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10 <title>core - Apache HTTP Server Version 2.5</title>
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20 <p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/quickreference.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
21 <p class="apache">Apache HTTP Server Version 2.5</p>
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25 <a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.5</a> > <a href="./">Modules</a></div>
26 <div id="page-content">
27 <div id="preamble"><h1>Apache Core Features</h1>
29 <p><span>Available Languages: </span><a href="../de/mod/core.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
30 <a href="../en/mod/core.html" title="English"> en </a> |
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36 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Core Apache HTTP Server features that are always
38 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>Core</td></tr></table>
40 <div id="quickview"><h3 class="directives">Directives</h3>
42 <li><img alt="" src="../images/down.gif" /> <a href="#acceptfilter">AcceptFilter</a></li>
43 <li><img alt="" src="../images/down.gif" /> <a href="#acceptpathinfo">AcceptPathInfo</a></li>
44 <li><img alt="" src="../images/down.gif" /> <a href="#accessfilename">AccessFileName</a></li>
45 <li><img alt="" src="../images/down.gif" /> <a href="#adddefaultcharset">AddDefaultCharset</a></li>
46 <li><img alt="" src="../images/down.gif" /> <a href="#allowencodedslashes">AllowEncodedSlashes</a></li>
47 <li><img alt="" src="../images/down.gif" /> <a href="#allowoverride">AllowOverride</a></li>
48 <li><img alt="" src="../images/down.gif" /> <a href="#allowoverridelist">AllowOverrideList</a></li>
49 <li><img alt="" src="../images/down.gif" /> <a href="#asyncfilter">AsyncFilter</a></li>
50 <li><img alt="" src="../images/down.gif" /> <a href="#cgimapextension">CGIMapExtension</a></li>
51 <li><img alt="" src="../images/down.gif" /> <a href="#cgipassauth">CGIPassAuth</a></li>
52 <li><img alt="" src="../images/down.gif" /> <a href="#cgivar">CGIVar</a></li>
53 <li><img alt="" src="../images/down.gif" /> <a href="#contentdigest">ContentDigest</a></li>
54 <li><img alt="" src="../images/down.gif" /> <a href="#defaultruntimedir">DefaultRuntimeDir</a></li>
55 <li><img alt="" src="../images/down.gif" /> <a href="#defaulttype">DefaultType</a></li>
56 <li><img alt="" src="../images/down.gif" /> <a href="#define">Define</a></li>
57 <li><img alt="" src="../images/down.gif" /> <a href="#directory"><Directory></a></li>
58 <li><img alt="" src="../images/down.gif" /> <a href="#directorymatch"><DirectoryMatch></a></li>
59 <li><img alt="" src="../images/down.gif" /> <a href="#documentroot">DocumentRoot</a></li>
60 <li><img alt="" src="../images/down.gif" /> <a href="#else"><Else></a></li>
61 <li><img alt="" src="../images/down.gif" /> <a href="#elseif"><ElseIf></a></li>
62 <li><img alt="" src="../images/down.gif" /> <a href="#enablemmap">EnableMMAP</a></li>
63 <li><img alt="" src="../images/down.gif" /> <a href="#enablesendfile">EnableSendfile</a></li>
64 <li><img alt="" src="../images/down.gif" /> <a href="#error">Error</a></li>
65 <li><img alt="" src="../images/down.gif" /> <a href="#errordocument">ErrorDocument</a></li>
66 <li><img alt="" src="../images/down.gif" /> <a href="#errorlog">ErrorLog</a></li>
67 <li><img alt="" src="../images/down.gif" /> <a href="#errorlogformat">ErrorLogFormat</a></li>
68 <li><img alt="" src="../images/down.gif" /> <a href="#extendedstatus">ExtendedStatus</a></li>
69 <li><img alt="" src="../images/down.gif" /> <a href="#fileetag">FileETag</a></li>
70 <li><img alt="" src="../images/down.gif" /> <a href="#files"><Files></a></li>
71 <li><img alt="" src="../images/down.gif" /> <a href="#filesmatch"><FilesMatch></a></li>
72 <li><img alt="" src="../images/down.gif" /> <a href="#forcetype">ForceType</a></li>
73 <li><img alt="" src="../images/down.gif" /> <a href="#gprofdir">GprofDir</a></li>
74 <li><img alt="" src="../images/down.gif" /> <a href="#hostnamelookups">HostnameLookups</a></li>
75 <li><img alt="" src="../images/down.gif" /> <a href="#httpprotocoloptions">HttpProtocolOptions</a></li>
76 <li><img alt="" src="../images/down.gif" /> <a href="#if"><If></a></li>
77 <li><img alt="" src="../images/down.gif" /> <a href="#ifdefine"><IfDefine></a></li>
78 <li><img alt="" src="../images/down.gif" /> <a href="#iffile"><IfFile></a></li>
79 <li><img alt="" src="../images/down.gif" /> <a href="#ifmodule"><IfModule></a></li>
80 <li><img alt="" src="../images/down.gif" /> <a href="#include">Include</a></li>
81 <li><img alt="" src="../images/down.gif" /> <a href="#includeoptional">IncludeOptional</a></li>
82 <li><img alt="" src="../images/down.gif" /> <a href="#keepalive">KeepAlive</a></li>
83 <li><img alt="" src="../images/down.gif" /> <a href="#keepalivetimeout">KeepAliveTimeout</a></li>
84 <li><img alt="" src="../images/down.gif" /> <a href="#limit"><Limit></a></li>
85 <li><img alt="" src="../images/down.gif" /> <a href="#limitexcept"><LimitExcept></a></li>
86 <li><img alt="" src="../images/down.gif" /> <a href="#limitinternalrecursion">LimitInternalRecursion</a></li>
87 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestbody">LimitRequestBody</a></li>
88 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestfields">LimitRequestFields</a></li>
89 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestfieldsize">LimitRequestFieldSize</a></li>
90 <li><img alt="" src="../images/down.gif" /> <a href="#limitrequestline">LimitRequestLine</a></li>
91 <li><img alt="" src="../images/down.gif" /> <a href="#limitxmlrequestbody">LimitXMLRequestBody</a></li>
92 <li><img alt="" src="../images/down.gif" /> <a href="#location"><Location></a></li>
93 <li><img alt="" src="../images/down.gif" /> <a href="#locationmatch"><LocationMatch></a></li>
94 <li><img alt="" src="../images/down.gif" /> <a href="#loglevel">LogLevel</a></li>
95 <li><img alt="" src="../images/down.gif" /> <a href="#logleveloverride">LogLevelOverride</a></li>
96 <li><img alt="" src="../images/down.gif" /> <a href="#maxkeepaliverequests">MaxKeepAliveRequests</a></li>
97 <li><img alt="" src="../images/down.gif" /> <a href="#maxrangeoverlaps">MaxRangeOverlaps</a></li>
98 <li><img alt="" src="../images/down.gif" /> <a href="#maxrangereversals">MaxRangeReversals</a></li>
99 <li><img alt="" src="../images/down.gif" /> <a href="#maxranges">MaxRanges</a></li>
100 <li><img alt="" src="../images/down.gif" /> <a href="#mergetrailers">MergeTrailers</a></li>
101 <li><img alt="" src="../images/down.gif" /> <a href="#mutex">Mutex</a></li>
102 <li><img alt="" src="../images/down.gif" /> <a href="#namevirtualhost">NameVirtualHost</a></li>
103 <li><img alt="" src="../images/down.gif" /> <a href="#options">Options</a></li>
104 <li><img alt="" src="../images/down.gif" /> <a href="#protocol">Protocol</a></li>
105 <li><img alt="" src="../images/down.gif" /> <a href="#protocols">Protocols</a></li>
106 <li><img alt="" src="../images/down.gif" /> <a href="#protocolshonororder">ProtocolsHonorOrder</a></li>
107 <li><img alt="" src="../images/down.gif" /> <a href="#qualifyredirecturl">QualifyRedirectURL</a></li>
108 <li><img alt="" src="../images/down.gif" /> <a href="#registerhttpmethod">RegisterHttpMethod</a></li>
109 <li><img alt="" src="../images/down.gif" /> <a href="#rlimitcpu">RLimitCPU</a></li>
110 <li><img alt="" src="../images/down.gif" /> <a href="#rlimitmem">RLimitMEM</a></li>
111 <li><img alt="" src="../images/down.gif" /> <a href="#rlimitnproc">RLimitNPROC</a></li>
112 <li><img alt="" src="../images/down.gif" /> <a href="#scriptinterpretersource">ScriptInterpreterSource</a></li>
113 <li><img alt="" src="../images/down.gif" /> <a href="#seerequesttail">SeeRequestTail</a></li>
114 <li><img alt="" src="../images/down.gif" /> <a href="#serveradmin">ServerAdmin</a></li>
115 <li><img alt="" src="../images/down.gif" /> <a href="#serveralias">ServerAlias</a></li>
116 <li><img alt="" src="../images/down.gif" /> <a href="#servername">ServerName</a></li>
117 <li><img alt="" src="../images/down.gif" /> <a href="#serverpath">ServerPath</a></li>
118 <li><img alt="" src="../images/down.gif" /> <a href="#serverroot">ServerRoot</a></li>
119 <li><img alt="" src="../images/down.gif" /> <a href="#serversignature">ServerSignature</a></li>
120 <li><img alt="" src="../images/down.gif" /> <a href="#servertokens">ServerTokens</a></li>
121 <li><img alt="" src="../images/down.gif" /> <a href="#sethandler">SetHandler</a></li>
122 <li><img alt="" src="../images/down.gif" /> <a href="#setinputfilter">SetInputFilter</a></li>
123 <li><img alt="" src="../images/down.gif" /> <a href="#setoutputfilter">SetOutputFilter</a></li>
124 <li><img alt="" src="../images/down.gif" /> <a href="#timeout">TimeOut</a></li>
125 <li><img alt="" src="../images/down.gif" /> <a href="#traceenable">TraceEnable</a></li>
126 <li><img alt="" src="../images/down.gif" /> <a href="#undefine">UnDefine</a></li>
127 <li><img alt="" src="../images/down.gif" /> <a href="#usecanonicalname">UseCanonicalName</a></li>
128 <li><img alt="" src="../images/down.gif" /> <a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></li>
129 <li><img alt="" src="../images/down.gif" /> <a href="#virtualhost"><VirtualHost></a></li>
130 <li><img alt="" src="../images/down.gif" /> <a href="#warning">Warning</a></li>
132 <h3>Bugfix checklist</h3><ul class="seealso"><li><a href="https://www.apache.org/dist/httpd/CHANGES_2.4">httpd changelog</a></li><li><a href="https://bz.apache.org/bugzilla/buglist.cgi?bug_status=__open__&list_id=144532&product=Apache%20httpd-2&query_format=specific&order=changeddate%20DESC%2Cpriority%2Cbug_severity&component=core">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&component=core">Report a bug</a></li></ul><h3>See also</h3>
134 <li><a href="#comments_section">Comments</a></li></ul></div>
136 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
137 <div class="directive-section"><h2><a name="AcceptFilter" id="AcceptFilter">AcceptFilter</a> <a name="acceptfilter" id="acceptfilter">Directive</a></h2>
138 <table class="directive">
139 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures optimizations for a Protocol's Listener Sockets</td></tr>
140 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AcceptFilter <var>protocol</var> <var>accept_filter</var></code></td></tr>
141 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
142 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
143 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
145 <p>This directive enables operating system specific optimizations for a
146 listening socket by the <code class="directive">Protocol</code> type.
147 The basic premise is for the kernel to not send a socket to the server
148 process until either data is received or an entire HTTP Request is buffered.
149 Only <a href="http://www.freebsd.org/cgi/man.cgi?query=accept_filter&sektion=9">
150 FreeBSD's Accept Filters</a>, Linux's more primitive
151 <code>TCP_DEFER_ACCEPT</code>, and Windows' optimized AcceptEx()
152 are currently supported.</p>
154 <p>Using <code>none</code> for an argument will disable any accept filters
155 for that protocol. This is useful for protocols that require a server
156 send data first, such as <code>ftp:</code> or <code>nntp</code>:</p>
157 <pre class="prettyprint lang-config">AcceptFilter nntp none</pre>
160 <p>The default protocol names are <code>https</code> for port 443
161 and <code>http</code> for all other ports. To specify that another
162 protocol is being used with a listening port, add the <var>protocol</var>
163 argument to the <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code>
166 <p>The default values on FreeBSD are:</p>
167 <pre class="prettyprint lang-config">AcceptFilter http httpready
168 AcceptFilter https dataready</pre>
171 <p>The <code>httpready</code> accept filter buffers entire HTTP requests at
172 the kernel level. Once an entire request is received, the kernel then
173 sends it to the server. See the
174 <a href="http://www.freebsd.org/cgi/man.cgi?query=accf_http&sektion=9">
175 accf_http(9)</a> man page for more details. Since HTTPS requests are
176 encrypted, only the <a href="http://www.freebsd.org/cgi/man.cgi?query=accf_data&sektion=9">
177 accf_data(9)</a> filter is used.</p>
179 <p>The default values on Linux are:</p>
180 <pre class="prettyprint lang-config">AcceptFilter http data
181 AcceptFilter https data</pre>
184 <p>Linux's <code>TCP_DEFER_ACCEPT</code> does not support buffering http
185 requests. Any value besides <code>none</code> will enable
186 <code>TCP_DEFER_ACCEPT</code> on that listener. For more details
188 <a href="http://man7.org/linux/man-pages/man7/tcp.7.html">
189 tcp(7)</a> man page.</p>
191 <p>The default values on Windows are:</p>
192 <pre class="prettyprint lang-config">AcceptFilter http connect
193 AcceptFilter https connect</pre>
196 <p>Window's mpm_winnt interprets the AcceptFilter to toggle the AcceptEx()
197 API, and does not support http protocol buffering. <code>connect</code>
198 will use the AcceptEx() API, also retrieve the network endpoint
199 addresses, but like <code>none</code> the <code>connect</code> option
200 does not wait for the initial data transmission.</p>
202 <p>On Windows, <code>none</code> uses accept() rather than AcceptEx()
203 and will not recycle sockets between connections. This is useful for
204 network adapters with broken driver support, as well as some virtual
205 network providers such as vpn drivers, or spam, virus or spyware
208 <div class="warning">
209 <h3>The <code>data</code> AcceptFilter (Windows)</h3>
211 <p>For versions 2.4.23 and prior, the Windows <code>data</code> accept
212 filter waited until data had been transmitted and the initial data
213 buffer and network endpoint addresses had been retrieved from the
214 single AcceptEx() invocation. This implementation was subject to a
215 denial of service attack and has been disabled.</p>
217 <p>Current releases of httpd default to the <code>connect</code> filter
218 on Windows, and will fall back to <code>connect</code> if
219 <code>data</code> is specified. Users of prior releases are encouraged
220 to add an explicit setting of <code>connect</code> for their
221 AcceptFilter, as shown above.</p>
227 <li><code class="directive"><a href="#protocol">Protocol</a></code></li>
230 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
231 <div class="directive-section"><h2><a name="AcceptPathInfo" id="AcceptPathInfo">AcceptPathInfo</a> <a name="acceptpathinfo" id="acceptpathinfo">Directive</a></h2>
232 <table class="directive">
233 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Resources accept trailing pathname information</td></tr>
234 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AcceptPathInfo On|Off|Default</code></td></tr>
235 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AcceptPathInfo Default</code></td></tr>
236 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
237 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
238 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
239 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
242 <p>This directive controls whether requests that contain trailing
243 pathname information that follows an actual filename (or
244 non-existent file in an existing directory) will be accepted or
245 rejected. The trailing pathname information can be made
246 available to scripts in the <code>PATH_INFO</code> environment
249 <p>For example, assume the location <code>/test/</code> points to
250 a directory that contains only the single file
251 <code>here.html</code>. Then requests for
252 <code>/test/here.html/more</code> and
253 <code>/test/nothere.html/more</code> both collect
254 <code>/more</code> as <code>PATH_INFO</code>.</p>
256 <p>The three possible arguments for the
257 <code class="directive">AcceptPathInfo</code> directive are:</p>
259 <dt><code>Off</code></dt><dd>A request will only be accepted if it
260 maps to a literal path that exists. Therefore a request with
261 trailing pathname information after the true filename such as
262 <code>/test/here.html/more</code> in the above example will return
263 a 404 NOT FOUND error.</dd>
265 <dt><code>On</code></dt><dd>A request will be accepted if a
266 leading path component maps to a file that exists. The above
267 example <code>/test/here.html/more</code> will be accepted if
268 <code>/test/here.html</code> maps to a valid file.</dd>
270 <dt><code>Default</code></dt><dd>The treatment of requests with
271 trailing pathname information is determined by the <a href="../handler.html">handler</a> responsible for the request.
