name="enablemmap" id="enablemmap">Directive</a></h2>
961 <table class="directive">
962 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Use memory-mapping to read files during delivery</td></tr>
963 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>EnableMMAP On|Off</code></td></tr>
964 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>EnableMMAP On</code></td></tr>
965 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
966 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
967 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
968 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
970 <p>This directive controls whether the <code class="program"><a href="../programs/httpd.html">httpd</a></code> may use
971 memory-mapping if it needs to read the contents of a file during
972 delivery. By default, when the handling of a request requires
973 access to the data within a file -- for example, when delivering a
974 server-parsed file using <code class="module"><a href="../mod/mod_include.html">mod_include</a></code> -- Apache httpd
975 memory-maps the file if the OS supports it.</p>
977 <p>This memory-mapping sometimes yields a performance improvement.
978 But in some environments, it is better to disable the memory-mapping
979 to prevent operational problems:</p>
982 <li>On some multiprocessor systems, memory-mapping can reduce the
983 performance of the <code class="program"><a href="../programs/httpd.html">httpd</a></code>.</li>
984 <li>Deleting or truncating a file while <code class="program"><a href="../programs/httpd.html">httpd</a></code>
985 has it memory-mapped can cause <code class="program"><a href="../programs/httpd.html">httpd</a></code> to
986 crash with a segmentation fault.
990 <p>For server configurations that are vulnerable to these problems,
991 you should disable memory-mapping of delivered files by specifying:</p>
993 <div class="example"><p><code>
997 <p>For NFS mounted files, this feature may be disabled explicitly for
998 the offending files by specifying:</p>
1000 <div class="example"><p><code>
1001 <Directory "/path-to-nfs-files">
1002 <span class="indent">
1009 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1010 <div class="directive-section"><h2><a name="EnableSendfile" id="EnableSendfile">EnableSendfile</a> <a name="enablesendfile" id="enablesendfile">Directive</a></h2>
1011 <table class="directive">
1012 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Use the kernel sendfile support to deliver files to the client</td></tr>
1013 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>EnableSendfile On|Off</code></td></tr>
1014 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>EnableSendfile Off</code></td></tr>
1015 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1016 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1017 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1018 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1019 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.0.44 and later. Default changed to Off in
1020 version 2.3.9.</td></tr>
1022 <p>This directive controls whether <code class="program"><a href="../programs/httpd.html">httpd</a></code> may use the
1023 sendfile support from the kernel to transmit file contents to the client.
1024 By default, when the handling of a request requires no access
1025 to the data within a file -- for example, when delivering a
1026 static file -- Apache httpd uses sendfile to deliver the file contents
1027 without ever reading the file if the OS supports it.</p>
1029 <p>This sendfile mechanism avoids separate read and send operations,
1030 and buffer allocations. But on some platforms or within some
1031 filesystems, it is better to disable this feature to avoid
1032 operational problems:</p>
1035 <li>Some platforms may have broken sendfile support that the build
1036 system did not detect, especially if the binaries were built on
1037 another box and moved to such a machine with broken sendfile
1039 <li>On Linux the use of sendfile triggers TCP-checksum
1040 offloading bugs on certain networking cards when using IPv6.</li>
1041 <li>On Linux on Itanium, <code>sendfile</code> may be unable to handle
1042 files over 2GB in size.</li>
1043 <li>With a network-mounted <code class="directive"><a href="#documentroot">DocumentRoot</a></code> (e.g., NFS, SMB, CIFS, FUSE),
1044 the kernel may be unable to serve the network file through
1048 <p>For server configurations that are not vulnerable to these problems,
1049 you may enable this feature by specifying:</p>
1051 <div class="example"><p><code>
1055 <p>For network mounted files, this feature may be disabled explicitly
1056 for the offending files by specifying:</p>
1058 <div class="example"><p><code>
1059 <Directory "/path-to-nfs-files">
1060 <span class="indent">
1065 <p>Please note that the per-directory and .htaccess configuration
1066 of <code class="directive">EnableSendfile</code> is not supported by
1067 <code class="module"><a href="../mod/mod_cache_disk.html">mod_cache_disk</a></code>.
1068 Only global definition of <code class="directive">EnableSendfile</code>
1069 is taken into account by the module.
1073 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1074 <div class="directive-section"><h2><a name="Error" id="Error">Error</a> <a name="error" id="error">Directive</a></h2>
1075 <table class="directive">
1076 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Abort configuration parsing with a custom error message</td></tr>
1077 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Error <var>message</var></code></td></tr>
1078 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1079 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1080 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1081 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.3.9 and later</td></tr>
1083 <p>If an error can be detected within the configuration, this
1084 directive can be used to generate a custom error message, and halt
1085 configuration parsing. The typical use is for reporting required
1086 modules which are missing from the configuration.</p>
1088 <div class="example"><h3>Example</h3><p><code>
1089 # ensure that mod_include is loaded<br />
1090 <IfModule !include_module><br />
1091 Error mod_include is required by mod_foo. Load it with LoadModule.<br />
1092 </IfModule><br />
1094 # ensure that exactly one of SSL,NOSSL is defined<br />
1095 <IfDefine SSL><br />
1096 <IfDefine NOSSL><br />
1097 Error Both SSL and NOSSL are defined. Define only one of them.<br />
1098 </IfDefine><br />
1099 </IfDefine><br />
1100 <IfDefine !SSL><br />
1101 <IfDefine !NOSSL><br />
1102 Error Either SSL or NOSSL must be defined.<br />
1103 </IfDefine><br />
1104 </IfDefine><br />
1109 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1110 <div class="directive-section"><h2><a name="ErrorDocument" id="ErrorDocument">ErrorDocument</a> <a name="errordocument" id="errordocument">Directive</a></h2>
1111 <table class="directive">
1112 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>What the server will return to the client
1113 in case of an error</td></tr>
1114 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ErrorDocument <var>error-code</var> <var>document</var></code></td></tr>
1115 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1116 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1117 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1118 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1120 <p>In the event of a problem or error, Apache httpd can be configured
1121 to do one of four things,</p>
1124 <li>output a simple hardcoded error message</li>
1126 <li>output a customized message</li>
1128 <li>redirect to a local <var>URL-path</var> to handle the
1131 <li>redirect to an external <var>URL</var> to handle the
1135 <p>The first option is the default, while options 2-4 are
1136 configured using the <code class="directive">ErrorDocument</code>
1137 directive, which is followed by the HTTP response code and a URL
1138 or a message. Apache httpd will sometimes offer additional information
1139 regarding the problem/error.</p>
1141 <p>URLs can begin with a slash (/) for local web-paths (relative
1142 to the <code class="directive"><a href="#documentroot">DocumentRoot</a></code>), or be a
1143 full URL which the client can resolve. Alternatively, a message
1144 can be provided to be displayed by the browser. Examples:</p>
1146 <div class="example"><p><code>
1147 ErrorDocument 500 http://foo.example.com/cgi-bin/tester<br />
1148 ErrorDocument 404 /cgi-bin/bad_urls.pl<br />
1149 ErrorDocument 401 /subscription_info.html<br />
1150 ErrorDocument 403 "Sorry can't allow you access today"
1153 <p>Additionally, the special value <code>default</code> can be used
1154 to specify Apache httpd's simple hardcoded message. While not required
1155 under normal circumstances, <code>default</code> will restore
1156 Apache httpd's simple hardcoded message for configurations that would
1157 otherwise inherit an existing <code class="directive">ErrorDocument</code>.</p>
1159 <div class="example"><p><code>
1160 ErrorDocument 404 /cgi-bin/bad_urls.pl<br /><br />
1161 <Directory /web/docs><br />
1162 <span class="indent">
1163 ErrorDocument 404 default<br />
1168 <p>Note that when you specify an <code class="directive">ErrorDocument</code>
1169 that points to a remote URL (ie. anything with a method such as
1170 <code>http</code> in front of it), Apache HTTP Server will send a redirect to the
1171 client to tell it where to find the document, even if the
1172 document ends up being on the same server. This has several
1173 implications, the most important being that the client will not
1174 receive the original error status code, but instead will
1175 receive a redirect status code. This in turn can confuse web
1176 robots and other clients which try to determine if a URL is
1177 valid using the status code. In addition, if you use a remote
1178 URL in an <code>ErrorDocument 401</code>, the client will not
1179 know to prompt the user for a password since it will not
1180 receive the 401 status code. Therefore, <strong>if you use an
1181 <code>ErrorDocument 401</code> directive then it must refer to a local
1182 document.</strong></p>
1184 <p>Microsoft Internet Explorer (MSIE) will by default ignore
1185 server-generated error messages when they are "too small" and substitute
1186 its own "friendly" error messages. The size threshold varies depending on
1187 the type of error, but in general, if you make your error document
1188 greater than 512 bytes, then MSIE will show the server-generated
1189 error rather than masking it. More information is available in
1190 Microsoft Knowledge Base article <a href="http://support.microsoft.com/default.aspx?scid=kb;en-us;Q294807">Q294807</a>.</p>
1192 <p>Although most error messages can be overriden, there are certain
1193 circumstances where the internal messages are used regardless of the
1194 setting of <code class="directive"><a href="#errordocument">ErrorDocument</a></code>. In
1195 particular, if a malformed request is detected, normal request processing
1196 will be immediately halted and the internal error message returned.
1197 This is necessary to guard against security problems caused by
1200 <p>If you are using mod_proxy, you may wish to enable
1201 <code class="directive"><a href="../mod/mod_proxy.html#proxyerroroverride">ProxyErrorOverride</a></code> so that you can provide
1202 custom error messages on behalf of your Origin servers. If you don't enable ProxyErrorOverride,
1203 Apache httpd will not generate custom error documents for proxied content.</p>
1207 <li><a href="../custom-error.html">documentation of
1208 customizable responses</a></li>
1211 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1212 <div class="directive-section"><h2><a name="ErrorLog" id="ErrorLog">ErrorLog</a> <a name="errorlog" id="errorlog">Directive</a></h2>
1213 <table class="directive">
1214 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Location where the server will log errors</td></tr>
1215 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code> ErrorLog <var>file-path</var>|syslog[:<var>facility</var>]</code></td></tr>
1216 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ErrorLog logs/error_log (Unix) ErrorLog logs/error.log (Windows and OS/2)</code></td></tr>
1217 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1218 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1219 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1221 <p>The <code class="directive">ErrorLog</code> directive sets the name of
1222 the file to which the server will log any errors it encounters. If
1223 the <var>file-path</var> is not absolute then it is assumed to be
1224 relative to the <code class="directive"><a href="#serverroot">ServerRoot</a></code>.</p>
1226 <div class="example"><h3>Example</h3><p><code>
1227 ErrorLog /var/log/httpd/error_log
1230 <p>If the <var>file-path</var>
1231 begins with a pipe character "<code>|</code>" then it is assumed to be a
1232 command to spawn to handle the error log.</p>
1234 <div class="example"><h3>Example</h3><p><code>
1235 ErrorLog "|/usr/local/bin/httpd_errors"
1238 <p>See the notes on <a href="../logs.html#piped">piped logs</a> for
1239 more information.</p>
1241 <p>Using <code>syslog</code> instead of a filename enables logging
1242 via syslogd(8) if the system supports it. The default is to use
1243 syslog facility <code>local7</code>, but you can override this by
1244 using the <code>syslog:<var>facility</var></code> syntax where
1245 <var>facility</var> can be one of the names usually documented in
1246 syslog(1). The facility is effectively global, and if it is changed
1247 in individual virtual hosts, the final facility specified affects the
1250 <div class="example"><h3>Example</h3><p><code>
1251 ErrorLog syslog:user
1254 <p>SECURITY: See the <a href="../misc/security_tips.html#serverroot">security tips</a>
1255 document for details on why your security could be compromised
1256 if the directory where log files are stored is writable by
1257 anyone other than the user that starts the server.</p>
1258 <div class="warning"><h3>Note</h3>
1259 <p>When entering a file path on non-Unix platforms, care should be taken
1260 to make sure that only forward slashes are used even though the platform
1261 may allow the use of back slashes. In general it is a good idea to always
1262 use forward slashes throughout the configuration files.</p>
1267 <li><code class="directive"><a href="#loglevel">LogLevel</a></code></li>
1268 <li><a href="../logs.html">Apache HTTP Server Log Files</a></li>
1271 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1272 <div class="directive-section"><h2><a name="ErrorLogFormat" id="ErrorLogFormat">ErrorLogFormat</a> <a name="errorlogformat" id="errorlogformat">Directive</a></h2>
1273 <table class="directive">
1274 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Format specification for error log entries</td></tr>
1275 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code> ErrorLog [connection|request] <var>format</var></code></td></tr>
1276 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1277 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1278 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1279 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache httpd 2.3.9 and later</td></tr>
1281 <p><code class="directive">ErrorLogFormat</code> allows to specify what
1282 supplementary information is logged in the error log in addition to the
1283 actual log message.</p>
1285 <div class="example"><h3>Simple example</h3><p><code>
1286 ErrorLogFormat "[%t] [%l] [pid %P] %F: %E: [client %a] %M"
1289 <p>Specifying <code>connection</code> or <code>request</code> as first
1290 parameter allows to specify additional formats, causing additional
1291 information to be logged when the first message is logged for a specific
1292 connection or request, respectivly. This additional information is only
1293 logged once per connection/request. If a connection or request is processed
1294 without causing any log message, the additional information is not logged
1297 <p>It can happen that some format string items do not produce output. For
1298 example, the Referer header is only present if the log message is
1299 associated to a request and the log message happens at a time when the
1300 Referer header has already been read from the client. If no output is
1301 produced, the default behaviour is to delete everything from the preceeding
1302 space character to the next space character. This means the log line is
1303 implicitly divided into fields on non-whitespace to whitespace transitions.