272 The core handler for normal files defaults to rejecting
273 <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
274 <code>PATH_INFO</code> by default.</dd>
277 <p>The primary purpose of the <code>AcceptPathInfo</code>
278 directive is to allow you to override the handler's choice of
279 accepting or rejecting <code>PATH_INFO</code>. This override is required,
280 for example, when you use a <a href="../filter.html">filter</a>, such
281 as <a href="mod_include.html">INCLUDES</a>, to generate content
282 based on <code>PATH_INFO</code>. The core handler would usually reject
283 the request, so you can use the following configuration to enable
286 <pre class="prettyprint lang-config"><Files "mypaths.shtml">
288 SetOutputFilter INCLUDES
295 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
296 <div class="directive-section"><h2><a name="AccessFileName" id="AccessFileName">AccessFileName</a> <a name="accessfilename" id="accessfilename">Directive</a></h2>
297 <table class="directive">
298 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Name of the distributed configuration file</td></tr>
299 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AccessFileName <var>filename</var> [<var>filename</var>] ...</code></td></tr>
300 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AccessFileName .htaccess</code></td></tr>
301 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
302 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
303 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
305 <p>While processing a request, the server looks for
306 the first existing configuration file from this list of names in
307 every directory of the path to the document, if distributed
308 configuration files are <a href="#allowoverride">enabled for that
309 directory</a>. For example:</p>
311 <pre class="prettyprint lang-config">AccessFileName .acl</pre>
314 <p>Before returning the document
315 <code>/usr/local/web/index.html</code>, the server will read
316 <code>/.acl</code>, <code>/usr/.acl</code>,
317 <code>/usr/local/.acl</code> and <code>/usr/local/web/.acl</code>
318 for directives unless they have been disabled with:</p>
320 <pre class="prettyprint lang-config"><Directory "/">
322 </Directory></pre>
327 <li><code class="directive"><a href="#allowoverride">AllowOverride</a></code></li>
328 <li><a href="../configuring.html">Configuration Files</a></li>
329 <li><a href="../howto/htaccess.html">.htaccess Files</a></li>
332 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
333 <div class="directive-section"><h2><a name="AddDefaultCharset" id="AddDefaultCharset">AddDefaultCharset</a> <a name="adddefaultcharset" id="adddefaultcharset">Directive</a></h2>
334 <table class="directive">
335 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Default charset parameter to be added when a response
336 content-type is <code>text/plain</code> or <code>text/html</code></td></tr>
337 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AddDefaultCharset On|Off|<var>charset</var></code></td></tr>
338 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AddDefaultCharset Off</code></td></tr>
339 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
340 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
341 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
342 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
344 <p>This directive specifies a default value for the media type
345 charset parameter (the name of a character encoding) to be added
346 to a response if and only if the response's content-type is either
347 <code>text/plain</code> or <code>text/html</code>. This should override
348 any charset specified in the body of the response via a <code>META</code>
349 element, though the exact behavior is often dependent on the user's client
350 configuration. A setting of <code>AddDefaultCharset Off</code>
351 disables this functionality. <code>AddDefaultCharset On</code> enables
352 a default charset of <code>iso-8859-1</code>. Any other value is assumed
353 to be the <var>charset</var> to be used, which should be one of the
354 <a href="http://www.iana.org/assignments/character-sets">IANA registered
355 charset values</a> for use in Internet media types (MIME types).
358 <pre class="prettyprint lang-config">AddDefaultCharset utf-8</pre>
361 <p><code class="directive">AddDefaultCharset</code> should only be used when all
362 of the text resources to which it applies are known to be in that
363 character encoding and it is too inconvenient to label their charset
364 individually. One such example is to add the charset parameter
365 to resources containing generated content, such as legacy CGI
366 scripts, that might be vulnerable to cross-site scripting attacks
367 due to user-provided data being included in the output. Note, however,
368 that a better solution is to just fix (or delete) those scripts, since
369 setting a default charset does not protect users that have enabled
370 the "auto-detect character encoding" feature on their browser.</p>
374 <li><code class="directive"><a href="../mod/mod_mime.html#addcharset">AddCharset</a></code></li>
377 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
378 <div class="directive-section"><h2><a name="AllowEncodedSlashes" id="AllowEncodedSlashes">AllowEncodedSlashes</a> <a name="allowencodedslashes" id="allowencodedslashes">Directive</a></h2>
379 <table class="directive">
380 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines whether encoded path separators in URLs are allowed to
381 be passed through</td></tr>
382 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AllowEncodedSlashes On|Off|NoDecode</code></td></tr>
383 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AllowEncodedSlashes Off</code></td></tr>
384 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
385 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
386 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
387 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>
388 NoDecode option available in 2.3.12 and later.</td></tr>
390 <p>The <code class="directive">AllowEncodedSlashes</code> directive allows URLs
391 which contain encoded path separators (<code>%2F</code> for <code>/</code>
392 and additionally <code>%5C</code> for <code>\</code> on accordant systems)
393 to be used in the path info.</p>
395 <p>With the default value, <code>Off</code>, such URLs are refused
396 with a 404 (Not found) error.</p>
398 <p>With the value <code>On</code>, such URLs are accepted, and encoded
399 slashes are decoded like all other encoded characters.</p>
401 <p>With the value <code>NoDecode</code>, such URLs are accepted, but
402 encoded slashes are not decoded but left in their encoded state.</p>
404 <p>Turning <code class="directive">AllowEncodedSlashes</code> <code>On</code> is
405 mostly useful when used in conjunction with <code>PATH_INFO</code>.</p>
407 <div class="note"><h3>Note</h3>
408 <p>If encoded slashes are needed in path info, use of <code>NoDecode</code> is
409 strongly recommended as a security measure. Allowing slashes
410 to be decoded could potentially allow unsafe paths.</p>
415 <li><code class="directive"><a href="#acceptpathinfo">AcceptPathInfo</a></code></li>
418 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
419 <div class="directive-section"><h2><a name="AllowOverride" id="AllowOverride">AllowOverride</a> <a name="allowoverride" id="allowoverride">Directive</a></h2>
420 <table class="directive">
421 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Types of directives that are allowed in
422 <code>.htaccess</code> files</td></tr>
423 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AllowOverride All|None|<var>directive-type</var>
424 [<var>directive-type</var>] ...</code></td></tr>
425 <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>
426 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory</td></tr>
427 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
428 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
430 <p>When the server finds an <code>.htaccess</code> file (as
431 specified by <code class="directive"><a href="#accessfilename">AccessFileName</a></code>),
432 it needs to know which directives declared in that file can override
433 earlier configuration directives.</p>
435 <div class="note"><h3>Only available in <Directory> sections</h3>
436 <code class="directive">AllowOverride</code> is valid only in
437 <code class="directive"><a href="#directory"><Directory></a></code>
438 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
439 <code class="directive"><a href="#files"><Files></a></code> sections.
442 <p>When this directive is set to <code>None</code> and <code class="directive"><a href="#allowoverridelist">AllowOverrideList</a></code> is set to
443 <code>None</code>, <a href="#accessfilename">.htaccess</a> files are
444 completely ignored. In this case, the server will not even attempt
445 to read <code>.htaccess</code> files in the filesystem.</p>
447 <p>When this directive is set to <code>All</code>, then any
448 directive which has the .htaccess <a href="directive-dict.html#Context">Context</a> is allowed in
449 <code>.htaccess</code> files.</p>
451 <p>The <var>directive-type</var> can be one of the following
452 groupings of directives.</p>
459 Allow use of the authorization directives (<code class="directive"><a href="../mod/mod_authz_dbm.html#authdbmgroupfile">AuthDBMGroupFile</a></code>,
460 <code class="directive"><a href="../mod/mod_authn_dbm.html#authdbmuserfile">AuthDBMUserFile</a></code>,
461 <code class="directive"><a href="../mod/mod_authz_groupfile.html#authgroupfile">AuthGroupFile</a></code>,
462 <code class="directive"><a href="../mod/mod_authn_core.html#authname">AuthName</a></code>,
463 <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>
468 Allow use of the directives controlling document types
469 (<code class="directive"><a href="#errordocument">ErrorDocument</a></code>,
470 <code class="directive"><a href="#forcetype">ForceType</a></code>,
471 <code class="directive"><a href="../mod/mod_negotiation.html#languagepriority">LanguagePriority</a></code>,
472 <code class="directive"><a href="#sethandler">SetHandler</a></code>,
473 <code class="directive"><a href="#setinputfilter">SetInputFilter</a></code>,
474 <code class="directive"><a href="#setoutputfilter">SetOutputFilter</a></code>, and
475 <code class="module"><a href="../mod/mod_mime.html">mod_mime</a></code> Add* and Remove* directives),
476 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>),
477 <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>),
478 <code class="module"><a href="../mod/mod_alias.html">mod_alias</a></code> directives (<code class="directive"><a href="../mod/mod_alias.html#redirect">Redirect</a></code>, <code class="directive"><a href="../mod/mod_alias.html#redirecttemp">RedirectTemp</a></code>, <code class="directive"><a href="../mod/mod_alias.html#redirectpermanent">RedirectPermanent</a></code>, <code class="directive"><a href="../mod/mod_alias.html#redirectmatch">RedirectMatch</a></code>), and
479 <code class="directive"><a href="../mod/mod_actions.html#action">Action</a></code> from
480 <code class="module"><a href="../mod/mod_actions.html">mod_actions</a></code>.
486 Allow use of the directives controlling directory indexing
487 (<code class="directive"><a href="../mod/mod_autoindex.html#adddescription">AddDescription</a></code>,
488 <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>,
489 <code class="directive"><a href="../mod/mod_autoindex.html#addiconbytype">AddIconByType</a></code>,
490 <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_dir.html#fallbackresource">FallbackResource</a></code>, <a href="mod_autoindex.html#indexoptions.fancyindexing"><code>FancyIndexing</code></a>, <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>,
496 Allow use of the directives controlling host access (<code class="directive"><a href="../mod/mod_access_compat.html#allow">Allow</a></code>, <code class="directive"><a href="../mod/mod_access_compat.html#deny">Deny</a></code> and <code class="directive"><a href="../mod/mod_access_compat.html#order">Order</a></code>).</dd>
501 <dt>Nonfatal=[Override|Unknown|All]</dt>
504 Allow use of AllowOverride option to treat invalid (unrecognized
505 or disallowed) directives in
506 .htaccess as nonfatal. Instead of causing an Internal Server
507 Error, disallowed or unrecognised directives will be ignored
508 and a warning logged:
510 <li><strong>Nonfatal=Override</strong> treats directives
511 forbidden by AllowOverride as nonfatal.</li>
512 <li><strong>Nonfatal=Unknown</strong> treats unknown directives
513 as nonfatal. This covers typos and directives implemented
514 by a module that's not present.</li>
515 <li><strong>Nonfatal=All</strong> treats both the above as nonfatal.</li>
517 <p>Note that a syntax error in a valid directive will still cause
518 an Internal Server Error.</p>
519 <div class="warning"><h3>Security</h3>
520 Nonfatal errors may have security implications for .htaccess users.
521 For example, if AllowOverride disallows AuthConfig, users'
522 configuration designed to restrict access to a site will be disabled.
526 <dt>Options[=<var>Option</var>,...]</dt>
529 Allow use of the directives controlling specific directory
530 features (<code class="directive"><a href="#options">Options</a></code> and
531 <code class="directive"><a href="../mod/mod_include.html#xbithack">XBitHack</a></code>).
532 An equal sign may be given followed by a comma-separated list, without
533 spaces, of options that may be set using the <code class="directive"><a href="#options">Options</a></code> command.
535 <div class="note"><h3>Implicit disabling of Options</h3>
536 <p>Even though the list of options that may be used in .htaccess files
537 can be limited with this directive, as long as any <code class="directive"><a href="#options">Options</a></code> directive is allowed any
538 other inherited option can be disabled by using the non-relative
539 syntax. In other words, this mechanism cannot force a specific option
540 to remain <em>set</em> while allowing any others to be set.
543 <div class="example"><p><code>
544 AllowOverride Options=Indexes,MultiViews
551 <pre class="prettyprint lang-config">AllowOverride AuthConfig Indexes</pre>
554 <p>In the example above, all directives that are neither in the group
555 <code>AuthConfig</code> nor <code>Indexes</code> cause an internal
558 <div class="note"><p>For security and performance reasons, do not set
559 <code>AllowOverride</code> to anything other than <code>None</code>
560 in your <code><Directory "/"></code> block. Instead, find (or
561 create) the <code><Directory></code> block that refers to the
562 directory where you're actually planning to place a
563 <code>.htaccess</code> file.</p>
568 <li><code class="directive"><a href="#accessfilename">AccessFileName</a></code></li>
569 <li><code class="directive"><a href="#allowoverridelist">AllowOverrideList</a></code></li>
570 <li><a href="../configuring.html">Configuration Files</a></li>
571 <li><a href="../howto/htaccess.html">.htaccess Files</a></li>
574 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
575 <div class="directive-section"><h2><a name="AllowOverrideList" id="AllowOverrideList">AllowOverrideList</a> <a name="allowoverridelist" id="allowoverridelist">Directive</a></h2>
576 <table class="directive">
577 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Individual directives that are allowed in
578 <code>.htaccess</code> files</td></tr>
579 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AllowOverrideList None|<var>directive</var>
580 [<var>directive-type</var>] ...</code></td></tr>
581 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AllowOverrideList None</code></td></tr>
582 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory</td></tr>
583 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
584 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
586 <p>When the server finds an <code>.htaccess</code> file (as
587 specified by <code class="directive"><a href="#accessfilename">AccessFileName</a></code>),
588 it needs to know which directives declared in that file can override
589 earlier configuration directives.</p>
591 <div class="note"><h3>Only available in <Directory> sections</h3>
592 <code class="directive">AllowOverrideList</code> is valid only in
593 <code class="directive"><a href="#directory"><Directory></a></code>
594 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
595 <code class="directive"><a href="#files"><Files></a></code> sections.
598 <p>When this directive is set to <code>None</code> and <code class="directive"><a href="#allowoverride">AllowOverride</a></code> is set to <code>None</code>,
599 then <a href="#accessfilename">.htaccess</a> files are completely
600 ignored. In this case, the server will not even attempt to read
601 <code>.htaccess</code> files in the filesystem.</p>
605 <pre class="prettyprint lang-config">AllowOverride None
606 AllowOverrideList Redirect RedirectMatch</pre>
609 <p>In the example above, only the <code>Redirect</code> and
610 <code>RedirectMatch</code> directives are allowed. All others will
611 cause an Internal Server Error.</p>
615 <pre class="prettyprint lang-config">AllowOverride AuthConfig
616 AllowOverrideList CookieTracking CookieName</pre>
619 <p>In the example above, <code class="directive"><a href="#allowoverride">AllowOverride
620 </a></code> grants permission to the <code>AuthConfig</code>
621 directive grouping and <code class="directive">AllowOverrideList</code> grants
622 permission to only two directives from the <code>FileInfo</code> directive
623 grouping. All others will cause an Internal Server Error.</p>
627 <li><code class="directive"><a href="#accessfilename">AccessFileName</a></code></li>
628 <li><code class="directive"><a href="#allowoverride">AllowOverride</a></code></li>
629 <li><a href="../configuring.html">Configuration Files</a></li>
630 <li><a href="../howto/htaccess.html">.htaccess Files</a></li>
633 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
634 <div class="directive-section"><h2><a name="AsyncFilter" id="AsyncFilter">AsyncFilter</a> <a name="asyncfilter" id="asyncfilter">Directive</a></h2>
635 <table class="directive">
636 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Set the minimum filter type eligible for asynchronous handling</td></tr>
637 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>AsyncFilter request|connection|network</code></td></tr>
638 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>AsyncFilter request</code></td></tr>
639 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
640 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
641 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
642 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Only available from Apache 2.5.0 and later.</td></tr>
644 <p>This directive controls the minimum filter levels that are eligible
645 for asynchronous handling. This may be necessary to support legacy external
646 filters that did not handle meta buckets correctly.</p>
648 <p>If set to "network", asynchronous handling will be limited to the network
649 filter only. If set to "connection", all connection and network filters
650 will be eligible for asynchronous handling, including <code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code>.
651 If set to "request", all filters will be eligible for asynchronous handling.</p>
654 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
655 <div class="directive-section"><h2><a name="CGIMapExtension" id="CGIMapExtension">CGIMapExtension</a> <a name="cgimapextension" id="cgimapextension">Directive</a></h2>
656 <table class="directive">
657 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Technique for locating the interpreter for CGI
659 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CGIMapExtension <var>cgi-path</var> <var>.extension</var></code></td></tr>
660 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
661 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
662 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
663 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
664 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>NetWare only</td></tr>
666 <p>This directive is used to control how Apache httpd finds the
667 interpreter used to run CGI scripts. For example, setting
668 <code>CGIMapExtension sys:\foo.nlm .foo</code> will
669 cause all CGI script files with a <code>.foo</code> extension to
670 be passed to the FOO interpreter.</p>
673 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
674 <div class="directive-section"><h2><a name="CGIPassAuth" id="CGIPassAuth">CGIPassAuth</a> <a name="cgipassauth" id="cgipassauth">Directive</a></h2>
675 <table class="directive">
676 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables passing HTTP authorization headers to scripts as CGI
678 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CGIPassAuth On|Off</code></td></tr>
679 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>CGIPassAuth Off</code></td></tr>
680 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
681 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig</td></tr>
682 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
683 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
684 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.4.13 and later</td></tr>
686 <p><code class="directive">CGIPassAuth</code> allows scripts access to HTTP
687 authorization headers such as <code>Authorization</code>, which is
688 required for scripts that implement HTTP Basic authentication.