1304 If a format string item does not produce output, the whole field is
1305 ommitted. For example, if the remote address <code>%a</code> in the log
1306 format <code>[%t] [%l] [%a] %M </code> is not available, the surrounding
1307 brackets are not logged either. Space characters can be escaped with a
1308 backslash to prevent them from delimiting a field. The combination '% '
1309 (percent space) is a zero-witdh field delimiter that does not produce any
1312 <p>The above behaviour can be changed by adding modifiers to the format
1313 string item. A <code>-</code> (minus) modifier causes a minus to be logged if the
1314 respective item does not produce any output. In once-per-connection/request
1315 formats, it is also possible to use the <code>+</code> (plus) modifier. If an
1316 item with the plus modifier does not produce any output, the whole line is
1319 <p>A number as modifier can be used to assign a log severity level to a
1320 format item. The item will only be logged if the severity of the log
1321 message is not higher than the specified log severity level. The number can
1322 range from 1 (alert) over 4 (warn) and 7 (debug) to 15 (trace8).</p>
1324 <p>Some format string items accept additional parameters in braces.</p>
1326 <table class="bordered"><tr class="header"><th>Format String</th> <th>Description</th></tr>
1327 <tr><td><code>%%</code></td>
1328 <td>The percent sign</td></tr>
1329 <tr class="odd"><td><code>%...a</code></td>
1330 <td>Remote IP-address and port</td></tr>
1331 <tr><td><code>%...A</code></td>
1332 <td>Local IP-address and port</td></tr>
1333 <tr class="odd"><td><code>%...{name}e</code></td>
1334 <td>Request environment variable <code>name</code></td></tr>
1335 <tr><td><code>%...E</code></td>
1336 <td>APR/OS error status code and string</td></tr>
1337 <tr class="odd"><td><code>%...F</code></td>
1338 <td>Source file name and line number of the log call</td></tr>
1339 <tr><td><code>%...{name}i</code></td>
1340 <td>Request header <code>name</code></td></tr>
1341 <tr class="odd"><td><code>%...k</code></td>
1342 <td>Number of keep-alive requests on this connection</td></tr>
1343 <tr><td><code>%...l</code></td>
1344 <td>Loglevel of the message</td></tr>
1345 <tr class="odd"><td><code>%...L</code></td>
1346 <td>Log ID of the request</td></tr>
1347 <tr><td><code>%...{c}L</code></td>
1348 <td>Log ID of the connection</td></tr>
1349 <tr class="odd"><td><code>%...{C}L</code></td>
1350 <td>Log ID of the connection if used in connection scope, empty otherwise</td></tr>
1351 <tr><td><code>%...m</code></td>
1352 <td>Name of the module logging the message</td></tr>
1353 <tr class="odd"><td><code>%M</code></td>
1354 <td>The actual log message</td></tr>
1355 <tr><td><code>%...{name}n</code></td>
1356 <td>Request note <code>name</code></td></tr>
1357 <tr class="odd"><td><code>%...P</code></td>
1358 <td>Process ID of current process</td></tr>
1359 <tr><td><code>%...T</code></td>
1360 <td>Thread ID of current thread</td></tr>
1361 <tr class="odd"><td><code>%...t</code></td>
1362 <td>The current time</td></tr>
1363 <tr><td><code>%...{u}t</code></td>
1364 <td>The current time including micro-seconds</td></tr>
1365 <tr class="odd"><td><code>%...{cu}t</code></td>
1366 <td>The current time in compact ISO 8601 format, including
1367 micro-seconds</td></tr>
1368 <tr><td><code>%...v</code></td>
1369 <td>The canonical <code class="directive"><a href="#servername">ServerName</a></code>
1370 of the current server.</td></tr>
1371 <tr class="odd"><td><code>%...V</code></td>
1372 <td>The server name of the server serving the request according to the
1373 <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code>
1375 <tr><td><code>\ </code> (backslash space)</td>
1376 <td>Non-field delimiting space</td></tr>
1377 <tr class="odd"><td><code>% </code> (percent space)</td>
1378 <td>Field delimiter (no output)</td></tr>
1381 <p>The log ID format <code>%L</code> produces a unique id for a connection
1382 or request. This can be used to correlate which log lines belong to the
1383 same connection or request, which request happens on which connection.
1384 A <code>%L</code> format string is also available in
1385 <code class="module"><a href="../mod/mod_log_config.html">mod_log_config</a></code>, to allow to correlate access log entries
1386 with error log lines. If <code class="module"><a href="../mod/mod_unique_id.html">mod_unique_id</a></code> is loaded, its
1387 unique id will be used as log ID for requests.</p>
1389 <div class="example"><h3>Example (somewhat similar to default format)</h3><p><code>
1390 ErrorLogFormat "[%{u}t] [%-m:%l] [pid %P] %7F: %E: [client\ %a]
1391 %M% ,\ referer\ %{Referer}i"
1394 <div class="example"><h3>Example (similar to the 2.2.x format)</h3><p><code>
1395 ErrorLogFormat "[%t] [%l] %7F: %E: [client\ %a]
1396 %M% ,\ referer\ %{Referer}i"
1399 <div class="example"><h3>Advanced example with request/connection log IDs</h3><p><code>
1400 ErrorLogFormat "[%{uc}t] [%-m:%-l] [R:%L] [C:%{C}L] %7F: %E: %M"<br />
1401 ErrorLogFormat request "[%{uc}t] [R:%L] Request %k on C:%{c}L pid:%P tid:%T"<br />
1402 ErrorLogFormat request "[%{uc}t] [R:%L] UA:'%+{User-Agent}i'"<br />
1403 ErrorLogFormat request "[%{uc}t] [R:%L] Referer:'%+{Referer}i'"<br />
1404 ErrorLogFormat connection "[%{uc}t] [C:%{c}L] local\ %a remote\ %A"<br />
1410 <li><code class="directive"><a href="#errorlog">ErrorLog</a></code></li>
1411 <li><code class="directive"><a href="#loglevel">LogLevel</a></code></li>
1412 <li><a href="../logs.html">Apache HTTP Server Log Files</a></li>
1415 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1416 <div class="directive-section"><h2><a name="ExtendedStatus" id="ExtendedStatus">ExtendedStatus</a> <a name="extendedstatus" id="extendedstatus">Directive</a></h2>
1417 <table class="directive">
1418 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Keep track of extended status information for each
1420 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ExtendedStatus On|Off</code></td></tr>
1421 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ExtendedStatus Off[*]</code></td></tr>
1422 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
1423 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1424 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1426 <p>This option tracks additional data per worker about the
1427 currently executing request, and a utilization summary; you
1428 can see these variables during runtime by configuring
1429 <code class="module"><a href="../mod/mod_status.html">mod_status</a></code>. Note that other modules may
1430 rely on this scoreboard.</p>
1432 <p>This setting applies to the entire server, and cannot be
1433 enabled or disabled on a virtualhost-by-virtualhost basis.
1434 The collection of extended status information can slow down
1435 the server. Also note that this setting cannot be changed
1436 during a graceful restart.</p>
1439 <p>Note that loading <code class="module"><a href="../mod/mod_status.html">mod_status</a></code> will change
1440 the default behavior to ExtendedStatus On, while other
1441 third party modules may do the same. Such modules rely on
1442 collecting detailed information about the state of all workers.
1443 The default is changed by <code class="module"><a href="../mod/mod_status.html">mod_status</a></code> beginning
1444 with version 2.3.6; the previous default was always Off.</p>
1449 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1450 <div class="directive-section"><h2><a name="FileETag" id="FileETag">FileETag</a> <a name="fileetag" id="fileetag">Directive</a></h2>
1451 <table class="directive">
1452 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>File attributes used to create the ETag
1453 HTTP response header for static files</td></tr>
1454 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>FileETag <var>component</var> ...</code></td></tr>
1455 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>FileETag INode MTime Size</code></td></tr>
1456 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1457 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1458 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1459 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1462 The <code class="directive">FileETag</code> directive configures the file
1463 attributes that are used to create the <code>ETag</code> (entity
1464 tag) response header field when the document is based on a static file.
1465 (The <code>ETag</code> value is used in cache management to save
1466 network bandwidth.) The
1467 <code class="directive">FileETag</code> directive allows you to choose
1468 which of these -- if any -- should be used. The recognized keywords are:
1472 <dt><strong>INode</strong></dt>
1473 <dd>The file's i-node number will be included in the calculation</dd>
1474 <dt><strong>MTime</strong></dt>
1475 <dd>The date and time the file was last modified will be included</dd>
1476 <dt><strong>Size</strong></dt>
1477 <dd>The number of bytes in the file will be included</dd>
1478 <dt><strong>All</strong></dt>
1479 <dd>All available fields will be used. This is equivalent to:
1480 <div class="example"><p><code>FileETag INode MTime Size</code></p></div></dd>
1481 <dt><strong>None</strong></dt>
1482 <dd>If a document is file-based, no <code>ETag</code> field will be
1483 included in the response</dd>
1486 <p>The <code>INode</code>, <code>MTime</code>, and <code>Size</code>
1487 keywords may be prefixed with either <code>+</code> or <code>-</code>,
1488 which allow changes to be made to the default setting inherited
1489 from a broader scope. Any keyword appearing without such a prefix
1490 immediately and completely cancels the inherited setting.</p>
1492 <p>If a directory's configuration includes
1493 <code>FileETag INode MTime Size</code>, and a
1494 subdirectory's includes <code>FileETag -INode</code>,
1495 the setting for that subdirectory (which will be inherited by
1496 any sub-subdirectories that don't override it) will be equivalent to
1497 <code>FileETag MTime Size</code>.</p>
1498 <div class="warning"><h3>Warning</h3>
1499 Do not change the default for directories or locations that have WebDAV
1500 enabled and use <code class="module"><a href="../mod/mod_dav_fs.html">mod_dav_fs</a></code> as a storage provider.
1501 <code class="module"><a href="../mod/mod_dav_fs.html">mod_dav_fs</a></code> uses <code>INode MTime Size</code>
1502 as a fixed format for <code>ETag</code> comparisons on conditional requests.
1503 These conditional requests will break if the <code>ETag</code> format is
1504 changed via <code class="directive">FileETag</code>.
1506 <div class="note"><h3>Server Side Includes</h3>
1507 An ETag is not generated for responses parsed by <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>,
1508 since the response entity can change without a change of the INode, MTime, or Size
1509 of the static file with embedded SSI directives.
1514 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1515 <div class="directive-section"><h2><a name="Files" id="Files"><Files></a> <a name="files" id="files">Directive</a></h2>
1516 <table class="directive">
1517 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply to matched
1519 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Files <var>filename</var>> ... </Files></code></td></tr>
1520 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1521 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1522 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1523 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1525 <p>The <code class="directive"><Files></code> directive
1526 limits the scope of the enclosed directives by filename. It is comparable
1527 to the <code class="directive"><a href="#directory"><Directory></a></code>
1528 and <code class="directive"><a href="#location"><Location></a></code>
1529 directives. It should be matched with a <code></Files></code>
1530 directive. The directives given within this section will be applied to
1531 any object with a basename (last component of filename) matching the
1532 specified filename. <code class="directive"><Files></code>
1533 sections are processed in the order they appear in the
1534 configuration file, after the <code class="directive"><a href="#directory"><Directory></a></code> sections and
1535 <code>.htaccess</code> files are read, but before <code class="directive"><a href="#location"><Location></a></code> sections. Note
1536 that <code class="directive"><Files></code> can be nested
1537 inside <code class="directive"><a href="#directory"><Directory></a></code> sections to restrict the
1538 portion of the filesystem they apply to.</p>
1540 <p>The <var>filename</var> argument should include a filename, or
1541 a wild-card string, where <code>?</code> matches any single character,
1542 and <code>*</code> matches any sequences of characters.
1543 <a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular expressions</a>
1544 can also be used, with the addition of the
1545 <code>~</code> character. For example:</p>
1547 <div class="example"><p><code>
1548 <Files ~ "\.(gif|jpe?g|png)$">
1551 <p>would match most common Internet graphics formats. <code class="directive"><a href="#filesmatch"><FilesMatch></a></code> is preferred,
1554 <p>Note that unlike <code class="directive"><a href="#directory"><Directory></a></code> and <code class="directive"><a href="#location"><Location></a></code> sections, <code class="directive"><Files></code> sections can be used inside
1555 <code>.htaccess</code> files. This allows users to control access to
1556 their own files, at a file-by-file level.</p>
1561 <li><a href="../sections.html">How <Directory>, <Location>
1562 and <Files> sections work</a> for an explanation of how these
1563 different sections are combined when a request is received</li>
1566 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1567 <div class="directive-section"><h2><a name="FilesMatch" id="FilesMatch"><FilesMatch></a> <a name="filesmatch" id="filesmatch">Directive</a></h2>
1568 <table class="directive">
1569 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply to regular-expression matched
1571 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><FilesMatch <var>regex</var>> ... </FilesMatch></code></td></tr>
1572 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1573 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1574 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1575 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1577 <p>The <code class="directive"><FilesMatch></code> directive
1578 limits the scope of the enclosed directives by filename, just as the
1579 <code class="directive"><a href="#files"><Files></a></code> directive
1580 does. However, it accepts a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular
1581 expression</a>. For example:</p>
1583 <div class="example"><p><code>
1584 <FilesMatch "\.(gif|jpe?g|png)$">
1587 <p>would match most common Internet graphics formats.</p>
1591 <li><a href="../sections.html">How <Directory>, <Location>
1592 and <Files> sections work</a> for an explanation of how these
1593 different sections are combined when a request is received</li>
1596 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1597 <div class="directive-section"><h2><a name="ForceType" id="ForceType">ForceType</a> <a name="forcetype" id="forcetype">Directive</a></h2>
1598 <table class="directive">
1599 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Forces all matching files to be served with the specified
1600 media type in the HTTP Content-Type header field</td></tr>
1601 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ForceType <var>media-type</var>|None</code></td></tr>
1602 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
1603 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1604 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1605 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1606 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Moved to the core in Apache httpd 2.0</td></tr>
1608 <p>When placed into an <code>.htaccess</code> file or a
1609 <code class="directive"><a href="#directory"><Directory></a></code>, or
1610 <code class="directive"><a href="#location"><Location></a></code> or
1611 <code class="directive"><a href="#files"><Files></a></code>
1612 section, this directive forces all matching files to be served
1613 with the content type identification given by
1614 <var>media-type</var>. For example, if you had a directory full of
1615 GIF files, but did not want to label them all with <code>.gif</code>,
1616 you might want to use:</p>
1618 <div class="example"><p><code>
1622 <p>Note that this directive overrides other indirect media type
1623 associations defined in mime.types or via the
1624 <code class="directive"><a href="../mod/mod_mime.html#addtype">AddType</a></code>.</p>
1626 <p>You can also override more general
1627 <code class="directive">ForceType</code> settings
1628 by using the value of <code>None</code>:</p>
1630 <div class="example"><p><code>
1631 # force all files to be image/gif:<br />
1632 <Location /images><br />
1633 <span class="indent">
1634 ForceType image/gif<br />
1636 </Location><br />
1638 # but normal mime-type associations here:<br />
1639 <Location /images/mixed><br />
1640 <span class="indent">
1641 ForceType None<br />
1646 <p>This directive primarily overrides the content types generated for
1647 static files served out of the filesystem. For resources other than
1648 static files, where the generator of the response typically specifies
1649 a Content-Type, this directive has no effect.</p>
1653 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1654 <div class="directive-section"><h2><a name="GprofDir" id="GprofDir">GprofDir</a> <a name="gprofdir" id="gprofdir">Directive</a></h2>
1655 <table class="directive">
1656 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Directory to write gmon.out profiling data to. </td></tr>
1657 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>GprofDir <var>/tmp/gprof/</var>|<var>/tmp/gprof/</var>%</code></td></tr>
1658 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1659 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1660 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1662 <p>When the server has been compiled with gprof profiling suppport,
1663 <code class="directive">GprofDir</code> causes <code>gmon.out</code> files to
1664 be written to the specified directory when the process exits. If the
1665 argument ends with a percent symbol ('%'), subdirectories are created
1666 for each process id.</p>
1668 <p>This directive currently only works with the <code class="module"><a href="../mod/prefork.html">prefork</a></code>
1672 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1673 <div class="directive-section"><h2><a name="HostnameLookups" id="HostnameLookups">HostnameLookups</a> <a name="hostnamelookups" id="hostnamelookups">Directive</a></h2>
1674 <table class="directive">
1675 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables DNS lookups on client IP addresses</td></tr>
1676 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>HostnameLookups On|Off|Double</code></td></tr>
1677 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>HostnameLookups Off</code></td></tr>
1678 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1679 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1680 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1682 <p>This directive enables DNS lookups so that host names can be
1683 logged (and passed to CGIs/SSIs in <code>REMOTE_HOST</code>).
1684 The value <code>Double</code> refers to doing double-reverse
1685 DNS lookup. That is, after a reverse lookup is performed, a forward
1686 lookup is then performed on that result. At least one of the IP
1687 addresses in the forward lookup must match the original
1688 address. (In "tcpwrappers" terminology this is called
1689 <code>PARANOID</code>.)</p>
1691 <p>Regardless of the setting, when <code class="module"><a href="../mod/mod_authz_host.html">mod_authz_host</a></code> is
1692 used for controlling access by hostname, a double reverse lookup
1693 will be performed. This is necessary for security. Note that the
1694 result of this double-reverse isn't generally available unless you
1695 set <code>HostnameLookups Double</code>. For example, if only
1696 <code>HostnameLookups On</code> and a request is made to an object
1697 that is protected by hostname restrictions, regardless of whether
1698 the double-reverse fails or not, CGIs will still be passed the
1699 single-reverse result in <code>REMOTE_HOST</code>.</p>
1701 <p>The default is <code>Off</code> in order to save the network
1702 traffic for those sites that don't truly need the reverse
1703 lookups done. It is also better for the end users because they
1704 don't have to suffer the extra latency that a lookup entails.