689 Normally these HTTP headers are hidden from scripts. This is to disallow
690 scripts from seeing user ids and passwords used to access the server when
691 HTTP Basic authentication is enabled in the web server. This directive
692 should be used when scripts are allowed to implement HTTP Basic
695 <p>This directive can be used instead of the compile-time setting
696 <code>SECURITY_HOLE_PASS_AUTHORIZATION</code> which has been available
697 in previous versions of Apache HTTP Server.</p>
699 <p>The setting is respected by any modules which use
700 <code>ap_add_common_vars()</code>, such as <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code>,
701 <code class="module"><a href="../mod/mod_cgid.html">mod_cgid</a></code>, <code class="module"><a href="../mod/mod_proxy_fcgi.html">mod_proxy_fcgi</a></code>,
702 <code class="module"><a href="../mod/mod_proxy_scgi.html">mod_proxy_scgi</a></code>, and so on. Notably, it affects
703 modules which don't handle the request in the usual sense but
704 still use this API; examples of this are <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
705 and <code class="module"><a href="../mod/mod_ext_filter.html">mod_ext_filter</a></code>. Third-party modules that don't
706 use <code>ap_add_common_vars()</code> may choose to respect the setting
710 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
711 <div class="directive-section"><h2><a name="CGIVar" id="CGIVar">CGIVar</a> <a name="cgivar" id="cgivar">Directive</a></h2>
712 <table class="directive">
713 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls how some CGI variables are set</td></tr>
714 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CGIVar <var>variable</var> <var>rule</var></code></td></tr>
715 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
716 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
717 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
718 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
719 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.4.21 and later</td></tr>
721 <p>This directive controls how some CGI variables are set.</p>
723 <p><strong>REQUEST_URI</strong> rules:</p>
725 <dt><code>original-uri</code> (default)</dt>
726 <dd>The value is taken from the original request line, and will not
727 reflect internal redirects or subrequests which change the requested
729 <dt><code>current-uri</code></dt>
730 <dd>The value reflects the resource currently being processed,
731 which may be different than the original request from the client
732 due to internal redirects or subrequests.</dd>
736 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
737 <div class="directive-section"><h2><a name="ContentDigest" id="ContentDigest">ContentDigest</a> <a name="contentdigest" id="contentdigest">Directive</a></h2>
738 <table class="directive">
739 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables the generation of <code>Content-MD5</code> HTTP Response
741 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ContentDigest On|Off</code></td></tr>
742 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ContentDigest Off</code></td></tr>
743 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
744 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Options</td></tr>
745 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
746 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
748 <p>This directive enables the generation of
749 <code>Content-MD5</code> headers as defined in RFC1864
750 respectively RFC2616.</p>
752 <p>MD5 is an algorithm for computing a "message digest"
753 (sometimes called "fingerprint") of arbitrary-length data, with
754 a high degree of confidence that any alterations in the data
755 will be reflected in alterations in the message digest.</p>
757 <p>The <code>Content-MD5</code> header provides an end-to-end
758 message integrity check (MIC) of the entity-body. A proxy or
759 client may check this header for detecting accidental
760 modification of the entity-body in transit. Example header:</p>
762 <div class="example"><p><code>
763 Content-MD5: AuLb7Dp1rqtRtxz2m9kRpA==
766 <p>Note that this can cause performance problems on your server
767 since the message digest is computed on every request (the
768 values are not cached).</p>
770 <p><code>Content-MD5</code> is only sent for documents served
771 by the <code class="module"><a href="../mod/core.html">core</a></code>, and not by any module. For example,
772 SSI documents, output from CGI scripts, and byte range responses
773 do not have this header.</p>
776 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
777 <div class="directive-section"><h2><a name="DefaultRuntimeDir" id="DefaultRuntimeDir">DefaultRuntimeDir</a> <a name="defaultruntimedir" id="defaultruntimedir">Directive</a></h2>
778 <table class="directive">
779 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Base directory for the server run-time files</td></tr>
780 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DefaultRuntimeDir <var>directory-path</var></code></td></tr>
781 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DefaultRuntimeDir DEFAULT_REL_RUNTIMEDIR (logs/)</code></td></tr>
782 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
783 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
784 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
785 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache 2.4.2 and later</td></tr>
787 <p>The <code class="directive">DefaultRuntimeDir</code> directive sets the
788 directory in which the server will create various run-time files
789 (shared memory, locks, etc.). If set as a relative path, the full path
790 will be relative to <code class="directive">ServerRoot</code>.</p>
792 <p><strong>Example</strong></p>
793 <pre class="prettyprint lang-config">DefaultRuntimeDir scratch/</pre>
796 <p>The default location of <code class="directive">DefaultRuntimeDir</code> may be
797 modified by changing the <code>DEFAULT_REL_RUNTIMEDIR</code> #define
800 <p>Note: <code class="directive">ServerRoot</code> should be specified before this
801 directive is used. Otherwise, the default value of <code class="directive">ServerRoot</code>
802 would be used to set the base directory.</p>
807 <li><a href="../misc/security_tips.html#serverroot">the
808 security tips</a> for information on how to properly set
809 permissions on the <code class="directive">ServerRoot</code></li>
812 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
813 <div class="directive-section"><h2><a name="DefaultType" id="DefaultType">DefaultType</a> <a name="defaulttype" id="defaulttype">Directive</a></h2>
814 <table class="directive">
815 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>This directive has no effect other than to emit warnings
816 if the value is not <code>none</code>. In prior versions, DefaultType
817 would specify a default media type to assign to response content for
818 which no other media type configuration could be found.
820 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DefaultType <var>media-type|none</var></code></td></tr>
821 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DefaultType none</code></td></tr>
822 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
823 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
824 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
825 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
826 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>All choices except <code>none</code> are DISABLED for 2.3.x and later.
829 <p>This directive has been disabled. For backwards compatibility
830 of configuration files, it may be specified with the value
831 <code>none</code>, meaning no default media type. For example:</p>
833 <pre class="prettyprint lang-config">DefaultType None</pre>
836 <p><code>DefaultType None</code> is only available in
837 httpd-2.2.7 and later.</p>
839 <p>Use the mime.types configuration file and the
840 <code class="directive"><a href="../mod/mod_mime.html#addtype">AddType</a></code> to configure media
841 type assignments via file extensions, or the
842 <code class="directive"><a href="#forcetype">ForceType</a></code> directive to configure
843 the media type for specific resources. Otherwise, the server will
844 send the response without a Content-Type header field and the
845 recipient may attempt to guess the media type.</p>
848 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
849 <div class="directive-section"><h2><a name="Define" id="Define">Define</a> <a name="define" id="define">Directive</a></h2>
850 <table class="directive">
851 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Define a variable</td></tr>
852 <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>
853 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
854 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
855 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
857 <p>In its one parameter form, <code class="directive">Define</code> is equivalent
858 to passing the <code>-D</code> argument to <code class="program"><a href="../programs/httpd.html">httpd</a></code>. It
859 can be used to toggle the use of
860 <code class="directive"><a href="#ifdefine"><IfDefine></a></code> sections
861 without needing to alter <code>-D</code> arguments in any startup
864 <p>In addition to that, if the second parameter is given, a config variable
865 is set to this value. The variable can be used in the configuration using
866 the <code>${VAR}</code> syntax. The variable is always globally defined
867 and not limited to the scope of the surrounding config section.</p>
869 <pre class="prettyprint lang-config"><IfDefine TEST>
870 Define servername test.example.com
872 <IfDefine !TEST>
873 Define servername www.example.com
877 DocumentRoot "/var/www/${servername}/htdocs"</pre>
880 <p>Variable names may not contain colon ":" characters, to avoid clashes
881 with <code class="directive"><a href="../mod/mod_rewrite.html#rewritemap">RewriteMap</a></code>'s syntax.</p>
883 <p>While this directive is supported in virtual host context,
884 the changes it makes are visible to any later configuration
885 directives, beyond any enclosing virtual host</p>
888 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
889 <div class="directive-section"><h2><a name="Directory" id="Directory"><Directory></a> <a name="directory" id="directory">Directive</a></h2>
890 <table class="directive">
891 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enclose a group of directives that apply only to the
892 named file-system directory, sub-directories, and their contents.</td></tr>
893 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Directory <var>directory-path</var>>
894 ... </Directory></code></td></tr>
895 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
896 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
897 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
899 <p><code class="directive"><Directory></code> and
900 <code></Directory></code> are used to enclose a group of
901 directives that will apply only to the named directory,
902 sub-directories of that directory, and the files within the respective
903 directories. Any directive that is allowed
904 in a directory context may be used. <var>Directory-path</var> is
905 either the full path to a directory, or a wild-card string using
906 Unix shell-style matching. In a wild-card string, <code>?</code> matches
907 any single character, and <code>*</code> matches any sequences of
908 characters. You may also use <code>[]</code> character ranges. None
909 of the wildcards match a `/' character, so <code><Directory
910 "/*/public_html"></code> will not match
911 <code>/home/user/public_html</code>, but <code><Directory
912 "/home/*/public_html"></code> will match. Example:</p>
914 <pre class="prettyprint lang-config"><Directory "/usr/local/httpd/htdocs">
915 Options Indexes FollowSymLinks
916 </Directory></pre>
919 <p>Directory paths <em>may</em> be quoted, if you like, however, it
920 <em>must</em> be quoted if the path contains spaces. This is because a
921 space would otherwise indicate the end of an argument.</p>
924 <p>Be careful with the <var>directory-path</var> arguments:
925 They have to literally match the filesystem path which Apache httpd uses
926 to access the files. Directives applied to a particular
927 <code><Directory></code> will not apply to files accessed from
928 that same directory via a different path, such as via different symbolic
932 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular
933 expressions</a> can also be used, with the addition of the
934 <code>~</code> character. For example:</p>
936 <pre class="prettyprint lang-config"><Directory ~ "^/www/[0-9]{3}">
938 </Directory></pre>
941 <p>would match directories in <code>/www/</code> that consisted of
944 <p>If multiple (non-regular expression) <code class="directive"><Directory></code> sections
945 match the directory (or one of its parents) containing a document,
946 then the directives are applied in the order of shortest match
947 first, interspersed with the directives from the <a href="#accessfilename">.htaccess</a> files. For example,
950 <pre class="prettyprint lang-config"><Directory "/">
954 <Directory "/home">
955 AllowOverride FileInfo
956 </Directory></pre>
959 <p>for access to the document <code>/home/web/dir/doc.html</code>
963 <li>Apply directive <code>AllowOverride None</code>
964 (disabling <code>.htaccess</code> files).</li>
966 <li>Apply directive <code>AllowOverride FileInfo</code> (for
967 directory <code>/home</code>).</li>
969 <li>Apply any <code>FileInfo</code> directives in
970 <code>/home/.htaccess</code>, <code>/home/web/.htaccess</code> and
971 <code>/home/web/dir/.htaccess</code> in that order.</li>
974 <p>Regular expressions are not considered until after all of the
975 normal sections have been applied. Then all of the regular
976 expressions are tested in the order they appeared in the
977 configuration file. For example, with</p>
979 <pre class="prettyprint lang-config"><Directory ~ "abc$">
980 # ... directives here ...
981 </Directory></pre>
984 <p>the regular expression section won't be considered until after
985 all normal <code class="directive"><Directory></code>s and
986 <code>.htaccess</code> files have been applied. Then the regular
987 expression will match on <code>/home/abc/public_html/abc</code> and
988 the corresponding <code class="directive"><Directory></code> will
991 <p><strong>Note that the default access for
992 <code><Directory "/"></code> is to permit all access.
993 This means that Apache httpd will serve any file mapped from an URL. It is
994 recommended that you change this with a block such
997 <pre class="prettyprint lang-config"><Directory "/">
999 </Directory></pre>
1002 <p><strong>and then override this for directories you
1003 <em>want</em> accessible. See the <a href="../misc/security_tips.html">Security Tips</a> page for more
1004 details.</strong></p>
1006 <p>The directory sections occur in the <code>httpd.conf</code> file.
1007 <code class="directive"><Directory></code> directives
1008 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>
1012 <li><a href="../sections.html">How <Directory>,
1013 <Location> and <Files> sections work</a> for an
1014 explanation of how these different sections are combined when a
1015 request is received</li>
1018 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1019 <div class="directive-section"><h2><a name="DirectoryMatch" id="DirectoryMatch"><DirectoryMatch></a> <a name="directorymatch" id="directorymatch">Directive</a></h2>
1020 <table class="directive">
1021 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enclose directives that apply to
1022 the contents of file-system directories matching a regular expression.</td></tr>
1023 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><DirectoryMatch <var>regex</var>>
1024 ... </DirectoryMatch></code></td></tr>
1025 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1026 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1027 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1029 <p><code class="directive"><DirectoryMatch></code> and
1030 <code></DirectoryMatch></code> are used to enclose a group
1031 of directives which will apply only to the named directory (and the files within),
1032 the same as <code class="directive"><a href="#directory"><Directory></a></code>.
1033 However, it takes as an argument a
1034 <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expression</a>. For example:</p>
1036 <pre class="prettyprint lang-config"><DirectoryMatch "^/www/(.+/)?[0-9]{3}/">
1038 </DirectoryMatch></pre>
1041 <p>matches directories in <code>/www/</code> (or any subdirectory thereof)
1042 that consist of three numbers.</p>
1044 <div class="note"><h3>Compatability</h3>
1045 Prior to 2.3.9, this directive implicitly applied to sub-directories
1046 (like <code class="directive"><a href="#directory"><Directory></a></code>) and
1047 could not match the end of line symbol ($). In 2.3.9 and later,
1048 only directories that match the expression are affected by the enclosed
1052 <div class="note"><h3>Trailing Slash</h3>
1053 This directive applies to requests for directories that may or may
1054 not end in a trailing slash, so expressions that are anchored to the
1055 end of line ($) must be written with care.
1058 <p>From 2.4.8 onwards, named groups and backreferences are captured and
1059 written to the environment with the corresponding name prefixed with
1060 "MATCH_" and in upper case. This allows elements of paths to be referenced
1061 from within <a href="../expr.html">expressions</a> and modules like
1062 <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>. In order to prevent confusion, numbered
1063 (unnamed) backreferences are ignored. Use named groups instead.</p>
1065 <pre class="prettyprint lang-config"><DirectoryMatch "^/var/www/combined/(?<sitename>[^/]+)">
1066 Require ldap-group cn=%{env:MATCH_SITENAME},ou=combined,o=Example
1067 </DirectoryMatch></pre>
1072 <li><code class="directive"><a href="#directory"><Directory></a></code> for
1073 a description of how regular expressions are mixed in with normal
1074 <code class="directive"><Directory></code>s</li>
1075 <li><a href="../sections.html">How <Directory>, <Location> and
1076 <Files> sections work</a> for an explanation of how these different
1077 sections are combined when a request is received</li>
1080 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1081 <div class="directive-section"><h2><a name="DocumentRoot" id="DocumentRoot">DocumentRoot</a> <a name="documentroot" id="documentroot">Directive</a></h2>
1082 <table class="directive">
1083 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Directory that forms the main document tree visible
1084 from the web</td></tr>
1085 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>DocumentRoot <var>directory-path</var></code></td></tr>
1086 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>DocumentRoot "/usr/local/apache/htdocs"</code></td></tr>
1087 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1088 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1089 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1091 <p>This directive sets the directory from which <code class="program"><a href="../programs/httpd.html">httpd</a></code>
1092 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
1093 path from the requested URL to the document root to make the
1094 path to the document. Example:</p>
1096 <pre class="prettyprint lang-config">DocumentRoot "/usr/web"</pre>
1099 <p>then an access to
1100 <code>http://my.example.com/index.html</code> refers to
1101 <code>/usr/web/index.html</code>. If the <var>directory-path</var> is
1102 not absolute then it is assumed to be relative to the <code class="directive"><a href="#serverroot">ServerRoot</a></code>.</p>
1104 <p>The <code class="directive">DocumentRoot</code> should be specified without
1105 a trailing slash.</p>
1109 <li><a href="../urlmapping.html#documentroot">Mapping URLs to Filesystem
1113 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1114 <div class="directive-section"><h2><a name="Else" id="Else"><Else></a> <a name="else" id="else">Directive</a></h2>
1115 <table class="directive">
1116 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if the condition of a
1117 previous <code class="directive"><a href="#if"><If></a></code> or
1118 <code class="directive"><a href="#elseif"><ElseIf></a></code> section is not
1119 satisfied by a request at runtime</td></tr>
1120 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Else> ... </Else></code></td></tr>
1121 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1122 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1123 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1124 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1126 <p>The <code class="directive"><Else></code> applies the enclosed
1127 directives if and only if the most recent
1128 <code class="directive"><If></code> or
1129 <code class="directive"><ElseIf></code> section
1130 in the same scope has not been applied.
1131 For example: In </p>
1133 <pre class="prettyprint lang-config"><If "-z req('Host')">
1141 <p> The <code class="directive"><If></code> would match HTTP/1.0
1142 requests without a <var>Host:</var> header and the
1143 <code class="directive"><Else></code> would match requests
1144 with a <var>Host:</var> header.</p>
1149 <li><code class="directive"><a href="#if"><If></a></code></li>
1150 <li><code class="directive"><a href="#elseif"><ElseIf></a></code></li>
1151 <li><a href="../sections.html">How <Directory>, <Location>,
1152 <Files> sections work</a> for an explanation of how these
1153 different sections are combined when a request is received.
1154 <code class="directive"><If></code>,
1155 <code class="directive"><ElseIf></code>, and
1156 <code class="directive"><Else></code> are applied last.</li>
1159 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1160 <div class="directive-section"><h2><a name="ElseIf" id="ElseIf"><ElseIf></a> <a name="elseif" id="elseif">Directive</a></h2>
1161 <table class="directive">
1162 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if a condition is satisfied
1163 by a request at runtime while the condition of a previous
1164 <code class="directive"><a href="#if"><If></a></code> or
1165 <code class="directive"><ElseIf></code> section is not
1167 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><ElseIf <var>expression</var>> ... </ElseIf></code></td></tr>
1168 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1169 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1170 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1171 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1173 <p>The <code class="directive"><ElseIf></code> applies the enclosed
1174 directives if and only if both the given condition evaluates to true and
1175 the most recent <code class="directive"><If></code> or
1176 <code class="directive"><ElseIf></code> section in the same scope has
1177 not been applied. For example: In </p>
1179 <pre class="prettyprint lang-config"><If "-R '10.1.0.0/16'">
1182 <ElseIf "-R '10.0.0.0/8'">
1190 <p>The <code class="directive"><ElseIf></code> would match if
1191 the remote address of a request belongs to the subnet 10.0.0.0/8 but
1192 not to the subnet 10.1.0.0/16.</p>
1197 <li><a href="../expr.html">Expressions in Apache HTTP Server</a>,
1198 for a complete reference and more examples.</li>
1199 <li><code class="directive"><a href="#if"><If></a></code></li>
1200 <li><code class="directive"><a href="#else"><Else></a></code></li>
1201 <li><a href="../sections.html">How <Directory>, <Location>,
1202 <Files> sections work</a> for an explanation of how these
1203 different sections are combined when a request is received.
1204 <code class="directive"><If></code>,
1205 <code class="directive"><ElseIf></code>, and
1206 <code class="directive"><Else></code> are applied last.</li>
1209 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1210 <div class="directive-section"><h2><a name="EnableMMAP" id="EnableMMAP">EnableMMAP</a> <a name="enablemmap" id="enablemmap">Directive</a></h2>
1211 <table class="directive">
1212 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Use memory-mapping to read files during delivery</td></tr>
1213 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>EnableMMAP On|Off</code></td></tr>
1214 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>EnableMMAP On</code></td></tr>
1215 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1216 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1217 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1218 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1220 <p>This directive controls whether the <code class="program"><a href="../programs/httpd.html">httpd</a></code> may use
1221 memory-mapping if it needs to read the contents of a file during
1222 delivery. By default, when the handling of a request requires
1223 access to the data within a file -- for example, when delivering a
1224 server-parsed file using <code class="module"><a href="../mod/mod_include.html">mod_include</a></code> -- Apache httpd
1225 memory-maps the file if the OS supports it.</p>
1227 <p>This memory-mapping sometimes yields a performance improvement.
1228 But in some environments, it is better to disable the memory-mapping
1229 to prevent operational problems:</p>
1232 <li>On some multiprocessor systems, memory-mapping can reduce the
1233 performance of the <code class="program"><a href="../programs/httpd.html">httpd</a></code>.</li>
1234 <li>Deleting or truncating a file while <code class="program"><a href="../programs/httpd.html">httpd</a></code>
1235 has it memory-mapped can cause <code class="program"><a href="../programs/httpd.html">httpd</a></code> to
1236 crash with a segmentation fault.
1240 <p>For server configurations that are vulnerable to these problems,
1241 you should disable memory-mapping of delivered files by specifying:</p>
1243 <pre class="prettyprint lang-config">EnableMMAP Off</pre>
1246 <p>For NFS mounted files, this feature may be disabled explicitly for
1247 the offending files by specifying:</p>
1249 <pre class="prettyprint lang-config"><Directory "/path-to-nfs-files">
1251 </Directory></pre>
1255 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1256 <div class="directive-section"><h2><a name="EnableSendfile" id="EnableSendfile">EnableSendfile</a> <a name="enablesendfile" id="enablesendfile">Directive</a></h2>
1257 <table class="directive">
1258 <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>
1259 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>EnableSendfile On|Off</code></td></tr>
1260 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>EnableSendfile Off</code></td></tr>
1261 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1262 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1263 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1264 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1265 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Default changed to Off in
1266 version 2.3.9.</td></tr>
1268 <p>This directive controls whether <code class="program"><a href="../programs/httpd.html">httpd</a></code> may use the
1269 sendfile support from the kernel to transmit file contents to the client.
1270 By default, when the handling of a request requires no access
1271 to the data within a file -- for example, when delivering a
1272 static file -- Apache httpd uses sendfile to deliver the file contents
1273 without ever reading the file if the OS supports it.</p>
1275 <p>This sendfile mechanism avoids separate read and send operations,
1276 and buffer allocations. But on some platforms or within some
1277 filesystems, it is better to disable this feature to avoid
1278 operational problems:</p>
1281 <li>Some platforms may have broken sendfile support that the build
1282 system did not detect, especially if the binaries were built on
1283 another box and moved to such a machine with broken sendfile
1285 <li>On Linux the use of sendfile triggers TCP-checksum
1286 offloading bugs on certain networking cards when using IPv6.</li>
1287 <li>On Linux on Itanium, <code>sendfile</code> may be unable to handle
1288 files over 2GB in size.</li>
1289 <li>With a network-mounted <code class="directive"><a href="#documentroot">DocumentRoot</a></code> (e.g., NFS, SMB, CIFS, FUSE),
1290 the kernel may be unable to serve the network file through
1294 <p>For server configurations that are not vulnerable to these problems,
1295 you may enable this feature by specifying:</p>
1297 <pre class="prettyprint lang-config">EnableSendfile On</pre>
1300 <p>For network mounted files, this feature may be disabled explicitly
1301 for the offending files by specifying:</p>
1303 <pre class="prettyprint lang-config"><Directory "/path-to-nfs-files">
1305 </Directory></pre>
1307 <p>Please note that the per-directory and .htaccess configuration
1308 of <code class="directive">EnableSendfile</code> is not supported by
1309 <code class="module"><a href="../mod/mod_cache_disk.html">mod_cache_disk</a></code>.
1310 Only global definition of <code class="directive">EnableSendfile</code>
1311 is taken into account by the module.
1315 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1316 <div class="directive-section"><h2><a name="Error" id="Error">Error</a> <a name="error" id="error">Directive</a></h2>
1317 <table class="directive">
1318 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Abort configuration parsing with a custom error message</td></tr>
1319 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Error <var>message</var></code></td></tr>
1320 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1321 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1322 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1323 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.3.9 and later</td></tr>
1325 <p>If an error can be detected within the configuration, this
1326 directive can be used to generate a custom error message, and halt
1327 configuration parsing. The typical use is for reporting required
1328 modules which are missing from the configuration.</p>
1330 <pre class="prettyprint lang-config"># Example
1331 # ensure that mod_include is loaded
1332 <IfModule !include_module>
1333 Error "mod_include is required by mod_foo. Load it with LoadModule."
1336 # ensure that exactly one of SSL,NOSSL is defined
1337 <IfDefine SSL>
1338 <IfDefine NOSSL>
1339 Error "Both SSL and NOSSL are defined. Define only one of them."
1342 <IfDefine !SSL>
1343 <IfDefine !NOSSL>
1344 Error "Either SSL or NOSSL must be defined."
1346 </IfDefine></pre>
1351 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1352 <div class="directive-section"><h2><a name="ErrorDocument" id="ErrorDocument">ErrorDocument</a> <a name="errordocument" id="errordocument">Directive</a></h2>
1353 <table class="directive">
1354 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>What the server will return to the client
1355 in case of an error</td></tr>
1356 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ErrorDocument <var>error-code</var> <var>document</var></code></td></tr>
1357 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1358 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1359 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1360 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1362 <p>In the event of a problem or error, Apache httpd can be configured
1363 to do one of four things,</p>
1366 <li>output a simple hardcoded error message</li>
1368 <li>output a customized message</li>
1370 <li>internally redirect to a local <var>URL-path</var> to handle the
1373 <li>redirect to an external <var>URL</var> to handle the
1377 <p>The first option is the default, while options 2-4 are
1378 configured using the <code class="directive">ErrorDocument</code>
1379 directive, which is followed by the HTTP response code and a URL
1380 or a message. Apache httpd will sometimes offer additional information
1381 regarding the problem/error.</p>
1383 <p>From 2.4.13, <a href="../expr.html">expression syntax</a> can be
1384 used inside the directive to produce dynamic strings and URLs.</p>
1386 <p>URLs can begin with a slash (/) for local web-paths (relative
1387 to the <code class="directive"><a href="#documentroot">DocumentRoot</a></code>), or be a
1388 full URL which the client can resolve. Alternatively, a message
1389 can be provided to be displayed by the browser. Note that deciding
1390 whether the parameter is an URL, a path or a message is performed
1391 before any expression is parsed. Examples:</p>
1393 <pre class="prettyprint lang-config">ErrorDocument 500 http://example.com/cgi-bin/server-error.cgi
1394 ErrorDocument 404 /errors/bad_urls.php
1395 ErrorDocument 401 /subscription_info.html
1396 ErrorDocument 403 "Sorry, can't allow you access today"
1397 ErrorDocument 403 Forbidden!
1398 ErrorDocument 403 /errors/forbidden.py?referrer=%{escape:%{HTTP_REFERER}}</pre>
1401 <p>Additionally, the special value <code>default</code> can be used
1402 to specify Apache httpd's simple hardcoded message. While not required
1403 under normal circumstances, <code>default</code> will restore
1404 Apache httpd's simple hardcoded message for configurations that would
1405 otherwise inherit an existing <code class="directive">ErrorDocument</code>.</p>
1407 <pre class="prettyprint lang-config">ErrorDocument 404 /cgi-bin/bad_urls.pl
1409 <Directory "/web/docs">
1410 ErrorDocument 404 default
1411 </Directory></pre>
1414 <p>Note that when you specify an <code class="directive">ErrorDocument</code>
1415 that points to a remote URL (ie. anything with a method such as
1416 <code>http</code> in front of it), Apache HTTP Server will send a redirect to the
1417 client to tell it where to find the document, even if the
1418 document ends up being on the same server. This has several
1419 implications, the most important being that the client will not
1420 receive the original error status code, but instead will
1421 receive a redirect status code. This in turn can confuse web
1422 robots and other clients which try to determine if a URL is
1423 valid using the status code. In addition, if you use a remote
1424 URL in an <code>ErrorDocument 401</code>, the client will not
1425 know to prompt the user for a password since it will not
1426 receive the 401 status code. Therefore, <strong>if you use an
1427 <code>ErrorDocument 401</code> directive, then it must refer to a local
1428 document.</strong></p>
1430 <p>Microsoft Internet Explorer (MSIE) will by default ignore
1431 server-generated error messages when they are "too small" and substitute
1432 its own "friendly" error messages. The size threshold varies depending on
1433 the type of error, but in general, if you make your error document
1434 greater than 512 bytes, then MSIE will show the server-generated
1435 error rather than masking it. More information is available in
1436 Microsoft Knowledge Base article <a href="http://support.microsoft.com/default.aspx?scid=kb;en-us;Q294807">Q294807</a>.</p>
1438 <p>Although most error messages can be overridden, there are certain
1439 circumstances where the internal messages are used regardless of the
1440 setting of <code class="directive"><a href="#errordocument">ErrorDocument</a></code>. In
1441 particular, if a malformed request is detected, normal request processing
1442 will be immediately halted and the internal error message returned.
1443 This is necessary to guard against security problems caused by
1446 <p>If you are using mod_proxy, you may wish to enable
1447 <code class="directive"><a href="../mod/mod_proxy.html#proxyerroroverride">ProxyErrorOverride</a></code> so that you can provide
1448 custom error messages on behalf of your Origin servers. If you don't enable ProxyErrorOverride,
1449 Apache httpd will not generate custom error documents for proxied content.</p>
1453 <li><a href="../custom-error.html">documentation of
1454 customizable responses</a></li>
1457 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1458 <div class="directive-section"><h2><a name="ErrorLog" id="ErrorLog">ErrorLog</a> <a name="errorlog" id="errorlog">Directive</a></h2>
1459 <table class="directive">
1460 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Location where the server will log errors</td></tr>
1461 <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>
1462 <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>
1463 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1464 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1465 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1467 <p>The <code class="directive">ErrorLog</code> directive sets the name of
1468 the file to which the server will log any errors it encounters. If
1469 the <var>file-path</var> is not absolute then it is assumed to be
1470 relative to the <code class="directive"><a href="#serverroot">ServerRoot</a></code>.</p>
1472 <pre class="prettyprint lang-config">ErrorLog "/var/log/httpd/error_log"</pre>
1475 <p>If the <var>file-path</var>
1476 begins with a pipe character "<code>|</code>" then it is assumed to be a
1477 command to spawn to handle the error log.</p>
1479 <pre class="prettyprint lang-config">ErrorLog "|/usr/local/bin/httpd_errors"</pre>
1482 <p>See the notes on <a href="../logs.html#piped">piped logs</a> for
1483 more information.</p>
1485 <p>Using <code>syslog</code> instead of a filename enables logging
1486 via syslogd(8) if the system supports it and if <code class="module"><a href="../mod/mod_syslog.html">mod_syslog</a></code>
1487 is loaded. The default is to use syslog facility <code>local7</code>,
1488 but you can override this by using the <code>syslog:<var>facility</var></code>
1489 syntax where <var>facility</var> can be one of the names usually documented in
1490 syslog(1). The facility is effectively global, and if it is changed
1491 in individual virtual hosts, the final facility specified affects the
1494 <pre class="prettyprint lang-config">ErrorLog syslog:user</pre>
1497 <p>Additional modules can provide their own ErrorLog providers. The syntax
1498 is similar to the <code>syslog</code> example above.</p>
1500 <p>SECURITY: See the <a href="../misc/security_tips.html#serverroot">security tips</a>
1501 document for details on why your security could be compromised
1502 if the directory where log files are stored is writable by
1503 anyone other than the user that starts the server.</p>
1504 <div class="warning"><h3>Note</h3>
1505 <p>When entering a file path on non-Unix platforms, care should be taken
1506 to make sure that only forward slashes are used even though the platform
1507 may allow the use of back slashes. In general it is a good idea to always
1508 use forward slashes throughout the configuration files.</p>
1513 <li><code class="directive"><a href="#loglevel">LogLevel</a></code></li>
1514 <li><a href="../logs.html">Apache HTTP Server Log Files</a></li>
1517 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1518 <div class="directive-section"><h2><a name="ErrorLogFormat" id="ErrorLogFormat">ErrorLogFormat</a> <a name="errorlogformat" id="errorlogformat">Directive</a></h2>
1519 <table class="directive">
1520 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Format specification for error log entries</td></tr>
1521 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code> ErrorLogFormat [connection|request] <var>format</var></code></td></tr>
1522 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1523 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1524 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1526 <p><code class="directive">ErrorLogFormat</code> allows to specify what
1527 supplementary information is logged in the error log in addition to the
1528 actual log message.</p>
1530 <pre class="prettyprint lang-config">#Simple example
1531 ErrorLogFormat "[%t] [%l] [pid %P] %F: %E: [client %a] %M"</pre>
1534 <p>Specifying <code>connection</code> or <code>request</code> as first
1535 parameter allows to specify additional formats, causing additional
1536 information to be logged when the first message is logged for a specific
1537 connection or request, respectively. This additional information is only
1538 logged once per connection/request. If a connection or request is processed
1539 without causing any log message, the additional information is not logged
1542 <p>It can happen that some format string items do not produce output. For
1543 example, the Referer header is only present if the log message is
1544 associated to a request and the log message happens at a time when the
1545 Referer header has already been read from the client. If no output is
1546 produced, the default behavior is to delete everything from the preceding
1547 space character to the next space character. This means the log line is
1548 implicitly divided into fields on non-whitespace to whitespace transitions.
1549 If a format string item does not produce output, the whole field is
1550 omitted. For example, if the remote address <code>%a</code> in the log
1551 format <code>[%t] [%l] [%a] %M </code> is not available, the surrounding
1552 brackets are not logged either. Space characters can be escaped with a
1553 backslash to prevent them from delimiting a field. The combination '% '
1554 (percent space) is a zero-width field delimiter that does not produce any
1557 <p>The above behavior can be changed by adding modifiers to the format
1558 string item. A <code>-</code> (minus) modifier causes a minus to be logged if the
1559 respective item does not produce any output. In once-per-connection/request
1560 formats, it is also possible to use the <code>+</code> (plus) modifier. If an
1561 item with the plus modifier does not produce any output, the whole line is
1564 <p>A number as modifier can be used to assign a log severity level to a
1565 format item. The item will only be logged if the severity of the log
1566 message is not higher than the specified log severity level. The number can
1567 range from 1 (alert) over 4 (warn) and 7 (debug) to 15 (trace8).</p>
1569 <p>For example, here's what would happen if you added modifiers to
1570 the <code>%{Referer}i</code> token, which logs the
1571 <code>Referer</code> request header.</p>
1573 <table class="bordered"><tr class="header"><th>Modified Token</th><th>Meaning</th></tr>
1575 <td><code>%-{Referer}i</code></td>
1576 <td>Logs a <code>-</code> if <code>Referer</code> is not set.</td>
1579 <td><code>%+{Referer}i</code></td>
1580 <td>Omits the entire line if <code>Referer</code> is not set.</td>
1583 <td><code>%4{Referer}i</code></td>
1584 <td>Logs the <code>Referer</code> only if the log message severity
1585 is higher than 4.</td>
1589 <p>Some format string items accept additional parameters in braces.</p>
1591 <table class="bordered"><tr class="header"><th>Format String</th> <th>Description</th></tr>
1592 <tr><td><code>%%</code></td>
1593 <td>The percent sign</td></tr>
1594 <tr class="odd"><td><code>%a</code></td>
1595 <td>Client IP address and port of the request</td></tr>
1596 <tr><td><code>%{c}a</code></td>
1597 <td>Underlying peer IP address and port of the connection (see the
1598 <code class="module"><a href="../mod/mod_remoteip.html">mod_remoteip</a></code> module)</td></tr>
1599 <tr class="odd"><td><code>%A</code></td>
1600 <td>Local IP-address and port</td></tr>
1601 <tr><td><code>%{<em>name</em>}e</code></td>
1602 <td>Request environment variable <em>name</em></td></tr>
1603 <tr class="odd"><td><code>%E</code></td>
1604 <td>APR/OS error status code and string</td></tr>
1605 <tr><td><code>%F</code></td>
1606 <td>Source file name and line number of the log call</td></tr>
1607 <tr class="odd"><td><code>%{<em>name</em>}i</code></td>
1608 <td>Request header <em>name</em></td></tr>
1609 <tr><td><code>%k</code></td>
1610 <td>Number of keep-alive requests on this connection</td></tr>
1611 <tr class="odd"><td><code>%l</code></td>
1612 <td>Loglevel of the message</td></tr>
1613 <tr><td><code>%L</code></td>
1614 <td>Log ID of the request</td></tr>
1615 <tr class="odd"><td><code>%{c}L</code></td>
1616 <td>Log ID of the connection</td></tr>
1617 <tr><td><code>%{C}L</code></td>
1618 <td>Log ID of the connection if used in connection scope, empty otherwise</td></tr>
1619 <tr class="odd"><td><code>%m</code></td>
1620 <td>Name of the module logging the message</td></tr>
1621 <tr><td><code>%M</code></td>
1622 <td>The actual log message</td></tr>
1623 <tr class="odd"><td><code>%{<em>name</em>}n</code></td>
1624 <td>Request note <em>name</em></td></tr>
1625 <tr><td><code>%P</code></td>
1626 <td>Process ID of current process</td></tr>
1627 <tr class="odd"><td><code>%T</code></td>
1628 <td>Thread ID of current thread</td></tr>
1629 <tr><td><code>%{g}T</code></td>
1630 <td>System unique thread ID of current thread (the same ID as
1631 displayed by e.g. <code>top</code>; currently Linux only)</td></tr>
1632 <tr class="odd"><td><code>%t</code></td>
1633 <td>The current time</td></tr>
1634 <tr><td><code>%{u}t</code></td>
1635 <td>The current time including micro-seconds</td></tr>
1636 <tr class="odd"><td><code>%{cu}t</code></td>
1637 <td>The current time in compact ISO 8601 format, including
1638 micro-seconds</td></tr>
1639 <tr><td><code>%v</code></td>
1640 <td>The canonical <code class="directive"><a href="#servername">ServerName</a></code>
1641 of the current server.</td></tr>
1642 <tr class="odd"><td><code>%V</code></td>
1643 <td>The server name of the server serving the request according to the
1644 <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code>
1646 <tr><td><code>\ </code> (backslash space)</td>
1647 <td>Non-field delimiting space</td></tr>
1648 <tr class="odd"><td><code>% </code> (percent space)</td>
1649 <td>Field delimiter (no output)</td></tr>
1652 <p>The log ID format <code>%L</code> produces a unique id for a connection
1653 or request. This can be used to correlate which log lines belong to the
1654 same connection or request, which request happens on which connection.