1705 Heavily loaded sites should leave this directive
1706 <code>Off</code>, since DNS lookups can take considerable
1707 amounts of time. The utility <code class="program"><a href="../programs/logresolve.html">logresolve</a></code>, compiled by
1708 default to the <code>bin</code> subdirectory of your installation
1709 directory, can be used to look up host names from logged IP addresses
1713 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1714 <div class="directive-section"><h2><a name="If" id="If"><If></a> <a name="if" id="if">Directive</a></h2>
1715 <table class="directive">
1716 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if a condition is
1717 satisfied by a request at runtime</td></tr>
1718 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><If <var>expression</var>> ... </If></code></td></tr>
1719 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1720 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1721 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1722 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1724 <p>The <code class="directive"><If></code> directive
1725 evaluates an expression at runtime, and applies the enclosed
1726 directives if and only if the expression evaluates to true.
1729 <div class="example"><p><code>
1730 <If "-z req('Host')">
1733 <p>would match HTTP/1.0 requests without a <var>Host:</var> header.
1734 Expressions may contain various shell-like operators for string
1735 comparison (<code>=</code>, <code>!=</code>, <code><</code>, ...),
1736 integer comparison (<code>-eq</code>, <code>-ne</code>, ...),
1737 and others (<code>-n</code>, <code>-z</code>, <code>-f</code>, ...).
1738 It is also possible to use regular expressions, </p>
1740 <div class="example"><p><code>
1741 <If "%{QUERY_STRING =~ /(delete|commit)=.*?elem/">
1744 <p>shell-like pattern matches and many other operations. These operations
1745 can be done on request headers (<code>req</code>), environment variables
1746 (<code>env</code>), and a large number of other properties. The full
1747 documentation is available in <a href="../expr.html">Expressions in
1748 Apache HTTP Server</a>.</p>
1753 <li><a href="../expr.html">Expressions in Apache HTTP Server</a>,
1754 for a complete reference and more examples.</li>
1755 <li><code class="directive"><a href="#elseif"><ElseIf></a></code></li>
1756 <li><code class="directive"><a href="#else"><Else></a></code></li>
1757 <li><a href="../sections.html">How <Directory>, <Location>,
1758 <Files> sections work</a> for an explanation of how these
1759 different sections are combined when a request is received.
1760 <code class="directive"><If></code>,
1761 <code class="directive"><ElseIf></code>, and
1762 <code class="directive"><Else></code> are applied last.</li>
1765 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1766 <div class="directive-section"><h2><a name="IfDefine" id="IfDefine"><IfDefine></a> <a name="ifdefine" id="ifdefine">Directive</a></h2>
1767 <table class="directive">
1768 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Encloses directives that will be processed only
1769 if a test is true at startup</td></tr>
1770 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><IfDefine [!]<var>parameter-name</var>> ...
1771 </IfDefine></code></td></tr>
1772 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1773 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1774 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1775 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1777 <p>The <code><IfDefine <var>test</var>>...</IfDefine>
1778 </code> section is used to mark directives that are conditional. The
1779 directives within an <code class="directive"><IfDefine></code>
1780 section are only processed if the <var>test</var> is true. If <var>
1781 test</var> is false, everything between the start and end markers is
1784 <p>The <var>test</var> in the <code class="directive"><IfDefine></code> section directive can be one of two forms:</p>
1787 <li><var>parameter-name</var></li>
1789 <li><code>!</code><var>parameter-name</var></li>
1792 <p>In the former case, the directives between the start and end
1793 markers are only processed if the parameter named
1794 <var>parameter-name</var> is defined. The second format reverses
1795 the test, and only processes the directives if
1796 <var>parameter-name</var> is <strong>not</strong> defined.</p>
1798 <p>The <var>parameter-name</var> argument is a define as given on the
1799 <code class="program"><a href="../programs/httpd.html">httpd</a></code> command line via <code>-D<var>parameter</var>
1800 </code> at the time the server was started or by the <code class="directive"><a href="#define">Define</a></code> directive.</p>
1802 <p><code class="directive"><IfDefine></code> sections are
1803 nest-able, which can be used to implement simple
1804 multiple-parameter tests. Example:</p>
1806 <div class="example"><p><code>
1807 httpd -DReverseProxy -DUseCache -DMemCache ...<br />
1810 <IfDefine ReverseProxy><br />
1811 <span class="indent">
1812 LoadModule proxy_module modules/mod_proxy.so<br />
1813 LoadModule proxy_http_module modules/mod_proxy_http.so<br />
1814 <IfDefine UseCache><br />
1815 <span class="indent">
1816 LoadModule cache_module modules/mod_cache.so<br />
1817 <IfDefine MemCache><br />
1818 <span class="indent">
1819 LoadModule mem_cache_module modules/mod_mem_cache.so<br />
1821 </IfDefine><br />
1822 <IfDefine !MemCache><br />
1823 <span class="indent">
1824 LoadModule cache_disk_module modules/mod_cache_disk.so<br />
1834 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1835 <div class="directive-section"><h2><a name="IfModule" id="IfModule"><IfModule></a> <a name="ifmodule" id="ifmodule">Directive</a></h2>
1836 <table class="directive">
1837 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Encloses directives that are processed conditional on the
1838 presence or absence of a specific module</td></tr>
1839 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><IfModule [!]<var>module-file</var>|<var>module-identifier</var>> ...
1840 </IfModule></code></td></tr>
1841 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1842 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1843 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1844 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1845 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Module identifiers are available in version 2.1 and
1848 <p>The <code><IfModule <var>test</var>>...</IfModule></code>
1849 section is used to mark directives that are conditional on the presence of
1850 a specific module. The directives within an <code class="directive"><IfModule></code> section are only processed if the <var>test</var>
1851 is true. If <var>test</var> is false, everything between the start and
1852 end markers is ignored.</p>
1854 <p>The <var>test</var> in the <code class="directive"><IfModule></code> section directive can be one of two forms:</p>
1857 <li><var>module</var></li>
1859 <li>!<var>module</var></li>
1862 <p>In the former case, the directives between the start and end
1863 markers are only processed if the module named <var>module</var>
1864 is included in Apache httpd -- either compiled in or
1865 dynamically loaded using <code class="directive"><a href="../mod/mod_so.html#loadmodule">LoadModule</a></code>. The second format reverses the test,
1866 and only processes the directives if <var>module</var> is
1867 <strong>not</strong> included.</p>
1869 <p>The <var>module</var> argument can be either the module identifier or
1870 the file name of the module, at the time it was compiled. For example,
1871 <code>rewrite_module</code> is the identifier and
1872 <code>mod_rewrite.c</code> is the file name. If a module consists of
1873 several source files, use the name of the file containing the string
1874 <code>STANDARD20_MODULE_STUFF</code>.</p>
1876 <p><code class="directive"><IfModule></code> sections are
1877 nest-able, which can be used to implement simple multiple-module
1880 <div class="note">This section should only be used if you need to have one
1881 configuration file that works whether or not a specific module
1882 is available. In normal operation, directives need not be
1883 placed in <code class="directive"><IfModule></code>
1887 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1888 <div class="directive-section"><h2><a name="Include" id="Include">Include</a> <a name="include" id="include">Directive</a></h2>
1889 <table class="directive">
1890 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Includes other configuration files from within
1891 the server configuration files</td></tr>
1892 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Include [<var>optional</var>|<var>strict</var>] <var>file-path</var>|<var>directory-path</var>|<var>wildcard</var></code></td></tr>
1893 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
1894 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1895 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1896 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Wildcard matching available in 2.0.41 and later, directory
1897 wildcard matching available in 2.3.6 and later</td></tr>
1899 <p>This directive allows inclusion of other configuration files
1900 from within the server configuration files.</p>
1902 <p>Shell-style (<code>fnmatch()</code>) wildcard characters can be used
1903 in the filename or directory parts of the path to include several files
1904 at once, in alphabetical order. In addition, if
1905 <code class="directive">Include</code> points to a directory, rather than a file,
1906 Apache httpd will read all files in that directory and any subdirectory.
1907 However, including entire directories is not recommended, because it is
1908 easy to accidentally leave temporary files in a directory that can cause
1909 <code class="program"><a href="../programs/httpd.html">httpd</a></code> to fail. Instead, we encourage you to use the
1910 wildcard syntax shown below, to include files that match a particular
1911 pattern, such as *.conf, for example.</p>
1913 <p>When a wildcard is specified for a <strong>file</strong> component of
1914 the path, and no file matches the wildcard, the
1915 <code class="directive"><a href="#include">Include</a></code>
1916 directive will be <strong>silently ignored</strong>. When a wildcard is
1917 specified for a <strong>directory</strong> component of the path, and
1918 no directory matches the wildcard, the
1919 <code class="directive"><a href="#include">Include</a></code> directive will
1920 <strong>fail with an error</strong> saying the directory cannot be found.
1923 <p>For further control over the behaviour of the server when no files or
1924 directories match, prefix the path with the modifiers <var>optional</var>
1925 or <var>strict</var>. If <var>optional</var> is specified, any wildcard
1926 file or directory that does not match will be silently ignored. If
1927 <var>strict</var> is specified, any wildcard file or directory that does
1928 not match at least one file will cause server startup to fail.</p>
1930 <p>When a directory or file component of the path is
1931 specified exactly, and that directory or file does not exist,
1932 <code class="directive"><a href="#include">Include</a></code> directive will fail with an
1933 error saying the file or directory cannot be found.</p>
1935 <p>The file path specified may be an absolute path, or may be relative
1936 to the <code class="directive"><a href="#serverroot">ServerRoot</a></code> directory.</p>
1940 <div class="example"><p><code>
1941 Include /usr/local/apache2/conf/ssl.conf<br />
1942 Include /usr/local/apache2/conf/vhosts/*.conf
1945 <p>Or, providing paths relative to your <code class="directive"><a href="#serverroot">ServerRoot</a></code> directory:</p>
1947 <div class="example"><p><code>
1948 Include conf/ssl.conf<br />
1949 Include conf/vhosts/*.conf
1952 <p>Wildcards may be included in the directory or file portion of the
1953 path. In the following example, the server will fail to load if no
1954 directories match conf/vhosts/*, but will load successfully if no
1955 files match *.conf.</p>
1957 <div class="example"><p><code>
1958 Include conf/vhosts/*/vhost.conf<br />
1959 Include conf/vhosts/*/*.conf
1962 <p>In this example, the server will fail to load if either
1963 conf/vhosts/* matches no directories, or if *.conf matches no files:</p>
1965 <div class="example"><p><code>
1966 Include strict conf/vhosts/*/*.conf
1969 <p>In this example, the server load successfully if either conf/vhosts/*
1970 matches no directories, or if *.conf matches no files:</p>
1972 <div class="example"><p><code>
1973 Include optional conf/vhosts/*/*.conf
1979 <li><code class="program"><a href="../programs/apachectl.html">apachectl</a></code></li>
1982 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1983 <div class="directive-section"><h2><a name="KeepAlive" id="KeepAlive">KeepAlive</a> <a name="keepalive" id="keepalive">Directive</a></h2>
1984 <table class="directive">
1985 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables HTTP persistent connections</td></tr>
1986 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>KeepAlive On|Off</code></td></tr>
1987 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>KeepAlive On</code></td></tr>
1988 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1989 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1990 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1992 <p>The Keep-Alive extension to HTTP/1.0 and the persistent
1993 connection feature of HTTP/1.1 provide long-lived HTTP sessions
1994 which allow multiple requests to be sent over the same TCP
1995 connection. In some cases this has been shown to result in an
1996 almost 50% speedup in latency times for HTML documents with
1997 many images. To enable Keep-Alive connections, set
1998 <code>KeepAlive On</code>.</p>
2000 <p>For HTTP/1.0 clients, Keep-Alive connections will only be
2001 used if they are specifically requested by a client. In
2002 addition, a Keep-Alive connection with an HTTP/1.0 client can
2003 only be used when the length of the content is known in
2004 advance. This implies that dynamic content such as CGI output,
2005 SSI pages, and server-generated directory listings will
2006 generally not use Keep-Alive connections to HTTP/1.0 clients.
2007 For HTTP/1.1 clients, persistent connections are the default
2008 unless otherwise specified. If the client requests it, chunked
2009 encoding will be used in order to send content of unknown
2010 length over persistent connections.</p>
2012 <p>When a client uses a Keep-Alive connection it will be counted
2013 as a single "request" for the <code class="directive"><a href="../mod/mpm_common.html#maxconnectionsperchild">MaxConnectionsPerChild</a></code> directive, regardless
2014 of how many requests are sent using the connection.</p>
2018 <li><code class="directive"><a href="#maxkeepaliverequests">MaxKeepAliveRequests</a></code></li>
2021 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2022 <div class="directive-section"><h2><a name="KeepAliveTimeout" id="KeepAliveTimeout">KeepAliveTimeout</a> <a name="keepalivetimeout" id="keepalivetimeout">Directive</a></h2>
2023 <table class="directive">
2024 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Amount of time the server will wait for subsequent
2025 requests on a persistent connection</td></tr>
2026 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>KeepAliveTimeout <var>num</var>[ms]</code></td></tr>
2027 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>KeepAliveTimeout 5</code></td></tr>
2028 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2029 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2030 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2031 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Specifying a value in milliseconds is available in
2032 Apache httpd 2.3.2 and later</td></tr>
2034 <p>The number of seconds Apache httpd will wait for a subsequent
2035 request before closing the connection. By adding a postfix of ms the
2036 timeout can be also set in milliseconds. Once a request has been
2037 received, the timeout value specified by the
2038 <code class="directive"><a href="#timeout">Timeout</a></code> directive applies.</p>
2040 <p>Setting <code class="directive">KeepAliveTimeout</code> to a high value
2041 may cause performance problems in heavily loaded servers. The
2042 higher the timeout, the more server processes will be kept
2043 occupied waiting on connections with idle clients.</p>
2045 <p>In a name-based virtual host context, the value of the first
2046 defined virtual host best matching the local IP and port will be used.</p>
2049 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2050 <div class="directive-section"><h2><a name="Limit" id="Limit"><Limit></a> <a name="limit" id="limit">Directive</a></h2>
2051 <table class="directive">
2052 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restrict enclosed access controls to only certain HTTP
2054 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Limit <var>method</var> [<var>method</var>] ... > ...