1655 A <code>%L</code> format string is also available in
1656 <code class="module"><a href="../mod/mod_log_config.html">mod_log_config</a></code> to allow to correlate access log entries
1657 with error log lines. If <code class="module"><a href="../mod/mod_unique_id.html">mod_unique_id</a></code> is loaded, its
1658 unique id will be used as log ID for requests.</p>
1660 <pre class="prettyprint lang-config">#Example (default format for threaded MPMs)
1661 ErrorLogFormat "[%{u}t] [%-m:%l] [pid %P:tid %T] %7F: %E: [client\ %a] %M% ,\ referer\ %{Referer}i"</pre>
1664 <p>This would result in error messages such as:</p>
1666 <div class="example"><p><code>
1667 [Thu May 12 08:28:57.652118 2011] [core:error] [pid 8777:tid 4326490112] [client ::1:58619] File does not exist: /usr/local/apache2/htdocs/favicon.ico
1670 <p>Notice that, as discussed above, some fields are omitted
1671 entirely because they are not defined.</p>
1673 <pre class="prettyprint lang-config">#Example (similar to the 2.2.x format)
1674 ErrorLogFormat "[%t] [%l] %7F: %E: [client\ %a] %M% ,\ referer\ %{Referer}i"</pre>
1677 <pre class="prettyprint lang-config">#Advanced example with request/connection log IDs
1678 ErrorLogFormat "[%{uc}t] [%-m:%-l] [R:%L] [C:%{C}L] %7F: %E: %M"
1679 ErrorLogFormat request "[%{uc}t] [R:%L] Request %k on C:%{c}L pid:%P tid:%T"
1680 ErrorLogFormat request "[%{uc}t] [R:%L] UA:'%+{User-Agent}i'"
1681 ErrorLogFormat request "[%{uc}t] [R:%L] Referer:'%+{Referer}i'"
1682 ErrorLogFormat connection "[%{uc}t] [C:%{c}L] local\ %a remote\ %A"</pre>
1688 <li><code class="directive"><a href="#errorlog">ErrorLog</a></code></li>
1689 <li><code class="directive"><a href="#loglevel">LogLevel</a></code></li>
1690 <li><a href="../logs.html">Apache HTTP Server Log Files</a></li>
1693 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1694 <div class="directive-section"><h2><a name="ExtendedStatus" id="ExtendedStatus">ExtendedStatus</a> <a name="extendedstatus" id="extendedstatus">Directive</a></h2>
1695 <table class="directive">
1696 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Keep track of extended status information for each
1698 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ExtendedStatus On|Off</code></td></tr>
1699 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ExtendedStatus Off[*]</code></td></tr>
1700 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
1701 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1702 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1704 <p>This option tracks additional data per worker about the
1705 currently executing request and creates a utilization summary.
1706 You can see these variables during runtime by configuring
1707 <code class="module"><a href="../mod/mod_status.html">mod_status</a></code>. Note that other modules may
1708 rely on this scoreboard.</p>
1710 <p>This setting applies to the entire server and cannot be
1711 enabled or disabled on a virtualhost-by-virtualhost basis.
1712 The collection of extended status information can slow down
1713 the server. Also note that this setting cannot be changed
1714 during a graceful restart.</p>
1717 <p>Note that loading <code class="module"><a href="../mod/mod_status.html">mod_status</a></code> will change
1718 the default behavior to ExtendedStatus On, while other
1719 third party modules may do the same. Such modules rely on
1720 collecting detailed information about the state of all workers.
1721 The default is changed by <code class="module"><a href="../mod/mod_status.html">mod_status</a></code> beginning
1722 with version 2.3.6. The previous default was always Off.</p>
1727 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1728 <div class="directive-section"><h2><a name="FileETag" id="FileETag">FileETag</a> <a name="fileetag" id="fileetag">Directive</a></h2>
1729 <table class="directive">
1730 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>File attributes used to create the ETag
1731 HTTP response header for static files</td></tr>
1732 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>FileETag <var>component</var> ...</code></td></tr>
1733 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>FileETag MTime Size</code></td></tr>
1734 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1735 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1736 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1737 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1738 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>The default used to be "INode MTime Size" in 2.3.14 and
1742 The <code class="directive">FileETag</code> directive configures the file
1743 attributes that are used to create the <code>ETag</code> (entity
1744 tag) response header field when the document is based on a static file.
1745 (The <code>ETag</code> value is used in cache management to save
1746 network bandwidth.) The
1747 <code class="directive">FileETag</code> directive allows you to choose
1748 which of these -- if any -- should be used. The recognized keywords are:
1752 <dt><strong>INode</strong></dt>
1753 <dd>The file's i-node number will be included in the calculation</dd>
1754 <dt><strong>MTime</strong></dt>
1755 <dd>The date and time the file was last modified will be included</dd>
1756 <dt><strong>Size</strong></dt>
1757 <dd>The number of bytes in the file will be included</dd>
1758 <dt><strong>All</strong></dt>
1759 <dd>All available fields will be used. This is equivalent to:
1760 <pre class="prettyprint lang-config">FileETag INode MTime Size</pre>
1762 <dt><strong>None</strong></dt>
1763 <dd>If a document is file-based, no <code>ETag</code> field will be
1764 included in the response</dd>
1767 <p>The <code>INode</code>, <code>MTime</code>, and <code>Size</code>
1768 keywords may be prefixed with either <code>+</code> or <code>-</code>,
1769 which allow changes to be made to the default setting inherited
1770 from a broader scope. Any keyword appearing without such a prefix
1771 immediately and completely cancels the inherited setting.</p>
1773 <p>If a directory's configuration includes
1774 <code>FileETag INode MTime Size</code>, and a
1775 subdirectory's includes <code>FileETag -INode</code>,
1776 the setting for that subdirectory (which will be inherited by
1777 any sub-subdirectories that don't override it) will be equivalent to
1778 <code>FileETag MTime Size</code>.</p>
1779 <div class="warning"><h3>Warning</h3>
1780 Do not change the default for directories or locations that have WebDAV
1781 enabled and use <code class="module"><a href="../mod/mod_dav_fs.html">mod_dav_fs</a></code> as a storage provider.
1782 <code class="module"><a href="../mod/mod_dav_fs.html">mod_dav_fs</a></code> uses <code>MTime Size</code>
1783 as a fixed format for <code>ETag</code> comparisons on conditional requests.
1784 These conditional requests will break if the <code>ETag</code> format is
1785 changed via <code class="directive">FileETag</code>.
1787 <div class="note"><h3>Server Side Includes</h3>
1788 An ETag is not generated for responses parsed by <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
1789 since the response entity can change without a change of the INode, MTime, or Size
1790 of the static file with embedded SSI directives.
1795 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1796 <div class="directive-section"><h2><a name="Files" id="Files"><Files></a> <a name="files" id="files">Directive</a></h2>
1797 <table class="directive">
1798 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply to matched
1800 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Files <var>filename</var>> ... </Files></code></td></tr>
1801 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1802 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1803 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1804 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1806 <p>The <code class="directive"><Files></code> directive
1807 limits the scope of the enclosed directives by filename. It is comparable
1808 to the <code class="directive"><a href="#directory"><Directory></a></code>
1809 and <code class="directive"><a href="#location"><Location></a></code>
1810 directives. It should be matched with a <code></Files></code>
1811 directive. The directives given within this section will be applied to
1812 any object with a basename (last component of filename) matching the
1813 specified filename. <code class="directive"><Files></code>
1814 sections are processed in the order they appear in the
1815 configuration file, after the <code class="directive"><a href="#directory"><Directory></a></code> sections and
1816 <code>.htaccess</code> files are read, but before <code class="directive"><a href="#location"><Location></a></code> sections. Note
1817 that <code class="directive"><Files></code> can be nested
1818 inside <code class="directive"><a href="#directory"><Directory></a></code> sections to restrict the
1819 portion of the filesystem they apply to.</p>
1821 <p>The <var>filename</var> argument should include a filename, or
1822 a wild-card string, where <code>?</code> matches any single character,
1823 and <code>*</code> matches any sequences of characters.</p>
1824 <pre class="prettyprint lang-config"><Files "cat.html">
1825 # Insert stuff that applies to cat.html here
1828 <Files "?at.*">
1829 # This would apply to cat.html, bat.html, hat.php and so on.
1830 </Files></pre>
1832 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular expressions</a>
1833 can also be used, with the addition of the
1834 <code>~</code> character. For example:</p>
1836 <pre class="prettyprint lang-config"><Files ~ "\.(gif|jpe?g|png)$">
1838 </Files></pre>
1841 <p>would match most common Internet graphics formats. <code class="directive"><a href="#filesmatch"><FilesMatch></a></code> is preferred,
1844 <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
1845 <code>.htaccess</code> files. This allows users to control access to
1846 their own files, at a file-by-file level.</p>
1851 <li><a href="../sections.html">How <Directory>, <Location>
1852 and <Files> sections work</a> for an explanation of how these
1853 different sections are combined when a request is received</li>
1856 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1857 <div class="directive-section"><h2><a name="FilesMatch" id="FilesMatch"><FilesMatch></a> <a name="filesmatch" id="filesmatch">Directive</a></h2>
1858 <table class="directive">
1859 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply to regular-expression matched
1861 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><FilesMatch <var>regex</var>> ... </FilesMatch></code></td></tr>
1862 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
1863 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
1864 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1865 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1867 <p>The <code class="directive"><FilesMatch></code> directive
1868 limits the scope of the enclosed directives by filename, just as the
1869 <code class="directive"><a href="#files"><Files></a></code> directive
1870 does. However, it accepts a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular
1871 expression</a>. For example:</p>
1873 <pre class="prettyprint lang-config"><FilesMatch ".+\.(gif|jpe?g|png)$">
1875 </FilesMatch></pre>
1878 <p>would match most common Internet graphics formats.</p>
1880 <div class="note">The <code>.+</code> at the start of the regex ensures that
1881 files named <code>.png</code>, or <code>.gif</code>, for example,
1882 are not matched.</div>
1884 <p>From 2.4.8 onwards, named groups and backreferences are captured and
1885 written to the environment with the corresponding name prefixed with
1886 "MATCH_" and in upper case. This allows elements of files to be referenced
1887 from within <a href="../expr.html">expressions</a> and modules like
1888 <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>. In order to prevent confusion, numbered
1889 (unnamed) backreferences are ignored. Use named groups instead.</p>
1891 <pre class="prettyprint lang-config"><FilesMatch "^(?<sitename>[^/]+)">
1892 require ldap-group cn=%{env:MATCH_SITENAME},ou=combined,o=Example
1893 </FilesMatch></pre>
1898 <li><a href="../sections.html">How <Directory>, <Location>
1899 and <Files> sections work</a> for an explanation of how these
1900 different sections are combined when a request is received</li>
1903 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1904 <div class="directive-section"><h2><a name="ForceType" id="ForceType">ForceType</a> <a name="forcetype" id="forcetype">Directive</a></h2>
1905 <table class="directive">
1906 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Forces all matching files to be served with the specified
1907 media type in the HTTP Content-Type header field</td></tr>
1908 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ForceType <var>media-type</var>|None</code></td></tr>
1909 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
1910 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
1911 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1912 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1914 <p>When placed into an <code>.htaccess</code> file or a
1915 <code class="directive"><a href="#directory"><Directory></a></code>, or
1916 <code class="directive"><a href="#location"><Location></a></code> or
1917 <code class="directive"><a href="#files"><Files></a></code>
1918 section, this directive forces all matching files to be served
1919 with the content type identification given by
1920 <var>media-type</var>. For example, if you had a directory full of
1921 GIF files, but did not want to label them all with <code>.gif</code>,
1922 you might want to use:</p>
1924 <pre class="prettyprint lang-config">ForceType image/gif</pre>
1927 <p>Note that this directive overrides other indirect media type
1928 associations defined in mime.types or via the
1929 <code class="directive"><a href="../mod/mod_mime.html#addtype">AddType</a></code>.</p>
1931 <p>You can also override more general
1932 <code class="directive">ForceType</code> settings
1933 by using the value of <code>None</code>:</p>
1935 <pre class="prettyprint lang-config"># force all files to be image/gif:
1936 <Location "/images">
1940 # but normal mime-type associations here:
1941 <Location "/images/mixed">
1943 </Location></pre>
1946 <p>This directive primarily overrides the content types generated for
1947 static files served out of the filesystem. For resources other than
1948 static files, where the generator of the response typically specifies
1949 a Content-Type, this directive has no effect.</p>
1952 <div class="note"><h3>Note</h3>
1953 <p>If no handler is explicitly set for a request, the specified content
1954 type will also be used as the handler name. </p>
1956 <p>When explicit directives such as
1957 <code class="directive"><a href="#sethandler">SetHandler</a></code> or
1958 <code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code> do not apply
1959 to the current request, the internal handler name normally set by those
1960 directives is instead set to the content type specified by this directive.
1963 This is a historical behavior that some third-party modules
1964 (such as mod_php) may look for a "synthetic" content type used only to
1965 signal the module to take responsibility for the matching request.
1968 <p>Configurations that rely on such "synthetic" types should be avoided.
1969 Additionally, configurations that restrict access to
1970 <code class="directive"><a href="#sethandler">SetHandler</a></code> or
1971 <code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code> should
1972 restrict access to this directive as well.</p>
1977 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1978 <div class="directive-section"><h2><a name="GprofDir" id="GprofDir">GprofDir</a> <a name="gprofdir" id="gprofdir">Directive</a></h2>
1979 <table class="directive">
1980 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Directory to write gmon.out profiling data to. </td></tr>
1981 <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>
1982 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
1983 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
1984 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
1986 <p>When the server has been compiled with gprof profiling support,
1987 <code class="directive">GprofDir</code> causes <code>gmon.out</code> files to
1988 be written to the specified directory when the process exits. If the
1989 argument ends with a percent symbol ('%'), subdirectories are created
1990 for each process id.</p>
1992 <p>This directive currently only works with the <code class="module"><a href="../mod/prefork.html">prefork</a></code>
1996 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
1997 <div class="directive-section"><h2><a name="HostnameLookups" id="HostnameLookups">HostnameLookups</a> <a name="hostnamelookups" id="hostnamelookups">Directive</a></h2>
1998 <table class="directive">
1999 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables DNS lookups on client IP addresses</td></tr>
2000 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>HostnameLookups On|Off|Double</code></td></tr>
2001 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>HostnameLookups Off</code></td></tr>
2002 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2003 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2004 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2006 <p>This directive enables DNS lookups so that host names can be
2007 logged (and passed to CGIs/SSIs in <code>REMOTE_HOST</code>).
2008 The value <code>Double</code> refers to doing double-reverse
2009 DNS lookup. That is, after a reverse lookup is performed, a forward
2010 lookup is then performed on that result. At least one of the IP
2011 addresses in the forward lookup must match the original
2012 address. (In "tcpwrappers" terminology this is called
2013 <code>PARANOID</code>.)</p>
2015 <p>Regardless of the setting, when <code class="module"><a href="../mod/mod_authz_host.html">mod_authz_host</a></code> is
2016 used for controlling access by hostname, a double reverse lookup
2017 will be performed. This is necessary for security. Note that the
2018 result of this double-reverse isn't generally available unless you
2019 set <code>HostnameLookups Double</code>. For example, if only
2020 <code>HostnameLookups On</code> and a request is made to an object
2021 that is protected by hostname restrictions, regardless of whether
2022 the double-reverse fails or not, CGIs will still be passed the
2023 single-reverse result in <code>REMOTE_HOST</code>.</p>
2025 <p>The default is <code>Off</code> in order to save the network
2026 traffic for those sites that don't truly need the reverse
2027 lookups done. It is also better for the end users because they
2028 don't have to suffer the extra latency that a lookup entails.
2029 Heavily loaded sites should leave this directive
2030 <code>Off</code>, since DNS lookups can take considerable
2031 amounts of time. The utility <code class="program"><a href="../programs/logresolve.html">logresolve</a></code>, compiled by
2032 default to the <code>bin</code> subdirectory of your installation
2033 directory, can be used to look up host names from logged IP addresses
2036 <p>Finally, if you have <a href="mod_authz_host.html#reqhost">hostname-based Require
2037 directives</a>, a hostname lookup will be performed regardless of
2038 the setting of <code>HostnameLookups</code>.</p>
2041 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2042 <div class="directive-section"><h2><a name="HttpProtocolOptions" id="HttpProtocolOptions">HttpProtocolOptions</a> <a name="httpprotocoloptions" id="httpprotocoloptions">Directive</a></h2>
2043 <table class="directive">
2044 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Modify restrictions on HTTP Request Messages</td></tr>
2045 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>HttpProtocolOptions [Strict|Unsafe] [RegisteredMethods|LenientMethods]
2046 [Allow0.9|Require1.0]</code></td></tr>
2047 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>HttpProtocolOptions Strict LenientMethods Allow0.9</code></td></tr>
2048 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2049 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2050 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2051 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.2.32 or 2.4.24 and later</td></tr>
2053 <p>This directive changes the rules applied to the HTTP Request Line
2054 (<a href="https://tools.ietf.org/html/rfc7230#section-3.1.1">RFC 7230 §3.1.1</a>) and the HTTP Request Header Fields
2055 (<a href="https://tools.ietf.org/html/rfc7230#section-3.2">RFC 7230 §3.2</a>), which are now applied by default or using
2056 the <code>Strict</code> option. Due to legacy modules, applications or
2057 custom user-agents which must be deperecated the <code>Unsafe</code>
2058 option has been added to revert to the legacy behaviors. These rules
2059 are applied prior to request processing, so must be configured at the
2060 global or default (first) matching virtual host section, by IP/port
2061 interface (and not by name) to be honored.</p>
2063 <p>Prior to the introduction of this directive, the Apache HTTP Server
2064 request message parsers were tolerant of a number of forms of input
2065 which did not conform to the protocol.
2066 <a href="https://tools.ietf.org/html/rfc7230#section-9.4">RFC 7230 §9.4 Request Splitting</a> and
2067 <a href="https://tools.ietf.org/html/rfc7230#section-9.5">§9.5 Response Smuggling</a> call out only two of the potential
2068 risks of accepting non-conformant request messages, while
2069 <a href="https://tools.ietf.org/html/rfc7230#section-3.5">RFC 7230 §3.5</a> "Message Parsing Robustness" identify the
2070 risks of accepting obscure whitespace and request message formatting.