2055 </Limit></code></td></tr>
2056 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
2057 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig, Limit</td></tr>
2058 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2059 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2061 <p>Access controls are normally effective for
2062 <strong>all</strong> access methods, and this is the usual
2063 desired behavior. <strong>In the general case, access control
2064 directives should not be placed within a
2065 <code class="directive"><Limit></code> section.</strong></p>
2067 <p>The purpose of the <code class="directive"><Limit></code>
2068 directive is to restrict the effect of the access controls to the
2069 nominated HTTP methods. For all other methods, the access
2070 restrictions that are enclosed in the <code class="directive"><Limit></code> bracket <strong>will have no
2071 effect</strong>. The following example applies the access control
2072 only to the methods <code>POST</code>, <code>PUT</code>, and
2073 <code>DELETE</code>, leaving all other methods unprotected:</p>
2075 <div class="example"><p><code>
2076 <Limit POST PUT DELETE><br />
2077 <span class="indent">
2078 Require valid-user<br />
2083 <p>The method names listed can be one or more of: <code>GET</code>,
2084 <code>POST</code>, <code>PUT</code>, <code>DELETE</code>,
2085 <code>CONNECT</code>, <code>OPTIONS</code>,
2086 <code>PATCH</code>, <code>PROPFIND</code>, <code>PROPPATCH</code>,
2087 <code>MKCOL</code>, <code>COPY</code>, <code>MOVE</code>,
2088 <code>LOCK</code>, and <code>UNLOCK</code>. <strong>The method name is
2089 case-sensitive.</strong> If <code>GET</code> is used it will also
2090 restrict <code>HEAD</code> requests. The <code>TRACE</code> method
2091 cannot be limited (see <code class="directive"><a href="#traceenable">TraceEnable</a></code>).</p>
2093 <div class="warning">A <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> section should always be
2094 used in preference to a <code class="directive"><Limit></code>
2095 section when restricting access, since a <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> section provides protection
2096 against arbitrary methods.</div>
2098 <p>The <code class="directive"><Limit></code> and
2099 <code class="directive"><a href="#limitexcept"><LimitExcept></a></code>
2100 directives may be nested. In this case, each successive level of
2101 <code class="directive"><Limit></code> or <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> directives must
2102 further restrict the set of methods to which access controls apply.</p>
2104 <div class="warning">When using
2105 <code class="directive"><Limit></code> or
2106 <code class="directive"><LimitExcept></code> directives with
2107 the <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code> directive,
2108 note that the first <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code>
2109 to succeed authorizes the request, regardless of the presence of other
2110 <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code> directives.</div>
2112 <p>For example, given the following configuration, all users will
2113 be authorized for <code>POST</code> requests, and the
2114 <code>Require group editors</code> directive will be ignored
2117 <div class="example"><p><code>
2118 <LimitExcept GET>
2119 <span class="indent">
2122 </LimitExcept><br />
2124 <span class="indent">
2125 Require group editors
2131 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2132 <div class="directive-section"><h2><a name="LimitExcept" id="LimitExcept"><LimitExcept></a> <a name="limitexcept" id="limitexcept">Directive</a></h2>
2133 <table class="directive">
2134 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restrict access controls to all HTTP methods
2135 except the named ones</td></tr>
2136 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><LimitExcept <var>method</var> [<var>method</var>] ... > ...
2137 </LimitExcept></code></td></tr>
2138 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
2139 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig, Limit</td></tr>
2140 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2141 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2143 <p><code class="directive"><LimitExcept></code> and
2144 <code></LimitExcept></code> are used to enclose
2145 a group of access control directives which will then apply to any
2146 HTTP access method <strong>not</strong> listed in the arguments;
2147 i.e., it is the opposite of a <code class="directive"><a href="#limit"><Limit></a></code> section and can be used to control
2148 both standard and nonstandard/unrecognized methods. See the
2149 documentation for <code class="directive"><a href="#limit"><Limit></a></code> for more details.</p>
2153 <div class="example"><p><code>
2154 <LimitExcept POST GET><br />
2155 <span class="indent">
2156 Require valid-user<br />
2158 </LimitExcept>
2163 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2164 <div class="directive-section"><h2><a name="LimitInternalRecursion" id="LimitInternalRecursion">LimitInternalRecursion</a> <a name="limitinternalrecursion" id="limitinternalrecursion">Directive</a></h2>
2165 <table class="directive">
2166 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determine maximum number of internal redirects and nested
2167 subrequests</td></tr>
2168 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitInternalRecursion <var>number</var> [<var>number</var>]</code></td></tr>
2169 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitInternalRecursion 10</code></td></tr>
2170 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2171 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2172 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2173 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache httpd 2.0.47 and later</td></tr>
2175 <p>An internal redirect happens, for example, when using the <code class="directive"><a href="../mod/mod_actions.html#action">Action</a></code> directive, which internally
2176 redirects the original request to a CGI script. A subrequest is Apache httpd's
2177 mechanism to find out what would happen for some URI if it were requested.
2178 For example, <code class="module"><a href="../mod/mod_dir.html">mod_dir</a></code> uses subrequests to look for the
2179 files listed in the <code class="directive"><a href="../mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>
2182 <p><code class="directive">LimitInternalRecursion</code> prevents the server
2183 from crashing when entering an infinite loop of internal redirects or
2184 subrequests. Such loops are usually caused by misconfigurations.</p>
2186 <p>The directive stores two different limits, which are evaluated on
2187 per-request basis. The first <var>number</var> is the maximum number of
2188 internal redirects, that may follow each other. The second <var>number</var>
2189 determines, how deep subrequests may be nested. If you specify only one
2190 <var>number</var>, it will be assigned to both limits.</p>
2192 <div class="example"><h3>Example</h3><p><code>
2193 LimitInternalRecursion 5
2197 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2198 <div class="directive-section"><h2><a name="LimitRequestBody" id="LimitRequestBody">LimitRequestBody</a> <a name="limitrequestbody" id="limitrequestbody">Directive</a></h2>
2199 <table class="directive">
2200 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restricts the total size of the HTTP request body sent
2201 from the client</td></tr>
2202 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestBody <var>bytes</var></code></td></tr>
2203 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestBody 0</code></td></tr>
2204 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2205 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2206 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2207 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2209 <p>This directive specifies the number of <var>bytes</var> from 0
2210 (meaning unlimited) to 2147483647 (2GB) that are allowed in a
2211 request body. See the note below for the limited applicability
2212 to proxy requests.</p>
2214 <p>The <code class="directive">LimitRequestBody</code> directive allows
2215 the user to set a limit on the allowed size of an HTTP request
2216 message body within the context in which the directive is given
2217 (server, per-directory, per-file or per-location). If the client
2218 request exceeds that limit, the server will return an error
2219 response instead of servicing the request. The size of a normal
2220 request message body will vary greatly depending on the nature of
2221 the resource and the methods allowed on that resource. CGI scripts
2222 typically use the message body for retrieving form information.
2223 Implementations of the <code>PUT</code> method will require
2224 a value at least as large as any representation that the server
2225 wishes to accept for that resource.</p>
2227 <p>This directive gives the server administrator greater
2228 control over abnormal client request behavior, which may be
2229 useful for avoiding some forms of denial-of-service
2232 <p>If, for example, you are permitting file upload to a particular
2233 location, and wish to limit the size of the uploaded file to 100K,
2234 you might use the following directive:</p>
2236 <div class="example"><p><code>
2237 LimitRequestBody 102400
2240 <div class="note"><p>For a full description of how this directive is interpreted by
2241 proxy requests, see the <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> documentation.</p>
2246 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2247 <div class="directive-section"><h2><a name="LimitRequestFields" id="LimitRequestFields">LimitRequestFields</a> <a name="limitrequestfields" id="limitrequestfields">Directive</a></h2>
2248 <table class="directive">
2249 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the number of HTTP request header fields that
2250 will be accepted from the client</td></tr>
2251 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestFields <var>number</var></code></td></tr>
2252 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestFields 100</code></td></tr>
2253 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2254 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2255 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2257 <p><var>Number</var> is an integer from 0 (meaning unlimited) to
2258 32767. The default value is defined by the compile-time
2259 constant <code>DEFAULT_LIMIT_REQUEST_FIELDS</code> (100 as
2262 <p>The <code class="directive">LimitRequestFields</code> directive allows
2263 the server administrator to modify the limit on the number of
2264 request header fields allowed in an HTTP request. A server needs
2265 this value to be larger than the number of fields that a normal
2266 client request might include. The number of request header fields
2267 used by a client rarely exceeds 20, but this may vary among
2268 different client implementations, often depending upon the extent
2269 to which a user has configured their browser to support detailed
2270 content negotiation. Optional HTTP extensions are often expressed
2271 using request header fields.</p>
2273 <p>This directive gives the server administrator greater
2274 control over abnormal client request behavior, which may be
2275 useful for avoiding some forms of denial-of-service attacks.
2276 The value should be increased if normal clients see an error
2277 response from the server that indicates too many fields were
2278 sent in the request.</p>
2282 <div class="example"><p><code>
2283 LimitRequestFields 50
2286 <div class="warning"><h3>Warning</h3>
2287 <p> When name-based virtual hosting is used, the value for this
2288 directive is taken from the default (first-listed) virtual host for the
2289 local IP and port combination</p>.
2294 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2295 <div class="directive-section"><h2><a name="LimitRequestFieldSize" id="LimitRequestFieldSize">LimitRequestFieldSize</a> <a name="limitrequestfieldsize" id="limitrequestfieldsize">Directive</a></h2>
2296 <table class="directive">
2297 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the size of the HTTP request header allowed from the
2299 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestFieldSize <var>bytes</var></code></td></tr>
2300 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestFieldSize 8190</code></td></tr>
2301 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2302 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2303 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2305 <p>This directive specifies the number of <var>bytes</var>
2306 that will be allowed in an HTTP request header.</p>
2308 <p>The <code class="directive">LimitRequestFieldSize</code> directive
2309 allows the server administrator to reduce or increase the limit
2310 on the allowed size of an HTTP request header field. A server
2311 needs this value to be large enough to hold any one header field
2312 from a normal client request. The size of a normal request header
2313 field will vary greatly among different client implementations,
2314 often depending upon the extent to which a user has configured
2315 their browser to support detailed content negotiation. SPNEGO
2316 authentication headers can be up to 12392 bytes.</p>
2318 <p>This directive gives the server administrator greater
2319 control over abnormal client request behavior, which may be
2320 useful for avoiding some forms of denial-of-service attacks.</p>
2324 <div class="example"><p><code>
2325 LimitRequestFieldSize 4094
2328 <div class="note">Under normal conditions, the value should not be changed from
2331 <div class="warning"><h3>Warning</h3>
2332 <p> When name-based virtual hosting is used, the value for this
2333 directive is taken from the default (first-listed) virtual host best
2334 matching the current IP address and port combination.</p>
2338 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2339 <div class="directive-section"><h2><a name="LimitRequestLine" id="LimitRequestLine">LimitRequestLine</a> <a name="limitrequestline" id="limitrequestline">Directive</a></h2>
2340 <table class="directive">
2341 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limit the size of the HTTP request line that will be accepted
2342 from the client</td></tr>
2343 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestLine <var>bytes</var></code></td></tr>
2344 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestLine 8190</code></td></tr>
2345 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2346 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2347 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2349 <p>This directive sets the number of <var>bytes</var> that will be
2350 allowed on the HTTP request-line.</p>
2352 <p>The <code class="directive">LimitRequestLine</code> directive allows
2353 the server administrator to reduce or increase the limit on the allowed size
2354 of a client's HTTP request-line. Since the request-line consists of the
2355 HTTP method, URI, and protocol version, the
2356 <code class="directive">LimitRequestLine</code> directive places a
2357 restriction on the length of a request-URI allowed for a request
2358 on the server. A server needs this value to be large enough to
2359 hold any of its resource names, including any information that
2360 might be passed in the query part of a <code>GET</code> request.</p>
2362 <p>This directive gives the server administrator greater
2363 control over abnormal client request behavior, which may be
2364 useful for avoiding some forms of denial-of-service attacks.</p>
2368 <div class="example"><p><code>
2369 LimitRequestLine 4094
2372 <div class="note">Under normal conditions, the value should not be changed from
2375 <div class="warning"><h3>Warning</h3>
2376 <p> When name-based virtual hosting is used, the value for this
2377 directive is taken from the default (first-listed) virtual host best
2378 matching the current IP address and port combination.</p>
2383 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2384 <div class="directive-section"><h2><a name="LimitXMLRequestBody" id="LimitXMLRequestBody">LimitXMLRequestBody</a> <a name="limitxmlrequestbody" id="limitxmlrequestbody">Directive</a></h2>
2385 <table class="directive">
2386 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the size of an XML-based request body</td></tr>
2387 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitXMLRequestBody <var>bytes</var></code></td></tr>
2388 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitXMLRequestBody 1000000</code></td></tr>
2389 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2390 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2391 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2392 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2394 <p>Limit (in bytes) on maximum size of an XML-based request
2395 body. A value of <code>0</code> will disable any checking.</p>
2399 <div class="example"><p><code>
2400 LimitXMLRequestBody 0
2405 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2406 <div class="directive-section"><h2><a name="Location" id="Location"><Location></a> <a name="location" id="location">Directive</a></h2>
2407 <table class="directive">
2408 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Applies the enclosed directives only to matching
2410 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Location
2411 <var>URL-path</var>|<var>URL</var>> ... </Location></code></td></tr>
2412 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2413 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2414 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2416 <p>The <code class="directive"><Location></code> directive
2417 limits the scope of the enclosed directives by URL. It is similar to the
2418 <code class="directive"><a href="#directory"><Directory></a></code>
2419 directive, and starts a subsection which is terminated with a
2420 <code></Location></code> directive. <code class="directive"><Location></code> sections are processed in the
2421 order they appear in the configuration file, after the <code class="directive"><a href="#directory"><Directory></a></code> sections and
2422 <code>.htaccess</code> files are read, and after the <code class="directive"><a href="#files"><Files></a></code> sections.</p>
2424 <p><code class="directive"><Location></code> sections operate
2425 completely outside the filesystem. This has several consequences.
2426 Most importantly, <code class="directive"><Location></code>
2427 directives should not be used to control access to filesystem
2428 locations. Since several different URLs may map to the same
2429 filesystem location, such access controls may by circumvented.</p>
2431 <p>The enclosed directives will be applied to the request if the path component
2432 of the URL meets <em>any</em> of the following criteria:
2435 <li>The specified location matches exactly the path component of the URL.
2437 <li>The specified location, which ends in a forward slash, is a prefix
2438 of the path component of the URL (treated as a context root).
2440 <li>The specified location, with the addition of a trailing slash, is a
2441 prefix of the path component of the URL (also treated as a context root).
2445 In the example below, where no trailing slash is used, requests to
2446 /private1, /private1/ and /private1/file.txt will have the enclosed
2447 directives applied, but /private1other would not.
2449 <div class="example"><p><code>
2450 <Location /private1>
2454 In the example below, where a trailing slash is used, requests to
2455 /private2/ and /private2/file.txt will have the enclosed
2456 directives applied, but /private2 and /private2other would not.
2458 <div class="example"><p><code>
2459 <Location /private2<em>/</em>>
2463 <div class="note"><h3>When to use <code class="directive"><Location></code></h3>
2465 <p>Use <code class="directive"><Location></code> to apply
2466 directives to content that lives outside the filesystem. For
2467 content that lives in the filesystem, use <code class="directive"><a href="#directory"><Directory></a></code> and <code class="directive"><a href="#files"><Files></a></code>. An exception is
2468 <code><Location /></code>, which is an easy way to
2469 apply a configuration to the entire server.</p>
2472 <p>For all origin (non-proxy) requests, the URL to be matched is a
2473 URL-path of the form <code>/path/</code>. <em>No scheme, hostname,
2474 port, or query string may be included.</em> For proxy requests, the
2475 URL to be matched is of the form
2476 <code>scheme://servername/path</code>, and you must include the
2479 <p>The URL may use wildcards. In a wild-card string, <code>?</code> matches
2480 any single character, and <code>*</code> matches any sequences of
2481 characters. Neither wildcard character matches a / in the URL-path.</p>
2483 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular expressions</a>
2484 can also be used, with the addition of the <code>~</code>
2485 character. For example:</p>
2487 <div class="example"><p><code>
2488 <Location ~ "/(extra|special)/data">
2491 <p>would match URLs that contained the substring <code>/extra/data</code>
2492 or <code>/special/data</code>. The directive <code class="directive"><a href="#locationmatch"><LocationMatch></a></code> behaves
2493 identical to the regex version of <code class="directive"><Location></code>, and is preferred, for the
2494 simple reason that <code>~</code> is hard to distinguish from
2495 <code>-</code> in many fonts.</p>
2497 <p>The <code class="directive"><Location></code>
2498 functionality is especially useful when combined with the
2499 <code class="directive"><a href="#sethandler">SetHandler</a></code>
2500 directive. For example, to enable status requests, but allow them
2501 only from browsers at <code>example.com</code>, you might use:</p>
2503 <div class="example"><p><code>
2504 <Location /status><br />
2505 <span class="indent">
2506 SetHandler server-status<br />
2507 Require host example.com<br />
2512 <div class="note"><h3>Note about / (slash)</h3>
2513 <p>The slash character has special meaning depending on where in a
2514 URL it appears. People may be used to its behavior in the filesystem
2515 where multiple adjacent slashes are frequently collapsed to a single
2516 slash (<em>i.e.</em>, <code>/home///foo</code> is the same as
2517 <code>/home/foo</code>). In URL-space this is not necessarily true.