2071 As of the introduction of this directive, all grammer rules of the
2072 specification are enforced in the default <code>Strict</code> operating
2073 mode, and the strict whitespace suggested by section 3.5 is enforced
2074 and cannot be relaxed.</p>
2076 <p>Users are strongly cautioned against toggling the <code>Unsafe</code>
2077 mode of operation, particularly on outward-facing, publicly accessible
2078 server deployments. If an interface is required for faulty monitoring
2079 or other custom service consumers running on an intranet, users should
2080 toggle the Unsafe option only on a specific virtual host configured
2081 to service their internal private network.</p>
2083 <p>Reviewing the messages logged to the <code class="directive">ErrorLog</code>,
2084 configured with <code class="directive">LogLevel</code> <code>debug</code> level,
2085 can help identify such faulty requests along with their origin.
2086 Users should pay particular attention to the 400 responses in the access
2087 log for invalid requests which were unexpectedly rejected.</p>
2089 <p><a href="https://tools.ietf.org/html/rfc7231#section-4.1">RFC 7231 §4.1</a> "Request Methods" "Overview" requires that
2090 origin servers shall respond with an error when an unsupported method
2091 is encountered in the request line. This already happens when the
2092 <code>LenientMethods</code> option is used, but administrators may wish
2093 to toggle the <code>RegisteredMethods</code> option and register any
2094 non-standard methods using the <code class="directive">RegisterHttpMethod</code>
2095 directive, particularly if the <code>Unsafe</code> option has been toggled.
2096 The <code>RegisteredMethods</code> option should <strong>not</strong>
2097 be toggled for forward proxy hosts, as the methods supported by the
2098 origin servers are unknown to the proxy server.</p>
2100 <p><a href="https://tools.ietf.org/html/rfc2616#section-19.6">RFC 2616 §19.6</a> "Compatibility With Previous Versions" had
2101 encouraged HTTP servers to support legacy HTTP/0.9 requests. RFC 7230
2102 superceeds this with "The expectation to support HTTP/0.9 requests has
2103 been removed" and offers additional comments in
2104 <a href="https://tools.ietf.org/html/rfc7230#appendix-A">RFC 7230 Appendix A</a>. The <code>Require1.0</code> option allows
2105 the user to remove support of the default <code>Allow0.9</code> option's
2109 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2110 <div class="directive-section"><h2><a name="If" id="If"><If></a> <a name="if" id="if">Directive</a></h2>
2111 <table class="directive">
2112 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only if a condition is
2113 satisfied by a request at runtime</td></tr>
2114 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><If <var>expression</var>> ... </If></code></td></tr>
2115 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2116 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2117 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2118 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2120 <p>The <code class="directive"><If></code> directive
2121 evaluates an expression at runtime, and applies the enclosed
2122 directives if and only if the expression evaluates to true.
2125 <pre class="prettyprint lang-config"><If "-z req('Host')"></pre>
2128 <p>would match HTTP/1.0 requests without a <var>Host:</var> header.
2129 Expressions may contain various shell-like operators for string
2130 comparison (<code>==</code>, <code>!=</code>, <code><</code>, ...),
2131 integer comparison (<code>-eq</code>, <code>-ne</code>, ...),
2132 and others (<code>-n</code>, <code>-z</code>, <code>-f</code>, ...).
2133 It is also possible to use regular expressions, </p>
2135 <pre class="prettyprint lang-config"><If "%{QUERY_STRING} =~ /(delete|commit)=.*?elem/"></pre>
2138 <p>shell-like pattern matches and many other operations. These operations
2139 can be done on request headers (<code>req</code>), environment variables
2140 (<code>env</code>), and a large number of other properties. The full
2141 documentation is available in <a href="../expr.html">Expressions in
2142 Apache HTTP Server</a>.</p>
2144 <p>Only directives that support the <a href="directive-dict.html#Context">directory context</a> can be used within this configuration section.</p>
2146 <div class="warning">
2147 Certain variables, such as <code>CONTENT_TYPE</code> and other
2148 response headers, are set after <If> conditions have already
2149 been evaluated, and so will not be available to use in this
2156 <li><a href="../expr.html">Expressions in Apache HTTP Server</a>,
2157 for a complete reference and more examples.</li>
2158 <li><code class="directive"><a href="#elseif"><ElseIf></a></code></li>
2159 <li><code class="directive"><a href="#else"><Else></a></code></li>
2160 <li><a href="../sections.html">How <Directory>, <Location>,
2161 <Files> sections work</a> for an explanation of how these
2162 different sections are combined when a request is received.
2163 <code class="directive"><If></code>,
2164 <code class="directive"><ElseIf></code>, and
2165 <code class="directive"><Else></code> are applied last.</li>
2168 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2169 <div class="directive-section"><h2><a name="IfDefine" id="IfDefine"><IfDefine></a> <a name="ifdefine" id="ifdefine">Directive</a></h2>
2170 <table class="directive">
2171 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Encloses directives that will be processed only
2172 if a test is true at startup</td></tr>
2173 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><IfDefine [!]<var>parameter-name</var>> ...
2174 </IfDefine></code></td></tr>
2175 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2176 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2177 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2178 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2180 <p>The <code><IfDefine <var>test</var>>...</IfDefine>
2181 </code> section is used to mark directives that are conditional. The
2182 directives within an <code class="directive"><IfDefine></code>
2183 section are only processed if the <var>test</var> is true. If <var>
2184 test</var> is false, everything between the start and end markers is
2187 <p>The <var>test</var> in the <code class="directive"><IfDefine></code> section directive can be one of two forms:</p>
2190 <li><var>parameter-name</var></li>
2192 <li><code>!</code><var>parameter-name</var></li>
2195 <p>In the former case, the directives between the start and end
2196 markers are only processed if the parameter named
2197 <var>parameter-name</var> is defined. The second format reverses
2198 the test, and only processes the directives if
2199 <var>parameter-name</var> is <strong>not</strong> defined.</p>
2201 <p>The <var>parameter-name</var> argument is a define as given on the
2202 <code class="program"><a href="../programs/httpd.html">httpd</a></code> command line via <code>-D<var>parameter</var>
2203 </code> at the time the server was started or by the <code class="directive"><a href="#define">Define</a></code> directive.</p>
2205 <p><code class="directive"><IfDefine></code> sections are
2206 nest-able, which can be used to implement simple
2207 multiple-parameter tests. Example:</p>
2209 <div class="example"><p><code>httpd -DReverseProxy -DUseCache -DMemCache ...</code></p></div>
2210 <pre class="prettyprint lang-config"><IfDefine ReverseProxy>
2211 LoadModule proxy_module modules/mod_proxy.so
2212 LoadModule proxy_http_module modules/mod_proxy_http.so
2213 <IfDefine UseCache>
2214 LoadModule cache_module modules/mod_cache.so
2215 <IfDefine MemCache>
2216 LoadModule mem_cache_module modules/mod_mem_cache.so
2218 <IfDefine !MemCache>
2219 LoadModule cache_disk_module modules/mod_cache_disk.so
2222 </IfDefine></pre>
2226 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2227 <div class="directive-section"><h2><a name="IfFile" id="IfFile"><IfFile></a> <a name="iffile" id="iffile">Directive</a></h2>
2228 <table class="directive">
2229 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Encloses directives that will be processed only
2230 if file exists at startup</td></tr>
2231 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><IfFile [!]<var>parameter-name</var>> ...
2232 </IfFile></code></td></tr>
2233 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2234 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2235 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2237 <p>The <code><IfFile <var>filename</var>>...</IfFile>
2238 </code> section is used to mark directives that are conditional on
2239 the existence of a file on disk. The directives within an
2240 <code class="directive"><IfFile></code> section are only
2241 processed if the <var>filename</var> exists. If <var> filename</var>
2242 doesn't exist, everything between the start and end markers is
2243 ignored. <var>filename</var> can be an absolute path or a path
2244 relative to the server root.</p>
2246 <p>The <var>filename</var> in the <code class="directive"><IfFile
2247 ></code> section directive can take the same forms as the
2248 <var>test</var> variable in the <code class="directive"><IfDefine
2249 ></code> section, i.e. the test can be negated if the <code>
2250 !</code> character is placed directly before <var>filename</var>.
2253 <p>If a relative <var>filename</var> is supplied, the check is
2254 <code class="directive">ServerRoot</code> relative. In the case where
2255 this directive occurs before the <code class="directive">ServerRoot</code>,
2256 the path will be checked relative to the compiled-in server root or
2257 the server root passed in on the command line via the <code>-d</code>
2262 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2263 <div class="directive-section"><h2><a name="IfModule" id="IfModule"><IfModule></a> <a name="ifmodule" id="ifmodule">Directive</a></h2>
2264 <table class="directive">
2265 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Encloses directives that are processed conditional on the
2266 presence or absence of a specific module</td></tr>
2267 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><IfModule [!]<var>module-file</var>|<var>module-identifier</var>> ...
2268 </IfModule></code></td></tr>
2269 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2270 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2271 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2272 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2274 <p>The <code><IfModule <var>test</var>>...</IfModule></code>
2275 section is used to mark directives that are conditional on the presence of
2276 a specific module. The directives within an <code class="directive"><IfModule></code> section are only processed if the <var>test</var>
2277 is true. If <var>test</var> is false, everything between the start and
2278 end markers is ignored.</p>
2280 <p>The <var>test</var> in the <code class="directive"><IfModule></code> section directive can be one of two forms:</p>
2283 <li><var>module</var></li>
2285 <li>!<var>module</var></li>
2288 <p>In the former case, the directives between the start and end
2289 markers are only processed if the module named <var>module</var>
2290 is included in Apache httpd -- either compiled in or
2291 dynamically loaded using <code class="directive"><a href="../mod/mod_so.html#loadmodule">LoadModule</a></code>. The second format reverses the test,
2292 and only processes the directives if <var>module</var> is
2293 <strong>not</strong> included.</p>
2295 <p>The <var>module</var> argument can be either the module identifier or
2296 the file name of the module, at the time it was compiled. For example,
2297 <code>rewrite_module</code> is the identifier and
2298 <code>mod_rewrite.c</code> is the file name. If a module consists of
2299 several source files, use the name of the file containing the string
2300 <code>STANDARD20_MODULE_STUFF</code>.</p>
2302 <p><code class="directive"><IfModule></code> sections are
2303 nest-able, which can be used to implement simple multiple-module
2306 <div class="note">This section should only be used if you need to have one
2307 configuration file that works whether or not a specific module
2308 is available. In normal operation, directives need not be
2309 placed in <code class="directive"><IfModule></code>
2313 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2314 <div class="directive-section"><h2><a name="Include" id="Include">Include</a> <a name="include" id="include">Directive</a></h2>
2315 <table class="directive">
2316 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Includes other configuration files from within
2317 the server configuration files</td></tr>
2318 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Include <var>file-path</var>|<var>directory-path</var>|<var>wildcard</var></code></td></tr>
2319 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2320 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2321 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2322 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Directory
2323 wildcard matching available in 2.3.6 and later</td></tr>
2325 <p>This directive allows inclusion of other configuration files
2326 from within the server configuration files.</p>
2328 <p>Shell-style (<code>fnmatch()</code>) wildcard characters can be used
2329 in the filename or directory parts of the path to include several files
2330 at once, in alphabetical order. In addition, if
2331 <code class="directive">Include</code> points to a directory, rather than a file,
2332 Apache httpd will read all files in that directory and any subdirectory.
2333 However, including entire directories is not recommended, because it is
2334 easy to accidentally leave temporary files in a directory that can cause
2335 <code class="program"><a href="../programs/httpd.html">httpd</a></code> to fail. Instead, we encourage you to use the
2336 wildcard syntax shown below, to include files that match a particular
2337 pattern, such as *.conf, for example.</p>
2339 <p>The <code class="directive"><a href="#include">Include</a></code> directive will
2340 <strong>fail with an error</strong> if a wildcard expression does not
2341 match any file. The <code class="directive"><a href="#includeoptional">IncludeOptional</a></code>
2342 directive can be used if non-matching wildcards should be ignored.</p>
2344 <p>The file path specified may be an absolute path, or may be relative
2345 to the <code class="directive"><a href="#serverroot">ServerRoot</a></code> directory.</p>
2349 <pre class="prettyprint lang-config">Include /usr/local/apache2/conf/ssl.conf
2350 Include /usr/local/apache2/conf/vhosts/*.conf</pre>
2353 <p>Or, providing paths relative to your <code class="directive"><a href="#serverroot">ServerRoot</a></code> directory:</p>
2355 <pre class="prettyprint lang-config">Include conf/ssl.conf
2356 Include conf/vhosts/*.conf</pre>
2359 <p>Wildcards may be included in the directory or file portion of the
2360 path. This example will fail if there is no subdirectory in conf/vhosts
2361 that contains at least one *.conf file:</p>
2363 <pre class="prettyprint lang-config">Include conf/vhosts/*/*.conf</pre>
2366 <p>Alternatively, the following command will just be ignored in case of
2367 missing files or directories:</p>
2369 <pre class="prettyprint lang-config">IncludeOptional conf/vhosts/*/*.conf</pre>
2375 <li><code class="directive"><a href="#includeoptional">IncludeOptional</a></code></li>
2376 <li><code class="program"><a href="../programs/apachectl.html">apachectl</a></code></li>
2379 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2380 <div class="directive-section"><h2><a name="IncludeOptional" id="IncludeOptional">IncludeOptional</a> <a name="includeoptional" id="includeoptional">Directive</a></h2>
2381 <table class="directive">
2382 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Includes other configuration files from within
2383 the server configuration files</td></tr>
2384 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>IncludeOptional <var>file-path</var>|<var>directory-path</var>|<var>wildcard</var></code></td></tr>
2385 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
2386 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2387 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2388 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in 2.3.6 and later</td></tr>
2390 <p>This directive allows inclusion of other configuration files
2391 from within the server configuration files. It works identically to the
2392 <code class="directive"><a href="#include">Include</a></code> directive, with the
2393 exception that if wildcards do not match any file or directory, the
2394 <code class="directive"><a href="#includeoptional">IncludeOptional</a></code> directive will be
2395 silently ignored instead of causing an error.</p>
2399 <li><code class="directive"><a href="#include">Include</a></code></li>
2400 <li><code class="program"><a href="../programs/apachectl.html">apachectl</a></code></li>
2403 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2404 <div class="directive-section"><h2><a name="KeepAlive" id="KeepAlive">KeepAlive</a> <a name="keepalive" id="keepalive">Directive</a></h2>
2405 <table class="directive">
2406 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables HTTP persistent connections</td></tr>
2407 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>KeepAlive On|Off</code></td></tr>
2408 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>KeepAlive On</code></td></tr>
2409 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2410 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2411 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2413 <p>The Keep-Alive extension to HTTP/1.0 and the persistent
2414 connection feature of HTTP/1.1 provide long-lived HTTP sessions
2415 which allow multiple requests to be sent over the same TCP
2416 connection. In some cases this has been shown to result in an
2417 almost 50% speedup in latency times for HTML documents with
2418 many images. To enable Keep-Alive connections, set
2419 <code>KeepAlive On</code>.</p>
2421 <p>For HTTP/1.0 clients, Keep-Alive connections will only be
2422 used if they are specifically requested by a client. In
2423 addition, a Keep-Alive connection with an HTTP/1.0 client can
2424 only be used when the length of the content is known in
2425 advance. This implies that dynamic content such as CGI output,
2426 SSI pages, and server-generated directory listings will
2427 generally not use Keep-Alive connections to HTTP/1.0 clients.
2428 For HTTP/1.1 clients, persistent connections are the default
2429 unless otherwise specified. If the client requests it, chunked
2430 encoding will be used in order to send content of unknown
2431 length over persistent connections.</p>
2433 <p>When a client uses a Keep-Alive connection, it will be counted
2434 as a single "request" for the <code class="directive"><a href="../mod/mpm_common.html#maxconnectionsperchild">MaxConnectionsPerChild</a></code> directive, regardless
2435 of how many requests are sent using the connection.</p>
2439 <li><code class="directive"><a href="#maxkeepaliverequests">MaxKeepAliveRequests</a></code></li>
2442 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2443 <div class="directive-section"><h2><a name="KeepAliveTimeout" id="KeepAliveTimeout">KeepAliveTimeout</a> <a name="keepalivetimeout" id="keepalivetimeout">Directive</a></h2>
2444 <table class="directive">
2445 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Amount of time the server will wait for subsequent
2446 requests on a persistent connection</td></tr>
2447 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>KeepAliveTimeout <var>num</var>[ms]</code></td></tr>
2448 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>KeepAliveTimeout 5</code></td></tr>
2449 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2450 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2451 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2453 <p>The number of seconds Apache httpd will wait for a subsequent
2454 request before closing the connection. By adding a postfix of ms the
2455 timeout can be also set in milliseconds. Once a request has been
2456 received, the timeout value specified by the
2457 <code class="directive"><a href="#timeout">Timeout</a></code> directive applies.</p>
2459 <p>Setting <code class="directive">KeepAliveTimeout</code> to a high value
2460 may cause performance problems in heavily loaded servers. The
2461 higher the timeout, the more server processes will be kept
2462 occupied waiting on connections with idle clients.</p>
2464 <p>If <code class="directive">KeepAliveTimeout</code> is <strong>not</strong>
2465 set for a name-based virtual host, the value of the first defined
2466 virtual host best matching the local IP and port will be used.</p>
2469 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2470 <div class="directive-section"><h2><a name="Limit" id="Limit"><Limit></a> <a name="limit" id="limit">Directive</a></h2>
2471 <table class="directive">
2472 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restrict enclosed access controls to only certain HTTP
2474 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Limit <var>method</var> [<var>method</var>] ... > ...