2518 The <code class="directive"><a href="#locationmatch"><LocationMatch></a></code>
2519 directive and the regex version of <code class="directive"><Location></code> require you to explicitly specify multiple
2520 slashes if that is your intention.</p>
2522 <p>For example, <code><LocationMatch ^/abc></code> would match
2523 the request URL <code>/abc</code> but not the request URL <code>
2524 //abc</code>. The (non-regex) <code class="directive"><Location></code> directive behaves similarly when used for
2525 proxy requests. But when (non-regex) <code class="directive"><Location></code> is used for non-proxy requests it will
2526 implicitly match multiple slashes with a single slash. For example,
2527 if you specify <code><Location /abc/def></code> and the
2528 request is to <code>/abc//def</code> then it will match.</p>
2533 <li><a href="../sections.html">How <Directory>, <Location>
2534 and <Files> sections work</a> for an explanation of how these
2535 different sections are combined when a request is received.</li>
2536 <li><code class="directive"><a href="#locationmatch">LocationMatch</a></code></li>
2539 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2540 <div class="directive-section"><h2><a name="LocationMatch" id="LocationMatch"><LocationMatch></a> <a name="locationmatch" id="locationmatch">Directive</a></h2>
2541 <table class="directive">
2542 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Applies the enclosed directives only to regular-expression
2543 matching URLs</td></tr>
2544 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><LocationMatch
2545 <var>regex</var>> ... </LocationMatch></code></td></tr>
2546 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2547 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2548 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2550 <p>The <code class="directive"><LocationMatch></code> directive
2551 limits the scope of the enclosed directives by URL, in an identical manner
2552 to <code class="directive"><a href="#location"><Location></a></code>. However,
2553 it takes a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expression</a>
2554 as an argument instead of a simple string. For example:</p>
2556 <div class="example"><p><code>
2557 <LocationMatch "/(extra|special)/data">
2560 <p>would match URLs that contained the substring <code>/extra/data</code>
2561 or <code>/special/data</code>.</p>
2565 <li><a href="../sections.html">How <Directory>, <Location>
2566 and <Files> sections work</a> for an explanation of how these
2567 different sections are combined when a request is received</li>
2570 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2571 <div class="directive-section"><h2><a name="LogLevel" id="LogLevel">LogLevel</a> <a name="loglevel" id="loglevel">Directive</a></h2>
2572 <table class="directive">
2573 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls the verbosity of the ErrorLog</td></tr>
2574 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LogLevel [<var>module</var>:]<var>level</var>
2575 [<var>module</var>:<var>level</var>] ...
2577 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LogLevel warn</code></td></tr>
2578 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2579 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2580 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2581 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Per-module and per-directory configuration is available in
2582 Apache HTTP Server 2.3.6 and later</td></tr>
2584 <p><code class="directive">LogLevel</code> adjusts the verbosity of the
2585 messages recorded in the error logs (see <code class="directive"><a href="#errorlog">ErrorLog</a></code> directive). The following
2586 <var>level</var>s are available, in order of decreasing
2589 <table class="bordered">
2592 <th><strong>Level</strong> </th>
2594 <th><strong>Description</strong> </th>
2596 <th><strong>Example</strong> </th>
2600 <td><code>emerg</code> </td>
2602 <td>Emergencies - system is unusable.</td>
2604 <td>"Child cannot open lock file. Exiting"</td>
2608 <td><code>alert</code> </td>
2610 <td>Action must be taken immediately.</td>
2612 <td>"getpwuid: couldn't determine user name from uid"</td>
2616 <td><code>crit</code> </td>
2618 <td>Critical Conditions.</td>
2620 <td>"socket: Failed to get a socket, exiting child"</td>
2624 <td><code>error</code> </td>
2626 <td>Error conditions.</td>
2628 <td>"Premature end of script headers"</td>
2632 <td><code>warn</code> </td>
2634 <td>Warning conditions.</td>
2636 <td>"child process 1234 did not exit, sending another
2641 <td><code>notice</code> </td>
2643 <td>Normal but significant condition.</td>
2645 <td>"httpd: caught SIGBUS, attempting to dump core in
2650 <td><code>info</code> </td>
2652 <td>Informational.</td>
2654 <td>"Server seems busy, (you may need to increase
2655 StartServers, or Min/MaxSpareServers)..."</td>
2659 <td><code>debug</code> </td>
2661 <td>Debug-level messages</td>
2663 <td>"Opening config file ..."</td>
2666 <td><code>trace1</code> </td>
2668 <td>Trace messages</td>
2670 <td>"proxy: FTP: control connection complete"</td>
2673 <td><code>trace2</code> </td>
2675 <td>Trace messages</td>
2677 <td>"proxy: CONNECT: sending the CONNECT request to the remote proxy"</td>
2680 <td><code>trace3</code> </td>
2682 <td>Trace messages</td>
2684 <td>"openssl: Handshake: start"</td>
2687 <td><code>trace4</code> </td>
2689 <td>Trace messages</td>
2691 <td>"read from buffered SSL brigade, mode 0, 17 bytes"</td>
2694 <td><code>trace5</code> </td>
2696 <td>Trace messages</td>
2698 <td>"map lookup FAILED: map=rewritemap key=keyname"</td>
2701 <td><code>trace6</code> </td>
2703 <td>Trace messages</td>
2705 <td>"cache lookup FAILED, forcing new map lookup"</td>
2708 <td><code>trace7</code> </td>
2710 <td>Trace messages, dumping large amounts of data</td>
2712 <td>"| 0000: 02 23 44 30 13 40 ac 34 df 3d bf 9a 19 49 39 15 |"</td>
2715 <td><code>trace8</code> </td>
2717 <td>Trace messages, dumping large amounts of data</td>
2719 <td>"| 0000: 02 23 44 30 13 40 ac 34 df 3d bf 9a 19 49 39 15 |"</td>
2723 <p>When a particular level is specified, messages from all
2724 other levels of higher significance will be reported as well.
2725 <em>E.g.</em>, when <code>LogLevel info</code> is specified,
2726 then messages with log levels of <code>notice</code> and
2727 <code>warn</code> will also be posted.</p>
2729 <p>Using a level of at least <code>crit</code> is
2734 <div class="example"><p><code>
2738 <div class="note"><h3>Note</h3>
2739 <p>When logging to a regular file messages of the level
2740 <code>notice</code> cannot be suppressed and thus are always
2741 logged. However, this doesn't apply when logging is done
2742 using <code>syslog</code>.</p>
2745 <p>Specifying a level without a module name will reset the level
2746 for all modules to that level. Specifying a level with a module
2747 name will set the level for that module only. It is possible to
2748 use the module source file name, the module identifier, or the
2749 module identifier with the trailing <code>_module</code> omitted
2750 as module specification. This means the following three specifications
2753 <div class="example"><p><code>
2754 LogLevel info ssl:warn<br />
2755 LogLevel info mod_ssl.c:warn<br />
2756 LogLevel info ssl_module:warn<br />
2759 <p>It is also possible to change the level per directory:</p>
2761 <div class="example"><p><code>
2763 <Directory /usr/local/apache/htdocs/app><br />
2764 LogLevel debug<br />
2769 Per directory loglevel configuration only affects messages that are
2770 logged after the request has been parsed and that are associated with
2771 the request. Log messages which are associated with the connection or
2772 the server are not affected.
2776 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2777 <div class="directive-section"><h2><a name="MaxKeepAliveRequests" id="MaxKeepAliveRequests">MaxKeepAliveRequests</a> <a name="maxkeepaliverequests" id="maxkeepaliverequests">Directive</a></h2>
2778 <table class="directive">
2779 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of requests allowed on a persistent
2780 connection</td></tr>
2781 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxKeepAliveRequests <var>number</var></code></td></tr>
2782 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxKeepAliveRequests 100</code></td></tr>
2783 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2784 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2785 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2787 <p>The <code class="directive">MaxKeepAliveRequests</code> directive
2788 limits the number of requests allowed per connection when
2789 <code class="directive"><a href="#keepalive">KeepAlive</a></code> is on. If it is
2790 set to <code>0</code>, unlimited requests will be allowed. We
2791 recommend that this setting be kept to a high value for maximum
2792 server performance.</p>
2796 <div class="example"><p><code>
2797 MaxKeepAliveRequests 500
2801 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2802 <div class="directive-section"><h2><a name="Mutex" id="Mutex">Mutex</a> <a name="mutex" id="mutex">Directive</a></h2>
2803 <table class="directive">
2804 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures mutex mechanism and lock file directory for all
2805 or specified mutexes</td></tr>
2806 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Mutex <var>mechanism</var> [default|<var>mutex-name</var>] ... [OmitPID]</code></td></tr>
2807 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Mutex default</code></td></tr>
2808 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
2809 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2810 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2811 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.4 and later</td></tr>
2813 <p>The <code class="directive">Mutex</code> directive sets the mechanism,
2814 and optionally the lock file location, that httpd and modules use
2815 to serialize access to resources. Specify <code>default</code> as
2816 the first argument to change the settings for all mutexes; specify
2817 a mutex name (see table below) as the first argument to override
2818 defaults only for that mutex.</p>
2820 <p>The <code class="directive">Mutex</code> directive is typically used in
2821 the following exceptional situations:</p>
2824 <li>change the mutex mechanism when the default mechanism selected
2825 by <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a> has a functional or performance
2828 <li>change the directory used by file-based mutexes when the
2829 default directory does not support locking</li>
2832 <div class="note"><h3>Supported modules</h3>
2833 <p>This directive only configures mutexes which have been registered
2834 with the core server using the <code>ap_mutex_register()</code> API.
2835 All modules bundled with httpd support the <code class="directive">Mutex</code>
2836 directive, but third-party modules may not. Consult the documentation
2837 of the third-party module, which must indicate the mutex name(s) which
2838 can be configured if this directive is supported.</p>
2841 <p>The following mutex <em>mechanisms</em> are available:</p>
2843 <li><code>default | yes</code>
2844 <p>This selects the default locking implementation, as determined by
2845 <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a>. The default locking implementation can
2846 be displayed by running <code class="program"><a href="../programs/httpd.html">httpd</a></code> with the
2847 <code>-V</code> option.</p></li>
2849 <li><code>none | no</code>
2850 <p>This effectively disables the mutex, and is only allowed for a
2851 mutex if the module indicates that it is a valid choice. Consult the
2852 module documentation for more information.</p></li>
2854 <li><code>posixsem</code>
2855 <p>This is a mutex variant based on a Posix semaphore.</p>
2857 <div class="warning"><h3>Warning</h3>
2858 <p>The semaphore ownership is not recovered if a thread in the process
2859 holding the mutex segfaults, resulting in a hang of the web server.</p>
2863 <li><code>sysvsem</code>
2864 <p>This is a mutex variant based on a SystemV IPC semaphore.</p>
2866 <div class="warning"><h3>Warning</h3>
2867 <p>It is possible to "leak" SysV semaphores if processes crash
2868 before the semaphore is removed.</p>
2871 <div class="warning"><h3>Security</h3>
2872 <p>The semaphore API allows for a denial of service attack by any
2873 CGIs running under the same uid as the webserver (<em>i.e.</em>,
2874 all CGIs, unless you use something like <code class="program"><a href="../programs/suexec.html">suexec</a></code>
2875 or <code>cgiwrapper</code>).</p>
2879 <li><code>sem</code>
2880 <p>This selects the "best" available semaphore implementation, choosing
2881 between Posix and SystemV IPC semaphores, in that order.</p></li>
2883 <li><code>pthread</code>
2884 <p>This is a mutex variant based on cross-process Posix thread
2887 <div class="warning"><h3>Warning</h3>
2888 <p>On most systems, if a child process terminates abnormally while
2889 holding a mutex that uses this implementation, the server will deadlock
2890 and stop responding to requests. When this occurs, the server will
2891 require a manual restart to recover.</p>
2892 <p>Solaris is a notable exception as it provides a mechanism which
2893 usually allows the mutex to be recovered after a child process
2894 terminates abnormally while holding a mutex.</p>
2895 <p>If your system implements the
2896 <code>pthread_mutexattr_setrobust_np()</code> function, you may be able
2897 to use the <code>pthread</code> option safely.</p>
2901 <li><code>fcntl:/path/to/mutex</code>
2902 <p>This is a mutex variant where a physical (lock-)file and the
2903 <code>fcntl()</code> function are used as the mutex.</p>
2905 <div class="warning"><h3>Warning</h3>
2906 <p>When multiple mutexes based on this mechanism are used within
2907 multi-threaded, multi-process environments, deadlock errors (EDEADLK)
2908 can be reported for valid mutex operations if <code>fcntl()</code>
2909 is not thread-aware, such as on Solaris.</p>
2913 <li><code>flock:/path/to/mutex</code>
2914 <p>This is similar to the <code>fcntl:/path/to/mutex</code> method
2915 with the exception that the <code>flock()</code> function is used to
2916 provide file locking.</p></li>
2918 <li><code>file:/path/to/mutex</code>
2919 <p>This selects the "best" available file locking implementation,
2920 choosing between <code>fcntl</code> and <code>flock</code>, in that
2924 <p>Most mechanisms are only available on selected platforms, where the
2925 underlying platform and <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a> support it. Mechanisms
2926 which aren't available on all platforms are <em>posixsem</em>,
2927 <em>sysvsem</em>, <em>sem</em>, <em>pthread</em>, <em>fcntl</em>,
2928 <em>flock</em>, and <em>file</em>.</p>
2930 <p>With the file-based mechanisms <em>fcntl</em> and <em>flock</em>,
2931 the path, if provided, is a directory where the lock file will be created.
2932 The default directory is httpd's run-time file directory relative to
2933 <code class="directive"><a href="#serverroot">ServerRoot</a></code>. Always use a local disk
2934 filesystem for <code>/path/to/mutex</code> and never a directory residing
2935 on a NFS- or AFS-filesystem. The basename of the file will be the mutex
2936 type, an optional instance string provided by the module, and unless the
2937 <code>OmitPID</code> keyword is specified, the process id of the httpd
2938 parent process will be appended to to make the file name unique, avoiding
2939 conflicts when multiple httpd instances share a lock file directory. For
2940 example, if the mutex name is <code>mpm-accept</code> and the lock file
2941 directory is <code>/var/httpd/locks</code>, the lock file name for the
2942 httpd instance with parent process id 12345 would be
2943 <code>/var/httpd/locks/mpm-accept.12345</code>.</p>
2945 <div class="warning"><h3>Security</h3>
2946 <p>It is best to <em>avoid</em> putting mutex files in a world-writable
2947 directory such as <code>/var/tmp</code> because someone could create
2948 a denial of service attack and prevent the server from starting by
2949 creating a lockfile with the same name as the one the server will try
2953 <p>The following table documents the names of mutexes used by httpd
2954 and bundled modules.</p>
2956 <table class="bordered"><tr class="header">
2959 <th>Protected resource</th>
2962 <td><code>mpm-accept</code></td>
2963 <td><code class="module"><a href="../mod/prefork.html">prefork</a></code> and <code class="module"><a href="../mod/worker.html">worker</a></code> MPMs</td>
2964 <td>incoming connections, to avoid the thundering herd problem;
2965 for more information, refer to the
2966 <a href="../misc/perf-tuning.html">performance tuning</a>
2970 <td><code>authdigest-client</code></td>
2971 <td><code class="module"><a href="../mod/mod_auth_digest.html">mod_auth_digest</a></code></td>
2972 <td>client list in shared memory</td>
2975 <td><code>authdigest-opaque</code></td>
2976 <td><code class="module"><a href="../mod/mod_auth_digest.html">mod_auth_digest</a></code></td>
2977 <td>counter in shared memory</td>
2980 <td><code>ldap-cache</code></td>
2981 <td><code class="module"><a href="../mod/mod_ldap.html">mod_ldap</a></code></td>
2982 <td>LDAP result cache</td>
2985 <td><code>rewrite-map</code></td>
2986 <td><code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code></td>
2987 <td>communication with external mapping programs, to avoid
2988 intermixed I/O from multiple requests</td>
2991 <td><code>ssl-cache</code></td>
2992 <td><code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code></td>
2993 <td>SSL session cache</td>
2996 <td><code>ssl-stapling</code></td>
2997 <td><code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code></td>
2998 <td>OCSP stapling response cache</td>
3001 <td><code>watchdog-callback</code></td>
3002 <td><code class="module"><a href="../mod/mod_watchdog.html">mod_watchdog</a></code></td>
3003 <td>callback function of a particular client module</td>
3007 <p>The <code>OmitPID</code> keyword suppresses the addition of the httpd
3008 parent process id from the lock file name.</p>
3010 <p>In the following example, the mutex mechanism for the MPM accept
3011 mutex will be changed from the compiled-in default to <code>fcntl</code>,
3012 with the associated lock file created in directory
3013 <code>/var/httpd/locks</code>. The mutex mechanism for all other mutexes
3014 will be changed from the compiled-in default to <code>sysvsem</code>.</p>
3016 <div class="example"><p><code>
3017 Mutex default sysvsem<br />
3018 Mutex mpm-accept fcntl:/var/httpd/locks
3022 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3023 <div class="directive-section"><h2><a name="NameVirtualHost" id="NameVirtualHost">NameVirtualHost</a> <a name="namevirtualhost" id="namevirtualhost">Directive</a></h2>
3024 <table class="directive">
3025 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Designates an IP address for name-virtual
3027 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>NameVirtualHost <var>addr</var>[:<var>port</var>]</code></td></tr>
3028 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3029 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3030 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3033 <p>Prior to 2.3.11, <code class="directive">NameVirtualHost</code> was required
3034 to instruct the server that a particular IP address and port combination
3035 was usable as a name-based virtual host. In 2.3.11 and later,
3036 any time an IP address and port combination is used in multiple virtual
3037 hosts, name-based virtual hosting is automatically enabled for that address.</p>
3039 <p>This directive currently has no effect.</p>
3043 <li><a href="../vhosts/">Virtual Hosts
3044 documentation</a></li>
3047 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3048 <div class="directive-section"><h2><a name="Options" id="Options">Options</a> <a name="options" id="options">Directive</a></h2>
3049 <table class="directive">
3050 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures what features are available in a particular
3052 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Options
3053 [+|-]<var>option</var> [[+|-]<var>option</var>] ...</code></td></tr>
3054 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Options FollowSymlinks</code></td></tr>
3055 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3056 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Options</td></tr>
3057 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3058 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3059 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>The default was changed from All to FollowSymlinks in 2.3.11</td></tr>
3061 <p>The <code class="directive">Options</code> directive controls which
3062 server features are available in a particular directory.</p>
3064 <p><var>option</var> can be set to <code>None</code>, in which
3065 case none of the extra features are enabled, or one or more of
3069 <dt><code>All</code></dt>
3071 <dd>All options except for <code>MultiViews</code>.</dd>
3073 <dt><code>ExecCGI</code></dt>
3076 Execution of CGI scripts using <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code>
3079 <dt><code>FollowSymLinks</code></dt>
3082 The server will follow symbolic links in this directory. This is
3083 the default setting.
3085 <p>Even though the server follows the symlink it does <em>not</em>
3086 change the pathname used to match against <code class="directive"><a href="#directory"><Directory></a></code> sections.</p>
3087 <p>Note also, that this option <strong>gets ignored</strong> if set
3088 inside a <code class="directive"><a href="#location"><Location></a></code>
3090 <p>Omitting this option should not be considered a security restriction,
3091 since symlink testing is subject to race conditions that make it
3095 <dt><code>Includes</code></dt>
3098 Server-side includes provided by <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
3101 <dt><code>IncludesNOEXEC</code></dt>
3105 Server-side includes are permitted, but the <code>#exec
3106 cmd</code> and <code>#exec cgi</code> are disabled. It is still
3107 possible to <code>#include virtual</code> CGI scripts from
3108 <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>ed
3111 <dt><code>Indexes</code></dt>
3114 If a URL which maps to a directory is requested, and there
3115 is no <code class="directive"><a href="../mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>
3116 (<em>e.g.</em>, <code>index.html</code>) in that directory, then
3117 <code class="module"><a href="../mod/mod_autoindex.html">mod_autoindex</a></code> will return a formatted listing
3118 of the directory.</dd>
3120 <dt><code>MultiViews</code></dt>
3123 <a href="../content-negotiation.html">Content negotiated</a>
3124 "MultiViews" are allowed using
3125 <code class="module"><a href="../mod/mod_negotiation.html">mod_negotiation</a></code>.
3126 <div class="note"><h3>Note</h3> <p>This option gets ignored if set
3127 anywhere other than <code class="directive"><a href="#directory"><Directory></a></code>, as <code class="module"><a href="../mod/mod_negotiation.html">mod_negotiation</a></code>
3128 needs real resources to compare against and evaluate from.</p></div>
3131 <dt><code>SymLinksIfOwnerMatch</code></dt>
3133 <dd>The server will only follow symbolic links for which the
3134 target file or directory is owned by the same user id as the
3137 <div class="note"><h3>Note</h3> <p>This option gets ignored if
3138 set inside a <code class="directive"><a href="#location"><Location></a></code> section.</p>
3139 <p>This option should not be considered a security restriction,
3140 since symlink testing is subject to race conditions that make it
3141 circumventable.</p></div>
3145 <p>Normally, if multiple <code class="directive">Options</code> could
3146 apply to a directory, then the most specific one is used and
3147 others are ignored; the options are not merged. (See <a href="../sections.html#mergin">how sections are merged</a>.)
3148 However if <em>all</em> the options on the
3149 <code class="directive">Options</code> directive are preceded by a
3150 <code>+</code> or <code>-</code> symbol, the options are
3151 merged. Any options preceded by a <code>+</code> are added to the
3152 options currently in force, and any options preceded by a
3153 <code>-</code> are removed from the options currently in
3156 <div class="note"><h3>Note</h3>
3157 <p>Mixing <code class="directive">Options</code> with a <code>+</code> or
3158 <code>-</code> with those without is not valid syntax, and will be
3159 rejected during server startup by the syntax check with an abort.</p>
3162 <p>For example, without any <code>+</code> and <code>-</code> symbols:</p>
3164 <div class="example"><p><code>
3165 <Directory /web/docs><br />
3166 <span class="indent">
3167 Options Indexes FollowSymLinks<br />
3169 </Directory><br />
3171 <Directory /web/docs/spec><br />
3172 <span class="indent">
3173 Options Includes<br />
3178 <p>then only <code>Includes</code> will be set for the
3179 <code>/web/docs/spec</code> directory. However if the second
3180 <code class="directive">Options</code> directive uses the <code>+</code> and
3181 <code>-</code> symbols:</p>
3183 <div class="example"><p><code>
3184 <Directory /web/docs><br />
3185 <span class="indent">
3186 Options Indexes FollowSymLinks<br />
3188 </Directory><br />
3190 <Directory /web/docs/spec><br />
3191 <span class="indent">
3192 Options +Includes -Indexes<br />
3197 <p>then the options <code>FollowSymLinks</code> and
3198 <code>Includes</code> are set for the <code>/web/docs/spec</code>
3201 <div class="note"><h3>Note</h3>
3202 <p>Using <code>-IncludesNOEXEC</code> or
3203 <code>-Includes</code> disables server-side includes completely
3204 regardless of the previous setting.</p>
3207 <p>The default in the absence of any other settings is
3208 <code>FollowSymlinks</code>.</p>
3211 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3212 <div class="directive-section"><h2><a name="Protocol" id="Protocol">Protocol</a> <a name="protocol" id="protocol">Directive</a></h2>
3213 <table class="directive">
3214 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Protocol for a listening socket</td></tr>
3215 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Protocol <var>protocol</var></code></td></tr>
3216 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3217 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3218 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3219 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache 2.1.5 and later.
3220 On Windows from Apache 2.3.3 and later.</td></tr>
3222 <p>This directive specifies the protocol used for a specific listening socket.
3223 The protocol is used to determine which module should handle a request, and
3224 to apply protocol specific optimizations with the <code class="directive">AcceptFilter</code>
3227 <p>You only need to set the protocol if you are running on non-standard ports, otherwise <code>http</code> is assumed for port 80 and <code>https</code> for port 443.</p>
3229 <p>For example, if you are running <code>https</code> on a non-standard port, specify the protocol explicitly:</p>
3231 <div class="example"><p><code>
3235 <p>You can also specify the protocol using the <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code> directive.</p>
3239 <li><code class="directive">AcceptFilter</code></li>
3240 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
3243 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3244 <div class="directive-section"><h2><a name="RLimitCPU" id="RLimitCPU">RLimitCPU</a> <a name="rlimitcpu" id="rlimitcpu">Directive</a></h2>
3245 <table class="directive">
3246 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the CPU consumption of processes launched
3247 by Apache httpd children</td></tr>
3248 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>RLimitCPU <var>seconds</var>|max [<var>seconds</var>|max]</code></td></tr>
3249 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
3250 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3251 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3252 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3253 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3255 <p>Takes 1 or 2 parameters. The first parameter sets the soft
3256 resource limit for all processes and the second parameter sets
3257 the maximum resource limit. Either parameter can be a number,
3258 or <code>max</code> to indicate to the server that the limit should
3259 be set to the maximum allowed by the operating system
3260 configuration. Raising the maximum resource limit requires that
3261 the server is running as <code>root</code>, or in the initial startup
3264 <p>This applies to processes forked off from Apache httpd children
3265 servicing requests, not the Apache httpd children themselves. This
3266 includes CGI scripts and SSI exec commands, but not any
3267 processes forked off from the Apache httpd parent such as piped
3270 <p>CPU resource limits are expressed in seconds per
3275 <li><code class="directive"><a href="#rlimitmem">RLimitMEM</a></code></li>
3276 <li><code class="directive"><a href="#rlimitnproc">RLimitNPROC</a></code></li>
3279 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3280 <div class="directive-section"><h2><a name="RLimitMEM" id="RLimitMEM">RLimitMEM</a> <a name="rlimitmem" id="rlimitmem">Directive</a></h2>
3281 <table class="directive">
3282 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the memory consumption of processes launched
3283 by Apache httpd children</td></tr>
3284 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>RLimitMEM <var>bytes</var>|max [<var>bytes</var>|max]</code></td></tr>
3285 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
3286 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3287 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3288 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3289 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3291 <p>Takes 1 or 2 parameters. The first parameter sets the soft
3292 resource limit for all processes and the second parameter sets
3293 the maximum resource limit. Either parameter can be a number,
3294 or <code>max</code> to indicate to the server that the limit should
3295 be set to the maximum allowed by the operating system
3296 configuration. Raising the maximum resource limit requires that
3297 the server is running as <code>root</code>, or in the initial startup
3300 <p>This applies to processes forked off from Apache httpd children
3301 servicing requests, not the Apache httpd children themselves. This
3302 includes CGI scripts and SSI exec commands, but not any
3303 processes forked off from the Apache httpd parent such as piped
3306 <p>Memory resource limits are expressed in bytes per
3311 <li><code class="directive"><a href="#rlimitcpu">RLimitCPU</a></code></li>
3312 <li><code class="directive"><a href="#rlimitnproc">RLimitNPROC</a></code></li>
3315 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3316 <div class="directive-section"><h2><a name="RLimitNPROC" id="RLimitNPROC">RLimitNPROC</a> <a name="rlimitnproc" id="rlimitnproc">Directive</a></h2>
3317 <table class="directive">
3318 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the number of processes that can be launched by
3319 processes launched by Apache httpd children</td></tr>
3320 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>RLimitNPROC <var>number</var>|max [<var>number</var>|max]</code></td></tr>
3321 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
3322 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3323 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3324 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3325 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3327 <p>Takes 1 or 2 parameters. The first parameter sets the soft
3328 resource limit for all processes and the second parameter sets
3329 the maximum resource limit. Either parameter can be a number,
3330 or <code>max</code> to indicate to the server that the limit
3331 should be set to the maximum allowed by the operating system
3332 configuration. Raising the maximum resource limit requires that
3333 the server is running as <code>root</code>, or in the initial startup
3336 <p>This applies to processes forked off from Apache httpd children
3337 servicing requests, not the Apache httpd children themselves. This
3338 includes CGI scripts and SSI exec commands, but not any
3339 processes forked off from the Apache httpd parent such as piped
3342 <p>Process limits control the number of processes per user.</p>
3344 <div class="note"><h3>Note</h3>
3345 <p>If CGI processes are <strong>not</strong> running
3346 under user ids other than the web server user id, this directive
3347 will limit the number of processes that the server itself can
3348 create. Evidence of this situation will be indicated by
3349 <strong><code>cannot fork</code></strong> messages in the
3350 <code>error_log</code>.</p>
3355 <li><code class="directive"><a href="#rlimitmem">RLimitMEM</a></code></li>
3356 <li><code class="directive"><a href="#rlimitcpu">RLimitCPU</a></code></li>
3359 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3360 <div class="directive-section"><h2><a name="ScriptInterpreterSource" id="ScriptInterpreterSource">ScriptInterpreterSource</a> <a name="scriptinterpretersource" id="scriptinterpretersource">Directive</a></h2>
3361 <table class="directive">
3362 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Technique for locating the interpreter for CGI
3364 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ScriptInterpreterSource Registry|Registry-Strict|Script</code></td></tr>
3365 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ScriptInterpreterSource Script</code></td></tr>
3366 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3367 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
3368 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3369 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3370 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Win32 only;
3371 option <code>Registry-Strict</code> is available in Apache HTTP Server 2.0 and
3374 <p>This directive is used to control how Apache httpd finds the
3375 interpreter used to run CGI scripts. The default setting is
3376 <code>Script</code>. This causes Apache httpd to use the interpreter pointed to
3377 by the shebang line (first line, starting with <code>#!</code>) in the
3378 script. On Win32 systems this line usually looks like:</p>
3380 <div class="example"><p><code>
3381 #!C:/Perl/bin/perl.exe
3384 <p>or, if <code>perl</code> is in the <code>PATH</code>, simply:</p>
3386 <div class="example"><p><code>
3390 <p>Setting <code>ScriptInterpreterSource Registry</code> will
3391 cause the Windows Registry tree <code>HKEY_CLASSES_ROOT</code> to be
3392 searched using the script file extension (e.g., <code>.pl</code>) as a
3393 search key. The command defined by the registry subkey
3394 <code>Shell\ExecCGI\Command</code> or, if it does not exist, by the subkey
3395 <code>Shell\Open\Command</code> is used to open the script file. If the
3396 registry keys cannot be found, Apache httpd falls back to the behavior of the
3397 <code>Script</code> option.</p>
3399 <div class="warning"><h3>Security</h3>
3400 <p>Be careful when using <code>ScriptInterpreterSource
3401 Registry</code> with <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>'ed directories, because
3402 Apache httpd will try to execute <strong>every</strong> file within this
3403 directory. The <code>Registry</code> setting may cause undesired
3404 program calls on files which are typically not executed. For
3405 example, the default open command on <code>.htm</code> files on
3406 most Windows systems will execute Microsoft Internet Explorer, so
3407 any HTTP request for an <code>.htm</code> file existing within the
3408 script directory would start the browser in the background on the
3409 server. This is a good way to crash your system within a minute or
3413 <p>The option <code>Registry-Strict</code> which is new in Apache HTTP Server
3414 2.0 does the same thing as <code>Registry</code> but uses only the
3415 subkey <code>Shell\ExecCGI\Command</code>. The
3416 <code>ExecCGI</code> key is not a common one. It must be
3417 configured manually in the windows registry and hence prevents
3418 accidental program calls on your system.</p>
3421 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3422 <div class="directive-section"><h2><a name="SeeRequestTail" id="SeeRequestTail">SeeRequestTail</a> <a name="seerequesttail" id="seerequesttail">Directive</a></h2>
3423 <table class="directive">
3424 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determine if mod_status displays the first 63 characters
3425 of a request or the last 63, assuming the request itself is greater than
3427 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SeeRequestTail On|Off</code></td></tr>
3428 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SeeRequestTail Off</code></td></tr>
3429 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3430 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3431 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3432 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache httpd 2.2.7 and later.</td></tr>
3434 <p>mod_status with <code>ExtendedStatus On</code>
3435 displays the actual request being handled.