2475 </Limit></code></td></tr>
2476 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
2477 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig, Limit</td></tr>
2478 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2479 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2481 <p>Access controls are normally effective for
2482 <strong>all</strong> access methods, and this is the usual
2483 desired behavior. <strong>In the general case, access control
2484 directives should not be placed within a
2485 <code class="directive"><Limit></code> section.</strong></p>
2487 <p>The purpose of the <code class="directive"><Limit></code>
2488 directive is to restrict the effect of the access controls to the
2489 nominated HTTP methods. For all other methods, the access
2490 restrictions that are enclosed in the <code class="directive"><Limit></code> bracket <strong>will have no
2491 effect</strong>. The following example applies the access control
2492 only to the methods <code>POST</code>, <code>PUT</code>, and
2493 <code>DELETE</code>, leaving all other methods unprotected:</p>
2495 <pre class="prettyprint lang-config"><Limit POST PUT DELETE>
2497 </Limit></pre>
2500 <p>The method names listed can be one or more of: <code>GET</code>,
2501 <code>POST</code>, <code>PUT</code>, <code>DELETE</code>,
2502 <code>CONNECT</code>, <code>OPTIONS</code>,
2503 <code>PATCH</code>, <code>PROPFIND</code>, <code>PROPPATCH</code>,
2504 <code>MKCOL</code>, <code>COPY</code>, <code>MOVE</code>,
2505 <code>LOCK</code>, and <code>UNLOCK</code>. <strong>The method name is
2506 case-sensitive.</strong> If <code>GET</code> is used, it will also
2507 restrict <code>HEAD</code> requests. The <code>TRACE</code> method
2508 cannot be limited (see <code class="directive"><a href="#traceenable">TraceEnable</a></code>).</p>
2510 <div class="warning">A <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> section should always be
2511 used in preference to a <code class="directive"><Limit></code>
2512 section when restricting access, since a <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> section provides protection
2513 against arbitrary methods.</div>
2515 <p>The <code class="directive"><Limit></code> and
2516 <code class="directive"><a href="#limitexcept"><LimitExcept></a></code>
2517 directives may be nested. In this case, each successive level of
2518 <code class="directive"><Limit></code> or <code class="directive"><a href="#limitexcept"><LimitExcept></a></code> directives must
2519 further restrict the set of methods to which access controls apply.</p>
2521 <div class="warning">When using
2522 <code class="directive"><Limit></code> or
2523 <code class="directive"><LimitExcept></code> directives with
2524 the <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code> directive,
2525 note that the first <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code>
2526 to succeed authorizes the request, regardless of the presence of other
2527 <code class="directive"><a href="../mod/mod_authz_core.html#require">Require</a></code> directives.</div>
2529 <p>For example, given the following configuration, all users will
2530 be authorized for <code>POST</code> requests, and the
2531 <code>Require group editors</code> directive will be ignored
2534 <pre class="prettyprint lang-config"><LimitExcept GET>
2536 </LimitExcept>
2538 Require group editors
2539 </Limit></pre>
2543 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2544 <div class="directive-section"><h2><a name="LimitExcept" id="LimitExcept"><LimitExcept></a> <a name="limitexcept" id="limitexcept">Directive</a></h2>
2545 <table class="directive">
2546 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restrict access controls to all HTTP methods
2547 except the named ones</td></tr>
2548 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><LimitExcept <var>method</var> [<var>method</var>] ... > ...
2549 </LimitExcept></code></td></tr>
2550 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
2551 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>AuthConfig, Limit</td></tr>
2552 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2553 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2555 <p><code class="directive"><LimitExcept></code> and
2556 <code></LimitExcept></code> are used to enclose
2557 a group of access control directives which will then apply to any
2558 HTTP access method <strong>not</strong> listed in the arguments;
2559 i.e., it is the opposite of a <code class="directive"><a href="#limit"><Limit></a></code> section and can be used to control
2560 both standard and nonstandard/unrecognized methods. See the
2561 documentation for <code class="directive"><a href="#limit"><Limit></a></code> for more details.</p>
2565 <pre class="prettyprint lang-config"><LimitExcept POST GET>
2567 </LimitExcept></pre>
2572 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2573 <div class="directive-section"><h2><a name="LimitInternalRecursion" id="LimitInternalRecursion">LimitInternalRecursion</a> <a name="limitinternalrecursion" id="limitinternalrecursion">Directive</a></h2>
2574 <table class="directive">
2575 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determine maximum number of internal redirects and nested
2576 subrequests</td></tr>
2577 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitInternalRecursion <var>number</var> [<var>number</var>]</code></td></tr>
2578 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitInternalRecursion 10</code></td></tr>
2579 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2580 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2581 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2583 <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
2584 redirects the original request to a CGI script. A subrequest is Apache httpd's
2585 mechanism to find out what would happen for some URI if it were requested.
2586 For example, <code class="module"><a href="../mod/mod_dir.html">mod_dir</a></code> uses subrequests to look for the
2587 files listed in the <code class="directive"><a href="../mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>
2590 <p><code class="directive">LimitInternalRecursion</code> prevents the server
2591 from crashing when entering an infinite loop of internal redirects or
2592 subrequests. Such loops are usually caused by misconfigurations.</p>
2594 <p>The directive stores two different limits, which are evaluated on
2595 per-request basis. The first <var>number</var> is the maximum number of
2596 internal redirects that may follow each other. The second <var>number</var>
2597 determines how deeply subrequests may be nested. If you specify only one
2598 <var>number</var>, it will be assigned to both limits.</p>
2600 <pre class="prettyprint lang-config">LimitInternalRecursion 5</pre>
2604 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2605 <div class="directive-section"><h2><a name="LimitRequestBody" id="LimitRequestBody">LimitRequestBody</a> <a name="limitrequestbody" id="limitrequestbody">Directive</a></h2>
2606 <table class="directive">
2607 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Restricts the total size of the HTTP request body sent
2608 from the client</td></tr>
2609 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestBody <var>bytes</var></code></td></tr>
2610 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestBody 0</code></td></tr>
2611 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2612 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2613 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2614 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2616 <p>This directive specifies the number of <var>bytes</var> from 0
2617 (meaning unlimited) to 2147483647 (2GB) that are allowed in a
2618 request body. See the note below for the limited applicability
2619 to proxy requests.</p>
2621 <p>The <code class="directive">LimitRequestBody</code> directive allows
2622 the user to set a limit on the allowed size of an HTTP request
2623 message body within the context in which the directive is given
2624 (server, per-directory, per-file or per-location). If the client
2625 request exceeds that limit, the server will return an error
2626 response instead of servicing the request. The size of a normal
2627 request message body will vary greatly depending on the nature of
2628 the resource and the methods allowed on that resource. CGI scripts
2629 typically use the message body for retrieving form information.
2630 Implementations of the <code>PUT</code> method will require
2631 a value at least as large as any representation that the server
2632 wishes to accept for that resource.</p>
2634 <p>This directive gives the server administrator greater
2635 control over abnormal client request behavior, which may be
2636 useful for avoiding some forms of denial-of-service
2639 <p>If, for example, you are permitting file upload to a particular
2640 location and wish to limit the size of the uploaded file to 100K,
2641 you might use the following directive:</p>
2643 <pre class="prettyprint lang-config">LimitRequestBody 102400</pre>
2646 <div class="note"><p>For a full description of how this directive is interpreted by
2647 proxy requests, see the <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> documentation.</p>
2652 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2653 <div class="directive-section"><h2><a name="LimitRequestFields" id="LimitRequestFields">LimitRequestFields</a> <a name="limitrequestfields" id="limitrequestfields">Directive</a></h2>
2654 <table class="directive">
2655 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the number of HTTP request header fields that
2656 will be accepted from the client</td></tr>
2657 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestFields <var>number</var></code></td></tr>
2658 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestFields 100</code></td></tr>
2659 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2660 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2661 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2663 <p><var>Number</var> is an integer from 0 (meaning unlimited) to
2664 32767. The default value is defined by the compile-time
2665 constant <code>DEFAULT_LIMIT_REQUEST_FIELDS</code> (100 as
2668 <p>The <code class="directive">LimitRequestFields</code> directive allows
2669 the server administrator to modify the limit on the number of
2670 request header fields allowed in an HTTP request. A server needs
2671 this value to be larger than the number of fields that a normal
2672 client request might include. The number of request header fields
2673 used by a client rarely exceeds 20, but this may vary among
2674 different client implementations, often depending upon the extent
2675 to which a user has configured their browser to support detailed
2676 content negotiation. Optional HTTP extensions are often expressed
2677 using request header fields.</p>
2679 <p>This directive gives the server administrator greater
2680 control over abnormal client request behavior, which may be
2681 useful for avoiding some forms of denial-of-service attacks.
2682 The value should be increased if normal clients see an error
2683 response from the server that indicates too many fields were
2684 sent in the request.</p>
2688 <pre class="prettyprint lang-config">LimitRequestFields 50</pre>
2691 <div class="warning"><h3>Warning</h3>
2692 <p> When name-based virtual hosting is used, the value for this
2693 directive is taken from the default (first-listed) virtual host for the
2694 local IP and port combination.</p>
2699 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2700 <div class="directive-section"><h2><a name="LimitRequestFieldSize" id="LimitRequestFieldSize">LimitRequestFieldSize</a> <a name="limitrequestfieldsize" id="limitrequestfieldsize">Directive</a></h2>
2701 <table class="directive">
2702 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the size of the HTTP request header allowed from the
2704 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestFieldSize <var>bytes</var></code></td></tr>
2705 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestFieldSize 8190</code></td></tr>
2706 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2707 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2708 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2710 <p>This directive specifies the number of <var>bytes</var>
2711 that will be allowed in an HTTP request header.</p>
2713 <p>The <code class="directive">LimitRequestFieldSize</code> directive
2714 allows the server administrator to set the limit
2715 on the allowed size of an HTTP request header field. A server
2716 needs this value to be large enough to hold any one header field
2717 from a normal client request. The size of a normal request header
2718 field will vary greatly among different client implementations,
2719 often depending upon the extent to which a user has configured
2720 their browser to support detailed content negotiation. SPNEGO
2721 authentication headers can be up to 12392 bytes.</p>
2723 <p>This directive gives the server administrator greater
2724 control over abnormal client request behavior, which may be
2725 useful for avoiding some forms of denial-of-service attacks.</p>
2729 <pre class="prettyprint lang-config">LimitRequestFieldSize 4094</pre>
2732 <div class="note">Under normal conditions, the value should not be changed from
2735 <div class="warning"><h3>Warning</h3>
2736 <p> When name-based virtual hosting is used, the value for this
2737 directive is taken from the default (first-listed) virtual host best
2738 matching the current IP address and port combination.</p>
2742 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2743 <div class="directive-section"><h2><a name="LimitRequestLine" id="LimitRequestLine">LimitRequestLine</a> <a name="limitrequestline" id="limitrequestline">Directive</a></h2>
2744 <table class="directive">
2745 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limit the size of the HTTP request line that will be accepted
2746 from the client</td></tr>
2747 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitRequestLine <var>bytes</var></code></td></tr>
2748 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitRequestLine 8190</code></td></tr>
2749 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2750 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2751 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2753 <p>This directive sets the number of <var>bytes</var> that will be
2754 allowed on the HTTP request-line.</p>
2756 <p>The <code class="directive">LimitRequestLine</code> directive allows
2757 the server administrator to set the limit on the allowed size
2758 of a client's HTTP request-line. Since the request-line consists of the
2759 HTTP method, URI, and protocol version, the
2760 <code class="directive">LimitRequestLine</code> directive places a
2761 restriction on the length of a request-URI allowed for a request
2762 on the server. A server needs this value to be large enough to
2763 hold any of its resource names, including any information that
2764 might be passed in the query part of a <code>GET</code> request.</p>
2766 <p>This directive gives the server administrator greater
2767 control over abnormal client request behavior, which may be
2768 useful for avoiding some forms of denial-of-service attacks.</p>
2772 <pre class="prettyprint lang-config">LimitRequestLine 4094</pre>
2775 <div class="note">Under normal conditions, the value should not be changed from
2778 <div class="warning"><h3>Warning</h3>
2779 <p> When name-based virtual hosting is used, the value for this
2780 directive is taken from the default (first-listed) virtual host best
2781 matching the current IP address and port combination.</p>
2786 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2787 <div class="directive-section"><h2><a name="LimitXMLRequestBody" id="LimitXMLRequestBody">LimitXMLRequestBody</a> <a name="limitxmlrequestbody" id="limitxmlrequestbody">Directive</a></h2>
2788 <table class="directive">
2789 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the size of an XML-based request body</td></tr>
2790 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LimitXMLRequestBody <var>bytes</var></code></td></tr>
2791 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LimitXMLRequestBody 1000000</code></td></tr>
2792 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
2793 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
2794 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2795 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2797 <p>Limit (in bytes) on maximum size of an XML-based request
2798 body. A value of <code>0</code> will disable any checking.</p>
2802 <pre class="prettyprint lang-config">LimitXMLRequestBody 0</pre>
2807 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2808 <div class="directive-section"><h2><a name="Location" id="Location"><Location></a> <a name="location" id="location">Directive</a></h2>
2809 <table class="directive">
2810 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Applies the enclosed directives only to matching
2812 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><Location
2813 <var>URL-path</var>|<var>URL</var>> ... </Location></code></td></tr>
2814 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2815 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2816 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2818 <p>The <code class="directive"><Location></code> directive
2819 limits the scope of the enclosed directives by URL. It is similar to the
2820 <code class="directive"><a href="#directory"><Directory></a></code>
2821 directive, and starts a subsection which is terminated with a
2822 <code></Location></code> directive. <code class="directive"><Location></code> sections are processed in the
2823 order they appear in the configuration file, after the <code class="directive"><a href="#directory"><Directory></a></code> sections and
2824 <code>.htaccess</code> files are read, and after the <code class="directive"><a href="#files"><Files></a></code> sections.</p>
2826 <p><code class="directive"><Location></code> sections operate
2827 completely outside the filesystem. This has several consequences.
2828 Most importantly, <code class="directive"><Location></code>
2829 directives should not be used to control access to filesystem
2830 locations. Since several different URLs may map to the same
2831 filesystem location, such access controls may by circumvented.</p>
2833 <p>The enclosed directives will be applied to the request if the path component
2834 of the URL meets <em>any</em> of the following criteria:
2837 <li>The specified location matches exactly the path component of the URL.
2839 <li>The specified location, which ends in a forward slash, is a prefix
2840 of the path component of the URL (treated as a context root).
2842 <li>The specified location, with the addition of a trailing slash, is a
2843 prefix of the path component of the URL (also treated as a context root).
2847 In the example below, where no trailing slash is used, requests to
2848 /private1, /private1/ and /private1/file.txt will have the enclosed
2849 directives applied, but /private1other would not.
2851 <pre class="prettyprint lang-config"><Location "/private1">
2853 </Location></pre>
2856 In the example below, where a trailing slash is used, requests to
2857 /private2/ and /private2/file.txt will have the enclosed
2858 directives applied, but /private2 and /private2other would not.
2860 <pre class="prettyprint lang-config"><Location "/private2<em>/</em>">
2862 </Location></pre>
2865 <div class="note"><h3>When to use <code class="directive"><Location></code></h3>
2867 <p>Use <code class="directive"><Location></code> to apply
2868 directives to content that lives outside the filesystem. For
2869 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
2870 <code><Location "/"></code>, which is an easy way to
2871 apply a configuration to the entire server.</p>
2874 <p>For all origin (non-proxy) requests, the URL to be matched is a
2875 URL-path of the form <code>/path/</code>. <em>No scheme, hostname,
2876 port, or query string may be included.</em> For proxy requests, the
2877 URL to be matched is of the form
2878 <code>scheme://servername/path</code>, and you must include the
2881 <p>The URL may use wildcards. In a wild-card string, <code>?</code> matches
2882 any single character, and <code>*</code> matches any sequences of
2883 characters. Neither wildcard character matches a / in the URL-path.</p>
2885 <p><a class="glossarylink" href="../glossary.html#regex" title="see glossary">Regular expressions</a>
2886 can also be used, with the addition of the <code>~</code>
2887 character. For example:</p>
2889 <pre class="prettyprint lang-config"><Location ~ "/(extra|special)/data">
2891 </Location></pre>
2894 <p>would match URLs that contained the substring <code>/extra/data</code>
2895 or <code>/special/data</code>. The directive <code class="directive"><a href="#locationmatch"><LocationMatch></a></code> behaves
2896 identical to the regex version of <code class="directive"><Location></code>, and is preferred, for the
2897 simple reason that <code>~</code> is hard to distinguish from
2898 <code>-</code> in many fonts.</p>
2900 <p>The <code class="directive"><Location></code>
2901 functionality is especially useful when combined with the
2902 <code class="directive"><a href="#sethandler">SetHandler</a></code>
2903 directive. For example, to enable status requests but allow them
2904 only from browsers at <code>example.com</code>, you might use:</p>
2906 <pre class="prettyprint lang-config"><Location "/status">
2907 SetHandler server-status
2908 Require host example.com
2909 </Location></pre>
2912 <div class="note"><h3>Note about / (slash)</h3>
2913 <p>The slash character has special meaning depending on where in a
2914 URL it appears. People may be used to its behavior in the filesystem
2915 where multiple adjacent slashes are frequently collapsed to a single
2916 slash (<em>i.e.</em>, <code>/home///foo</code> is the same as
2917 <code>/home/foo</code>). In URL-space this is not necessarily true.