3436 For historical purposes, only 63 characters of the request
3437 are actually stored for display purposes. This directive
3438 controls whether the 1st 63 characters are stored (the previous
3439 behavior and the default) or if the last 63 characters are. This
3440 is only applicable, of course, if the length of the request is
3441 64 characters or greater.</p>
3443 <p>If Apache httpd is handling <code>GET /disk1/storage/apache/htdocs/images/imagestore1/food/apples.jpg HTTP/1.1</code> mod_status displays as follows:
3446 <table class="bordered">
3448 <th>Off (default)</th>
3449 <td>GET /disk1/storage/apache/htdocs/images/imagestore1/food/apples</td>
3453 <td>orage/apache/htdocs/images/imagestore1/food/apples.jpg HTTP/1.1</td>
3459 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3460 <div class="directive-section"><h2><a name="ServerAdmin" id="ServerAdmin">ServerAdmin</a> <a name="serveradmin" id="serveradmin">Directive</a></h2>
3461 <table class="directive">
3462 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Email address that the server includes in error
3463 messages sent to the client</td></tr>
3464 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerAdmin <var>email-address</var>|<var>URL</var></code></td></tr>
3465 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3466 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3467 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3469 <p>The <code class="directive">ServerAdmin</code> sets the contact address
3470 that the server includes in any error messages it returns to the
3471 client. If the <code>httpd</code> doesn't recognize the supplied argument
3473 assumes, that it's an <var>email-address</var> and prepends it with
3474 <code>mailto:</code> in hyperlink targets. However, it's recommended to
3475 actually use an email address, since there are a lot of CGI scripts that
3476 make that assumption. If you want to use an URL, it should point to another
3477 server under your control. Otherwise users may not be able to contact you in
3480 <p>It may be worth setting up a dedicated address for this, e.g.</p>
3482 <div class="example"><p><code>
3483 ServerAdmin www-admin@foo.example.com
3485 <p>as users do not always mention that they are talking about the
3489 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3490 <div class="directive-section"><h2><a name="ServerAlias" id="ServerAlias">ServerAlias</a> <a name="serveralias" id="serveralias">Directive</a></h2>
3491 <table class="directive">
3492 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Alternate names for a host used when matching requests
3493 to name-virtual hosts</td></tr>
3494 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerAlias <var>hostname</var> [<var>hostname</var>] ...</code></td></tr>
3495 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>virtual host</td></tr>
3496 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3497 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3499 <p>The <code class="directive">ServerAlias</code> directive sets the
3500 alternate names for a host, for use with <a href="../vhosts/name-based.html">name-based virtual hosts</a>. The
3501 <code class="directive">ServerAlias</code> may include wildcards, if appropriate.</p>
3503 <div class="example"><p><code>
3504 <VirtualHost *:80><br />
3505 ServerName server.example.com<br />
3506 ServerAlias server server2.example.com server2<br />
3507 ServerAlias *.example.com<br />
3508 UseCanonicalName Off<br />
3510 </VirtualHost>
3515 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
3516 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
3519 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3520 <div class="directive-section"><h2><a name="ServerName" id="ServerName">ServerName</a> <a name="servername" id="servername">Directive</a></h2>
3521 <table class="directive">
3522 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Hostname and port that the server uses to identify
3524 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerName [<var>scheme</var>://]<var>fully-qualified-domain-name</var>[:<var>port</var>]</code></td></tr>
3525 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3526 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3527 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3529 <p>The <code class="directive">ServerName</code> directive sets the
3530 request scheme, hostname and
3531 port that the server uses to identify itself. This is used when
3532 creating redirection URLs.</p>
3534 <p>Additionally, <code class="directive">ServerName</code> is used (possibly
3535 in conjunction with <code class="directive">ServerAlias</code>) to uniquely
3536 identify a virtual host, when using <a href="../vhosts/name-based.html">name-based virtual hosts</a>.</p>
3538 <p>For example, if the name of the
3539 machine hosting the web server is <code>simple.example.com</code>,
3540 but the machine also has the DNS alias <code>www.example.com</code>
3541 and you wish the web server to be so identified, the following
3542 directive should be used:</p>
3544 <div class="example"><p><code>
3545 ServerName www.example.com
3548 <p>The <code class="directive">ServerName</code> directive
3549 may appear anywhere within the definition of a server. However,
3550 each appearance overrides the previous appearance (within that
3553 <p>If no <code class="directive">ServerName</code> is specified, then the
3554 server attempts to deduce the hostname by performing a reverse
3555 lookup on the IP address. If no port is specified in the
3556 <code class="directive">ServerName</code>, then the server will use the
3557 port from the incoming request. For optimal reliability and
3558 predictability, you should specify an explicit hostname and port
3559 using the <code class="directive">ServerName</code> directive.</p>
3561 <p>If you are using <a href="../vhosts/name-based.html">name-based virtual hosts</a>,
3562 the <code class="directive">ServerName</code> inside a
3563 <code class="directive"><a href="#virtualhost"><VirtualHost></a></code>
3564 section specifies what hostname must appear in the request's
3565 <code>Host:</code> header to match this virtual host.</p>
3567 <p>Sometimes, the server runs behind a device that processes SSL,
3568 such as a reverse proxy, load balancer or SSL offload
3569 appliance. When this is the case, specify the
3570 <code>https://</code> scheme and the port number to which the
3571 clients connect in the <code class="directive">ServerName</code> directive
3572 to make sure that the server generates the correct
3573 self-referential URLs.
3576 <p>See the description of the
3577 <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> and
3578 <code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code> directives for
3579 settings which determine whether self-referential URLs (e.g., by the
3580 <code class="module"><a href="../mod/mod_dir.html">mod_dir</a></code> module) will refer to the
3581 specified port, or to the port number given in the client's request.
3584 <div class="warning">
3585 <p>Failure to set <code class="directive">ServerName</code> to a name that
3586 your server can resolve to an IP address will result in a startup
3587 warning. <code>httpd</code> will then use whatever hostname it can
3588 determine, using the system's <code>hostname</code> command. This
3589 will almost never be the hostname you actually want.</p>
3590 <div class="example"><p><code>
3591 httpd: Could not reliably determine the server's fully qualified domain name, using rocinante.local for ServerName
3598 <li><a href="../dns-caveats.html">Issues Regarding DNS and
3599 Apache HTTP Server</a></li>
3600 <li><a href="../vhosts/">Apache HTTP Server virtual host
3601 documentation</a></li>
3602 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
3603 <li><code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code></li>
3604 <li><code class="directive"><a href="#serveralias">ServerAlias</a></code></li>
3607 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3608 <div class="directive-section"><h2><a name="ServerPath" id="ServerPath">ServerPath</a> <a name="serverpath" id="serverpath">Directive</a></h2>
3609 <table class="directive">
3610 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Legacy URL pathname for a name-based virtual host that
3611 is accessed by an incompatible browser</td></tr>
3612 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerPath <var>URL-path</var></code></td></tr>
3613 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>virtual host</td></tr>
3614 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3615 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3617 <p>The <code class="directive">ServerPath</code> directive sets the legacy
3618 URL pathname for a host, for use with <a href="../vhosts/">name-based virtual hosts</a>.</p>
3622 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
3625 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3626 <div class="directive-section"><h2><a name="ServerRoot" id="ServerRoot">ServerRoot</a> <a name="serverroot" id="serverroot">Directive</a></h2>
3627 <table class="directive">
3628 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Base directory for the server installation</td></tr>
3629 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerRoot <var>directory-path</var></code></td></tr>
3630 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerRoot /usr/local/apache</code></td></tr>
3631 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3632 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3633 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3635 <p>The <code class="directive">ServerRoot</code> directive sets the
3636 directory in which the server lives. Typically it will contain the
3637 subdirectories <code>conf/</code> and <code>logs/</code>. Relative
3638 paths in other configuration directives (such as <code class="directive"><a href="#include">Include</a></code> or <code class="directive"><a href="../mod/mod_so.html#loadmodule">LoadModule</a></code>, for example) are taken as
3639 relative to this directory.</p>
3641 <div class="example"><h3>Example</h3><p><code>
3642 ServerRoot /home/httpd
3648 <li><a href="../invoking.html">the <code>-d</code>
3649 option to <code>httpd</code></a></li>
3650 <li><a href="../misc/security_tips.html#serverroot">the
3651 security tips</a> for information on how to properly set
3652 permissions on the <code class="directive">ServerRoot</code></li>
3655 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3656 <div class="directive-section"><h2><a name="ServerSignature" id="ServerSignature">ServerSignature</a> <a name="serversignature" id="serversignature">Directive</a></h2>
3657 <table class="directive">
3658 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures the footer on server-generated documents</td></tr>
3659 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerSignature On|Off|EMail</code></td></tr>
3660 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerSignature Off</code></td></tr>
3661 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3662 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3663 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3664 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3666 <p>The <code class="directive">ServerSignature</code> directive allows the
3667 configuration of a trailing footer line under server-generated
3668 documents (error messages, <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> ftp directory
3669 listings, <code class="module"><a href="../mod/mod_info.html">mod_info</a></code> output, ...). The reason why you
3670 would want to enable such a footer line is that in a chain of proxies,
3671 the user often has no possibility to tell which of the chained servers
3672 actually produced a returned error message.</p>
3674 <p>The <code>Off</code>
3675 setting, which is the default, suppresses the footer line (and is
3676 therefore compatible with the behavior of Apache-1.2 and
3677 below). The <code>On</code> setting simply adds a line with the
3678 server version number and <code class="directive"><a href="#servername">ServerName</a></code> of the serving virtual host,
3679 and the <code>EMail</code> setting additionally creates a
3680 "mailto:" reference to the <code class="directive"><a href="#serveradmin">ServerAdmin</a></code> of the referenced
3683 <p>After version 2.0.44, the details of the server version number
3684 presented are controlled by the <code class="directive"><a href="#servertokens">ServerTokens</a></code> directive.</p>
3688 <li><code class="directive"><a href="#servertokens">ServerTokens</a></code></li>
3691 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3692 <div class="directive-section"><h2><a name="ServerTokens" id="ServerTokens">ServerTokens</a> <a name="servertokens" id="servertokens">Directive</a></h2>
3693 <table class="directive">
3694 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures the <code>Server</code> HTTP response
3696 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerTokens Major|Minor|Min[imal]|Prod[uctOnly]|OS|Full</code></td></tr>
3697 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerTokens Full</code></td></tr>
3698 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3699 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3700 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3702 <p>This directive controls whether <code>Server</code> response
3703 header field which is sent back to clients includes a
3704 description of the generic OS-type of the server as well as
3705 information about compiled-in modules.</p>
3708 <dt><code>ServerTokens Full</code> (or not specified)</dt>
3710 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.4.1
3711 (Unix) PHP/4.2.2 MyMod/1.2</code></dd>
3713 <dt><code>ServerTokens Prod[uctOnly]</code></dt>
3715 <dd>Server sends (<em>e.g.</em>): <code>Server:
3718 <dt><code>ServerTokens Major</code></dt>
3720 <dd>Server sends (<em>e.g.</em>): <code>Server:
3721 Apache/2</code></dd>
3723 <dt><code>ServerTokens Minor</code></dt>
3725 <dd>Server sends (<em>e.g.</em>): <code>Server:
3726 Apache/2.4</code></dd>
3728 <dt><code>ServerTokens Min[imal]</code></dt>
3730 <dd>Server sends (<em>e.g.</em>): <code>Server:
3731 Apache/2.4.1</code></dd>
3733 <dt><code>ServerTokens OS</code></dt>
3735 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.4.1
3740 <p>This setting applies to the entire server, and cannot be
3741 enabled or disabled on a virtualhost-by-virtualhost basis.</p>
3743 <p>After version 2.0.44, this directive also controls the
3744 information presented by the <code class="directive"><a href="#serversignature">ServerSignature</a></code> directive.</p>
3746 <div class="note">Setting <code class="directive">ServerTokens</code> to less than
3747 <code>minimal</code> is not recommended because it makes it more
3748 difficult to debug interoperational problems. Also note that
3749 disabling the Server: header does nothing at all to make your
3750 server more secure; the idea of "security through obscurity"
3751 is a myth and leads to a false sense of safety.</div>
3756 <li><code class="directive"><a href="#serversignature">ServerSignature</a></code></li>
3759 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3760 <div class="directive-section"><h2><a name="SetHandler" id="SetHandler">SetHandler</a> <a name="sethandler" id="sethandler">Directive</a></h2>
3761 <table class="directive">
3762 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Forces all matching files to be processed by a
3764 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetHandler <var>handler-name</var>|None</code></td></tr>
3765 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3766 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
3767 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3768 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3769 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Moved into the core in Apache httpd 2.0</td></tr>
3771 <p>When placed into an <code>.htaccess</code> file or a
3772 <code class="directive"><a href="#directory"><Directory></a></code> or
3773 <code class="directive"><a href="#location"><Location></a></code>
3774 section, this directive forces all matching files to be parsed
3775 through the <a href="../handler.html">handler</a> given by
3776 <var>handler-name</var>. For example, if you had a directory you
3777 wanted to be parsed entirely as imagemap rule files, regardless
3778 of extension, you might put the following into an
3779 <code>.htaccess</code> file in that directory:</p>
3781 <div class="example"><p><code>
3782 SetHandler imap-file
3785 <p>Another example: if you wanted to have the server display a
3786 status report whenever a URL of
3787 <code>http://servername/status</code> was called, you might put
3788 the following into <code>httpd.conf</code>:</p>
3790 <div class="example"><p><code>
3791 <Location /status><br />
3792 <span class="indent">
3793 SetHandler server-status<br />
3798 <p>You can override an earlier defined <code class="directive">SetHandler</code>
3799 directive by using the value <code>None</code>.</p>
3801 <div class="note"><h3>Note</h3>
3802 <p>Because <code class="directive">SetHandler</code> overrides default handlers,
3803 normal behaviour such as handling of URLs ending in a slash (/) as
3804 directories or index files is suppressed.</p></div>
3808 <li><code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code></li>
3811 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3812 <div class="directive-section"><h2><a name="SetInputFilter" id="SetInputFilter">SetInputFilter</a> <a name="setinputfilter" id="setinputfilter">Directive</a></h2>
3813 <table class="directive">
3814 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the filters that will process client requests and POST
3816 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetInputFilter <var>filter</var>[;<var>filter</var>...]</code></td></tr>
3817 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3818 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
3819 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3820 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3822 <p>The <code class="directive">SetInputFilter</code> directive sets the
3823 filter or filters which will process client requests and POST
3824 input when they are received by the server. This is in addition to
3825 any filters defined elsewhere, including the
3826 <code class="directive"><a href="../mod/mod_mime.html#addinputfilter">AddInputFilter</a></code>
3829 <p>If more than one filter is specified, they must be separated
3830 by semicolons in the order in which they should process the
3835 <li><a href="../filter.html">Filters</a> documentation</li>
3838 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3839 <div class="directive-section"><h2><a name="SetOutputFilter" id="SetOutputFilter">SetOutputFilter</a> <a name="setoutputfilter" id="setoutputfilter">Directive</a></h2>
3840 <table class="directive">
3841 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the filters that will process responses from the
3843 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetOutputFilter <var>filter</var>[;<var>filter</var>...]</code></td></tr>
3844 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3845 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
3846 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3847 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3849 <p>The <code class="directive">SetOutputFilter</code> directive sets the filters
3850 which will process responses from the server before they are
3851 sent to the client. This is in addition to any filters defined
3852 elsewhere, including the
3853 <code class="directive"><a href="../mod/mod_mime.html#addoutputfilter">AddOutputFilter</a></code>
3856 <p>For example, the following configuration will process all files
3857 in the <code>/www/data/</code> directory for server-side
3860 <div class="example"><p><code>
3861 <Directory /www/data/><br />
3862 <span class="indent">
3863 SetOutputFilter INCLUDES<br />
3868 <p>If more than one filter is specified, they must be separated
3869 by semicolons in the order in which they should process the
3874 <li><a href="../filter.html">Filters</a> documentation</li>
3877 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3878 <div class="directive-section"><h2><a name="TimeOut" id="TimeOut">TimeOut</a> <a name="timeout" id="timeout">Directive</a></h2>
3879 <table class="directive">
3880 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Amount of time the server will wait for
3881 certain events before failing a request</td></tr>
3882 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>TimeOut <var>seconds</var></code></td></tr>
3883 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>TimeOut 300</code></td></tr>
3884 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3885 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3886 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3888 <p>The <code class="directive">TimeOut</code> directive defines the length
3889 of time Apache httpd will wait for I/O in various circumstances:</p>
3892 <li>When reading data from the client, the length of time to
3893 wait for a TCP packet to arrive if the read buffer is
3896 <li>When writing data to the client, the length of time to wait
3897 for an acknowledgement of a packet if the send buffer is
3900 <li>In <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code>, the length of time to wait for
3901 output from a CGI script.</li>
3903 <li>In <code class="module"><a href="../mod/mod_ext_filter.html">mod_ext_filter</a></code>, the length of time to
3904 wait for output from a filtering process.</li>
3906 <li>In <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>, the default timeout value if
3907 <code class="directive"><a href="../mod/mod_proxy.html#proxytimeout">ProxyTimeout</a></code> is not
3913 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3914 <div class="directive-section"><h2><a name="TraceEnable" id="TraceEnable">TraceEnable</a> <a name="traceenable" id="traceenable">Directive</a></h2>
3915 <table class="directive">
3916 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines the behaviour on <code>TRACE</code> requests</td></tr>
3917 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>TraceEnable <var>[on|off|extended]</var></code></td></tr>
3918 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>TraceEnable on</code></td></tr>
3919 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3920 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3921 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3922 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 1.3.34, 2.0.55 and later</td></tr>
3924 <p>This directive overrides the behavior of <code>TRACE</code> for both
3925 the core server and <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>. The default
3926 <code>TraceEnable on</code> permits <code>TRACE</code> requests per
3927 RFC 2616, which disallows any request body to accompany the request.
3928 <code>TraceEnable off</code> causes the core server and
3929 <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> to return a <code>405</code> (Method not
3930 allowed) error to the client.</p>
3932 <p>Finally, for testing and diagnostic purposes only, request
3933 bodies may be allowed using the non-compliant <code>TraceEnable
3934 extended</code> directive. The core (as an origin server) will
3935 restrict the request body to 64k (plus 8k for chunk headers if
3936 <code>Transfer-Encoding: chunked</code> is used). The core will
3937 reflect the full headers and all chunk headers with the response
3938 body. As a proxy server, the request body is not restricted to 64k.</p>
3941 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3942 <div class="directive-section"><h2><a name="UnDefine" id="UnDefine">UnDefine</a> <a name="undefine" id="undefine">Directive</a></h2>
3943 <table class="directive">
3944 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Undefine the existence of a variable</td></tr>
3945 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UnDefine <var>parameter-name</var></code></td></tr>
3946 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3947 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3948 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3950 <p>Undoes the effect of a <code class="directive"><a href="#define">Define</a></code> or
3951 of passing a <code>-D</code> argument to <code class="program"><a href="../programs/httpd.html">httpd</a></code>.</p>
3952 <p>This directive can be used to toggle the use of <code class="directive"><a href="#ifdefine"><IfDefine></a></code> sections without needing to alter
3953 <code>-D</code> arguments in any startup scripts.</p>
3956 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3957 <div class="directive-section"><h2><a name="UseCanonicalName" id="UseCanonicalName">UseCanonicalName</a> <a name="usecanonicalname" id="usecanonicalname">Directive</a></h2>
3958 <table class="directive">
3959 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures how the server determines its own name and
3961 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UseCanonicalName On|Off|DNS</code></td></tr>
3962 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>UseCanonicalName Off</code></td></tr>
3963 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3964 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3965 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3967 <p>In many situations Apache httpd must construct a <em>self-referential</em>
3968 URL -- that is, a URL that refers back to the same server. With
3969 <code>UseCanonicalName On</code> Apache httpd will use the hostname and port
3970 specified in the <code class="directive"><a href="#servername">ServerName</a></code>
3971 directive to construct the canonical name for the server. This name
3972 is used in all self-referential URLs, and for the values of
3973 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> in CGIs.</p>
3975 <p>With <code>UseCanonicalName Off</code> Apache httpd will form
3976 self-referential URLs using the hostname and port supplied by
3977 the client if any are supplied (otherwise it will use the
3978 canonical name, as defined above). These values are the same
3979 that are used to implement <a href="../vhosts/name-based.html">name-based virtual hosts</a>,
3980 and are available with the same clients. The CGI variables
3981 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> will be
3982 constructed from the client supplied values as well.</p>
3984 <p>An example where this may be useful is on an intranet server
3985 where you have users connecting to the machine using short
3986 names such as <code>www</code>. You'll notice that if the users
3987 type a shortname, and a URL which is a directory, such as
3988 <code>http://www/splat</code>, <em>without the trailing
3989 slash</em> then Apache httpd will redirect them to
3990 <code>http://www.example.com/splat/</code>. If you have
3991 authentication enabled, this will cause the user to have to
3992 authenticate twice (once for <code>www</code> and once again
3993 for <code>www.example.com</code> -- see <a href="http://httpd.apache.org/docs/misc/FAQ.html#prompted-twice">the
3994 FAQ on this subject for more information</a>). But if
3995 <code class="directive">UseCanonicalName</code> is set <code>Off</code>, then
3996 Apache httpd will redirect to <code>http://www/splat/</code>.</p>
3998 <p>There is a third option, <code>UseCanonicalName DNS</code>,
3999 which is intended for use with mass IP-based virtual hosting to
4000 support ancient clients that do not provide a
4001 <code>Host:</code> header. With this option Apache httpd does a
4002 reverse DNS lookup on the server IP address that the client
4003 connected to in order to work out self-referential URLs.</p>
4005 <div class="warning"><h3>Warning</h3>
4006 <p>If CGIs make assumptions about the values of <code>SERVER_NAME</code>
4007 they may be broken by this option. The client is essentially free
4008 to give whatever value they want as a hostname. But if the CGI is
4009 only using <code>SERVER_NAME</code> to construct self-referential URLs
4010 then it should be just fine.</p>
4015 <li><code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code></li>
4016 <li><code class="directive"><a href="#servername">ServerName</a></code></li>
4017 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
4020 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4021 <div class="directive-section"><h2><a name="UseCanonicalPhysicalPort" id="UseCanonicalPhysicalPort">UseCanonicalPhysicalPort</a> <a name="usecanonicalphysicalport" id="usecanonicalphysicalport">Directive</a></h2>
4022 <table class="directive">
4023 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures how the server determines its own port</td></tr>
4024 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UseCanonicalPhysicalPort On|Off</code></td></tr>
4025 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>UseCanonicalPhysicalPort Off</code></td></tr>
4026 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
4027 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4028 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4030 <p>In many situations Apache httpd must construct a <em>self-referential</em>
4031 URL -- that is, a URL that refers back to the same server. With
4032 <code>UseCanonicalPhysicalPort On</code> Apache httpd will, when
4033 constructing the canonical port for the server to honor
4034 the <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> directive,
4035 provide the actual physical port number being used by this request
4036 as a potential port. With <code>UseCanonicalPhysicalPort Off</code>
4037 Apache httpd will not ever use the actual physical port number, instead
4038 relying on all configured information to construct a valid port number.</p>
4040 <div class="note"><h3>Note</h3>
4041 <p>The ordering of the lookup when the physical port is used is as
4044 <dt><code>UseCanonicalName On</code></dt>
4047 <li>Port provided in <code class="directive"><a href="#servername">Servername</a></code></li>
4048 <li>Physical port</li>
4049 <li>Default port</li>
4052 <dt><code>UseCanonicalName Off | DNS</code></dt>
4055 <li>Parsed port from <code>Host:</code> header</li>
4056 <li>Physical port</li>
4057 <li>Port provided in <code class="directive"><a href="#servername">Servername</a></code></li>
4058 <li>Default port</li>
4063 <p>With <code>UseCanonicalPhysicalPort Off</code>, the
4064 physical ports are removed from the ordering.</p>
4070 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
4071 <li><code class="directive"><a href="#servername">ServerName</a></code></li>
4072 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
4075 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4076 <div class="directive-section"><h2><a name="VirtualHost" id="VirtualHost"><VirtualHost></a> <a name="virtualhost" id="virtualhost">Directive</a></h2>
4077 <table class="directive">
4078 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only to a specific
4079 hostname or IP address</td></tr>
4080 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><VirtualHost
4081 <var>addr</var>[:<var>port</var>] [<var>addr</var>[:<var>port</var>]]
4082 ...> ... </VirtualHost></code></td></tr>
4083 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4084 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4085 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4087 <p><code class="directive"><VirtualHost></code> and
4088 <code></VirtualHost></code> are used to enclose a group of
4089 directives that will apply only to a particular virtual host. Any
4090 directive that is allowed in a virtual host context may be
4091 used. When the server receives a request for a document on a
4092 particular virtual host, it uses the configuration directives
4093 enclosed in the <code class="directive"><VirtualHost></code>
4094 section. <var>Addr</var> can be any of the following, optionally followed by
4095 a colon and a port number (or *):</p>
4098 <li>The IP address of the virtual host;</li>
4100 <li>A fully qualified domain name for the IP address of the
4101 virtual host (not recommended);</li>
4103 <li>The character <code>*</code>, which acts as a wildcard and matches
4104 any IP address.</li>
4106 <li>The string <code>_default_</code>, which is an alias for <code>*</code></li>
4110 <div class="example"><h3>Example</h3><p><code>
4111 <VirtualHost 10.1.2.3:80><br />
4112 <span class="indent">
4113 ServerAdmin webmaster@host.example.com<br />
4114 DocumentRoot /www/docs/host.example.com<br />
4115 ServerName host.example.com<br />
4116 ErrorLog logs/host.example.com-error_log<br />
4117 TransferLog logs/host.example.com-access_log<br />
4119 </VirtualHost>
4123 <p>IPv6 addresses must be specified in square brackets because
4124 the optional port number could not be determined otherwise. An
4125 IPv6 example is shown below:</p>
4127 <div class="example"><p><code>
4128 <VirtualHost [2001:db8::a00:20ff:fea7:ccea]:80><br />
4129 <span class="indent">
4130 ServerAdmin webmaster@host.example.com<br />
4131 DocumentRoot /www/docs/host.example.com<br />
4132 ServerName host.example.com<br />
4133 ErrorLog logs/host.example.com-error_log<br />
4134 TransferLog logs/host.example.com-access_log<br />
4136 </VirtualHost>
4139 <p>Each Virtual Host must correspond to a different IP address,
4140 different port number or a different host name for the server,
4141 in the former case the server machine must be configured to
4142 accept IP packets for multiple addresses. (If the machine does
4143 not have multiple network interfaces, then this can be
4144 accomplished with the <code>ifconfig alias</code> command -- if
4145 your OS supports it).</p>
4147 <div class="note"><h3>Note</h3>
4148 <p>The use of <code class="directive"><VirtualHost></code> does
4149 <strong>not</strong> affect what addresses Apache httpd listens on. You
4150 may need to ensure that Apache httpd is listening on the correct addresses
4151 using <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code>.</p>
4154 <p>A <code class="directive"><a href="#servername">ServerName</a></code> should be
4155 specified inside each <code class="directive"><VirtualHost></code> block. If it is absent, the
4156 <code class="directive"><a href="#servername">ServerName</a></code> from the "main"
4157 server configuration will be inherited.</p>
4159 <p>When a request is received, the server first maps it to the best matching
4160 <code class="directive"><VirtualHost></code> based on the local
4161 IP address and port combination only. Non-wildcards have a higher
4162 precedence. If no match based on IP and port occurs at all, the
4163 "main" server configuration is used.</p>
4165 <p>If multiple virtual hosts contain the best matching IP address and port,
4166 the server selects from these virtual hosts the best match based on the
4167 requested hostname. If no matching name-based virtual host is found,
4168 then the first listed virtual host that matched the IP address will be
4169 used. As a consequence, the first listed virtual host for a given IP address
4170 and port combination is default virtual host for that IP and port
4173 <div class="warning"><h3>Security</h3>
4174 <p>See the <a href="../misc/security_tips.html">security tips</a>
4175 document for details on why your security could be compromised if the
4176 directory where log files are stored is writable by anyone other
4177 than the user that starts the server.</p>
4182 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
4183 <li><a href="../dns-caveats.html">Issues Regarding DNS and
4184 Apache HTTP Server</a></li>
4185 <li><a href="../bind.html">Setting
4186 which addresses and ports Apache HTTP Server uses</a></li>
4187 <li><a href="../sections.html">How <Directory>, <Location>
4188 and <Files> sections work</a> for an explanation of how these
4189 different sections are combined when a request is received</li>
4193 <div class="bottomlang">
4194 <p><span>Available Languages: </span><a href="../de/mod/core.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
4195 <a href="../en/mod/core.html" title="English"> en </a> |
4196 <a href="../es/mod/core.html" hreflang="es" rel="alternate" title="Español"> es </a> |
4197 <a href="../fr/mod/core.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
4198 <a href="../ja/mod/core.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
4199 <a href="../tr/mod/core.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
4200 </div><div id="footer">
4201 <p class="apache">Copyright 2011 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
4202 <p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div>
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