2918 The <code class="directive"><a href="#locationmatch"><LocationMatch></a></code>
2919 directive and the regex version of <code class="directive"><Location></code> require you to explicitly specify multiple
2920 slashes if that is your intention.</p>
2922 <p>For example, <code><LocationMatch "^/abc"></code> would match
2923 the request URL <code>/abc</code> but not the request URL <code>
2924 //abc</code>. The (non-regex) <code class="directive"><Location></code> directive behaves similarly when used for
2925 proxy requests. But when (non-regex) <code class="directive"><Location></code> is used for non-proxy requests it will
2926 implicitly match multiple slashes with a single slash. For example,
2927 if you specify <code><Location "/abc/def"></code> and the
2928 request is to <code>/abc//def</code> then it will match.</p>
2933 <li><a href="../sections.html">How <Directory>, <Location>
2934 and <Files> sections work</a> for an explanation of how these
2935 different sections are combined when a request is received.</li>
2936 <li><code class="directive"><a href="#locationmatch">LocationMatch</a></code></li>
2939 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2940 <div class="directive-section"><h2><a name="LocationMatch" id="LocationMatch"><LocationMatch></a> <a name="locationmatch" id="locationmatch">Directive</a></h2>
2941 <table class="directive">
2942 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Applies the enclosed directives only to regular-expression
2943 matching URLs</td></tr>
2944 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><LocationMatch
2945 <var>regex</var>> ... </LocationMatch></code></td></tr>
2946 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
2947 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
2948 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
2950 <p>The <code class="directive"><LocationMatch></code> directive
2951 limits the scope of the enclosed directives by URL, in an identical manner
2952 to <code class="directive"><a href="#location"><Location></a></code>. However,
2953 it takes a <a class="glossarylink" href="../glossary.html#regex" title="see glossary">regular expression</a>
2954 as an argument instead of a simple string. For example:</p>
2956 <pre class="prettyprint lang-config"><LocationMatch "/(extra|special)/data">
2958 </LocationMatch></pre>
2961 <p>would match URLs that contained the substring <code>/extra/data</code>
2962 or <code>/special/data</code>.</p>
2964 <div class="note"><p>If the intent is that a URL <strong>starts with</strong>
2965 <code>/extra/data</code>, rather than merely
2966 <strong>contains</strong> <code>/extra/data</code>, prefix the
2967 regular expression with a <code>^</code> to require this.</p>
2969 <pre class="prettyprint lang-config"><LocationMatch "^/(extra|special)/data"></pre>
2973 <p>From 2.4.8 onwards, named groups and backreferences are captured and
2974 written to the environment with the corresponding name prefixed with
2975 "MATCH_" and in upper case. This allows elements of URLs to be referenced
2976 from within <a href="../expr.html">expressions</a> and modules like
2977 <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>. In order to prevent confusion, numbered
2978 (unnamed) backreferences are ignored. Use named groups instead.</p>
2980 <pre class="prettyprint lang-config"><LocationMatch "^/combined/(?<sitename>[^/]+)">
2981 require ldap-group cn=%{env:MATCH_SITENAME},ou=combined,o=Example
2982 </LocationMatch></pre>
2987 <li><a href="../sections.html">How <Directory>, <Location>
2988 and <Files> sections work</a> for an explanation of how these
2989 different sections are combined when a request is received</li>
2992 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
2993 <div class="directive-section"><h2><a name="LogLevel" id="LogLevel">LogLevel</a> <a name="loglevel" id="loglevel">Directive</a></h2>
2994 <table class="directive">
2995 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls the verbosity of the ErrorLog</td></tr>
2996 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LogLevel [<var>module</var>:]<var>level</var>
2997 [<var>module</var>:<var>level</var>] ...
2999 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>LogLevel warn</code></td></tr>
3000 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3001 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3002 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3003 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Per-module and per-directory configuration is available in
3004 Apache HTTP Server 2.3.6 and later</td></tr>
3006 <p><code class="directive">LogLevel</code> adjusts the verbosity of the
3007 messages recorded in the error logs (see <code class="directive"><a href="#errorlog">ErrorLog</a></code> directive). The following
3008 <var>level</var>s are available, in order of decreasing
3011 <table class="bordered">
3014 <th><strong>Level</strong> </th>
3016 <th><strong>Description</strong> </th>
3018 <th><strong>Example</strong> </th>
3022 <td><code>emerg</code> </td>
3024 <td>Emergencies - system is unusable.</td>
3026 <td>"Child cannot open lock file. Exiting"</td>
3030 <td><code>alert</code> </td>
3032 <td>Action must be taken immediately.</td>
3034 <td>"getpwuid: couldn't determine user name from uid"</td>
3038 <td><code>crit</code> </td>
3040 <td>Critical Conditions.</td>
3042 <td>"socket: Failed to get a socket, exiting child"</td>
3046 <td><code>error</code> </td>
3048 <td>Error conditions.</td>
3050 <td>"Premature end of script headers"</td>
3054 <td><code>warn</code> </td>
3056 <td>Warning conditions.</td>
3058 <td>"child process 1234 did not exit, sending another
3063 <td><code>notice</code> </td>
3065 <td>Normal but significant condition.</td>
3067 <td>"httpd: caught SIGBUS, attempting to dump core in
3072 <td><code>info</code> </td>
3074 <td>Informational.</td>
3076 <td>"Server seems busy, (you may need to increase
3077 StartServers, or Min/MaxSpareServers)..."</td>
3081 <td><code>debug</code> </td>
3083 <td>Debug-level messages</td>
3085 <td>"Opening config file ..."</td>
3088 <td><code>trace1</code> </td>
3090 <td>Trace messages</td>
3092 <td>"proxy: FTP: control connection complete"</td>
3095 <td><code>trace2</code> </td>
3097 <td>Trace messages</td>
3099 <td>"proxy: CONNECT: sending the CONNECT request to the remote proxy"</td>
3102 <td><code>trace3</code> </td>
3104 <td>Trace messages</td>
3106 <td>"openssl: Handshake: start"</td>
3109 <td><code>trace4</code> </td>
3111 <td>Trace messages</td>
3113 <td>"read from buffered SSL brigade, mode 0, 17 bytes"</td>
3116 <td><code>trace5</code> </td>
3118 <td>Trace messages</td>
3120 <td>"map lookup FAILED: map=rewritemap key=keyname"</td>
3123 <td><code>trace6</code> </td>
3125 <td>Trace messages</td>
3127 <td>"cache lookup FAILED, forcing new map lookup"</td>
3130 <td><code>trace7</code> </td>
3132 <td>Trace messages, dumping large amounts of data</td>
3134 <td>"| 0000: 02 23 44 30 13 40 ac 34 df 3d bf 9a 19 49 39 15 |"</td>
3137 <td><code>trace8</code> </td>
3139 <td>Trace messages, dumping large amounts of data</td>
3141 <td>"| 0000: 02 23 44 30 13 40 ac 34 df 3d bf 9a 19 49 39 15 |"</td>
3145 <p>When a particular level is specified, messages from all
3146 other levels of higher significance will be reported as well.
3147 <em>E.g.</em>, when <code>LogLevel info</code> is specified,
3148 then messages with log levels of <code>notice</code> and
3149 <code>warn</code> will also be posted.</p>
3151 <p>Using a level of at least <code>crit</code> is
3156 <pre class="prettyprint lang-config">LogLevel notice</pre>
3159 <div class="note"><h3>Note</h3>
3160 <p>When logging to a regular file, messages of the level
3161 <code>notice</code> cannot be suppressed and thus are always
3162 logged. However, this doesn't apply when logging is done
3163 using <code>syslog</code>.</p>
3166 <p>Specifying a level without a module name will reset the level
3167 for all modules to that level. Specifying a level with a module
3168 name will set the level for that module only. It is possible to
3169 use the module source file name, the module identifier, or the
3170 module identifier with the trailing <code>_module</code> omitted
3171 as module specification. This means the following three specifications
3174 <pre class="prettyprint lang-config">LogLevel info ssl:warn
3175 LogLevel info mod_ssl.c:warn
3176 LogLevel info ssl_module:warn</pre>
3179 <p>It is also possible to change the level per directory:</p>
3181 <pre class="prettyprint lang-config">LogLevel info
3182 <Directory "/usr/local/apache/htdocs/app">
3184 </Directory></pre>
3188 Per directory loglevel configuration only affects messages that are
3189 logged after the request has been parsed and that are associated with
3190 the request. Log messages which are associated with the server or
3191 the connection are not affected. The latter can be influenced by the
3192 <code class="directive"><a href="#logleveloverride">LogLevelOverride</a></code> directive,
3198 <li><code class="directive"><a href="#errorlog">ErrorLog</a></code></li>
3199 <li><code class="directive"><a href="#errorlogformat">ErrorLogFormat</a></code></li>
3200 <li><code class="directive"><a href="#logleveloverride">LogLevelOverride</a></code></li>
3201 <li><a href="../logs.html">Apache HTTP Server Log Files</a></li>
3204 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3205 <div class="directive-section"><h2><a name="LogLevelOverride" id="LogLevelOverride">LogLevelOverride</a> <a name="logleveloverride" id="logleveloverride">Directive</a></h2>
3206 <table class="directive">
3207 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Override the verbosity of the ErrorLog for certain clients</td></tr>
3208 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LogLevel <var>ipaddress</var>[/<var>prefixlen</var>]
3209 [<var>module</var>:]<var>level</var> [<var>module</var>:<var>level</var>] ...
3211 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>unset</code></td></tr>
3212 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3213 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3214 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3215 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.5.0 and later</td></tr>
3217 <p><code class="directive">LogLevelOverride</code> adjusts the
3218 <code class="directive"><a href="#loglevel">LogLevel</a></code> for requests coming from
3219 certain client IP addresses.
3220 This allows to enable verbose logging only for certain test clients.
3221 The IP address is checked at a very early state in the connection
3222 processing. Therefore, <code class="directive">LogLevelOverride</code> allows to
3223 change the log level for things like the SSL handshake which happen before
3224 a <code class="directive"><a href="#loglevel">LogLevel</a></code> directive in an
3225 <code class="directive"><a href="#if"><If></a></code> container would
3228 <p><code class="directive">LogLevelOverride</code> accepts either a single
3229 IP-address or a CIDR IP-address/len subnet specification.
3230 For the syntax of the loglevel specification, see the
3231 <code class="directive"><a href="#loglevel">LogLevel</a></code> directive.</p>
3233 <p>For requests that match a <code class="directive">LogLevelOverride</code>
3234 directive, per-directory specifications of
3235 <code class="directive"><a href="#loglevel">LogLevel</a></code> are ignored.</p>
3239 <pre class="prettyprint lang-config"> LogLevelOverride 192.0.2.0/24 ssl:trace6
3240 LogLevelOverride 192.0.2.7 ssl:trace8</pre>
3244 <code class="directive">LogLevelOverride</code> only affects
3245 log messages that are associated with the request or the connection.
3246 Log messages which are associated with the server are not affected.
3252 <li><code class="directive"><a href="#loglevel">LogLevel</a></code></li>
3255 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3256 <div class="directive-section"><h2><a name="MaxKeepAliveRequests" id="MaxKeepAliveRequests">MaxKeepAliveRequests</a> <a name="maxkeepaliverequests" id="maxkeepaliverequests">Directive</a></h2>
3257 <table class="directive">
3258 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of requests allowed on a persistent
3259 connection</td></tr>
3260 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxKeepAliveRequests <var>number</var></code></td></tr>
3261 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxKeepAliveRequests 100</code></td></tr>
3262 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3263 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3264 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3266 <p>The <code class="directive">MaxKeepAliveRequests</code> directive
3267 limits the number of requests allowed per connection when
3268 <code class="directive"><a href="#keepalive">KeepAlive</a></code> is on. If it is
3269 set to <code>0</code>, unlimited requests will be allowed. We
3270 recommend that this setting be kept to a high value for maximum
3271 server performance.</p>
3275 <pre class="prettyprint lang-config">MaxKeepAliveRequests 500</pre>
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="MaxRangeOverlaps" id="MaxRangeOverlaps">MaxRangeOverlaps</a> <a name="maxrangeoverlaps" id="maxrangeoverlaps">Directive</a></h2>
3281 <table class="directive">
3282 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of overlapping ranges (eg: <code>100-200,150-300</code>) allowed before returning the complete
3284 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxRangeOverlaps default | unlimited | none | <var>number-of-ranges</var></code></td></tr>
3285 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxRangeOverlaps 20</code></td></tr>
3286 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3287 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3288 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3289 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.15 and later</td></tr>
3291 <p>The <code class="directive">MaxRangeOverlaps</code> directive
3292 limits the number of overlapping HTTP ranges the server is willing to
3293 return to the client. If more overlapping ranges than permitted are requested,
3294 the complete resource is returned instead.</p>
3297 <dt><strong>default</strong></dt>
3298 <dd>Limits the number of overlapping ranges to a compile-time default of 20.</dd>
3300 <dt><strong>none</strong></dt>
3301 <dd>No overlapping Range headers are allowed.</dd>
3303 <dt><strong>unlimited</strong></dt>
3304 <dd>The server does not limit the number of overlapping ranges it is
3305 willing to satisfy.</dd>
3307 <dt><var>number-of-ranges</var></dt>
3308 <dd>A positive number representing the maximum number of overlapping ranges the
3309 server is willing to satisfy.</dd>
3313 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3314 <div class="directive-section"><h2><a name="MaxRangeReversals" id="MaxRangeReversals">MaxRangeReversals</a> <a name="maxrangereversals" id="maxrangereversals">Directive</a></h2>
3315 <table class="directive">
3316 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of range reversals (eg: <code>100-200,50-70</code>) allowed before returning the complete
3318 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxRangeReversals default | unlimited | none | <var>number-of-ranges</var></code></td></tr>
3319 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxRangeReversals 20</code></td></tr>
3320 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3321 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3322 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3323 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.15 and later</td></tr>
3325 <p>The <code class="directive">MaxRangeReversals</code> directive
3326 limits the number of HTTP Range reversals the server is willing to
3327 return to the client. If more ranges reversals than permitted are requested,
3328 the complete resource is returned instead.</p>
3331 <dt><strong>default</strong></dt>
3332 <dd>Limits the number of range reversals to a compile-time default of 20.</dd>
3334 <dt><strong>none</strong></dt>
3335 <dd>No Range reversals headers are allowed.</dd>
3337 <dt><strong>unlimited</strong></dt>
3338 <dd>The server does not limit the number of range reversals it is
3339 willing to satisfy.</dd>
3341 <dt><var>number-of-ranges</var></dt>
3342 <dd>A positive number representing the maximum number of range reversals the
3343 server is willing to satisfy.</dd>
3347 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3348 <div class="directive-section"><h2><a name="MaxRanges" id="MaxRanges">MaxRanges</a> <a name="maxranges" id="maxranges">Directive</a></h2>
3349 <table class="directive">
3350 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Number of ranges allowed before returning the complete
3352 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MaxRanges default | unlimited | none | <var>number-of-ranges</var></code></td></tr>
3353 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MaxRanges 200</code></td></tr>
3354 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3355 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3356 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3357 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.15 and later</td></tr>
3359 <p>The <code class="directive">MaxRanges</code> directive
3360 limits the number of HTTP ranges the server is willing to
3361 return to the client. If more ranges than permitted are requested,
3362 the complete resource is returned instead.</p>
3365 <dt><strong>default</strong></dt>
3366 <dd>Limits the number of ranges to a compile-time default of 200.</dd>
3368 <dt><strong>none</strong></dt>
3369 <dd>Range headers are ignored.</dd>
3371 <dt><strong>unlimited</strong></dt>
3372 <dd>The server does not limit the number of ranges it is
3373 willing to satisfy.</dd>
3375 <dt><var>number-of-ranges</var></dt>
3376 <dd>A positive number representing the maximum number of ranges the
3377 server is willing to satisfy.</dd>
3381 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3382 <div class="directive-section"><h2><a name="MergeTrailers" id="MergeTrailers">MergeTrailers</a> <a name="mergetrailers" id="mergetrailers">Directive</a></h2>
3383 <table class="directive">
3384 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines whether trailers are merged into headers</td></tr>
3385 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MergeTrailers [on|off]</code></td></tr>
3386 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MergeTrailers off</code></td></tr>
3387 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3388 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3389 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3390 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.4.11 and later</td></tr>
3392 <p>This directive controls whether HTTP trailers are copied into the
3393 internal representation of HTTP headers. This merging occurs when the
3394 request body has been completely consumed, long after most header
3395 processing would have a chance to examine or modify request headers.</p>
3396 <p>This option is provided for compatibility with releases prior to 2.4.11,
3397 where trailers were always merged.</p>
3400 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3401 <div class="directive-section"><h2><a name="Mutex" id="Mutex">Mutex</a> <a name="mutex" id="mutex">Directive</a></h2>
3402 <table class="directive">
3403 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures mutex mechanism and lock file directory for all
3404 or specified mutexes</td></tr>
3405 <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>
3406 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Mutex default</code></td></tr>
3407 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3408 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3409 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3410 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache HTTP Server 2.3.4 and later</td></tr>
3412 <p>The <code class="directive">Mutex</code> directive sets the mechanism,
3413 and optionally the lock file location, that httpd and modules use
3414 to serialize access to resources. Specify <code>default</code> as
3415 the second argument to change the settings for all mutexes; specify
3416 a mutex name (see table below) as the second argument to override
3417 defaults only for that mutex.</p>
3419 <p>The <code class="directive">Mutex</code> directive is typically used in
3420 the following exceptional situations:</p>
3423 <li>change the mutex mechanism when the default mechanism selected
3424 by <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a> has a functional or performance
3427 <li>change the directory used by file-based mutexes when the
3428 default directory does not support locking</li>
3431 <div class="note"><h3>Supported modules</h3>
3432 <p>This directive only configures mutexes which have been registered
3433 with the core server using the <code>ap_mutex_register()</code> API.
3434 All modules bundled with httpd support the <code class="directive">Mutex</code>
3435 directive, but third-party modules may not. Consult the documentation
3436 of the third-party module, which must indicate the mutex name(s) which
3437 can be configured if this directive is supported.</p>
3440 <p>The following mutex <em>mechanisms</em> are available:</p>
3442 <li><code>default | yes</code>
3443 <p>This selects the default locking implementation, as determined by
3444 <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a>. The default locking implementation can
3445 be displayed by running <code class="program"><a href="../programs/httpd.html">httpd</a></code> with the
3446 <code>-V</code> option.</p></li>
3448 <li><code>none | no</code>
3449 <p>This effectively disables the mutex, and is only allowed for a
3450 mutex if the module indicates that it is a valid choice. Consult the
3451 module documentation for more information.</p></li>
3453 <li><code>posixsem</code>
3454 <p>This is a mutex variant based on a Posix semaphore.</p>
3456 <div class="warning"><h3>Warning</h3>
3457 <p>The semaphore ownership is not recovered if a thread in the process
3458 holding the mutex segfaults, resulting in a hang of the web server.</p>
3462 <li><code>sysvsem</code>
3463 <p>This is a mutex variant based on a SystemV IPC semaphore.</p>
3465 <div class="warning"><h3>Warning</h3>
3466 <p>It is possible to "leak" SysV semaphores if processes crash
3467 before the semaphore is removed.</p>
3470 <div class="warning"><h3>Security</h3>
3471 <p>The semaphore API allows for a denial of service attack by any
3472 CGIs running under the same uid as the webserver (<em>i.e.</em>,
3473 all CGIs, unless you use something like <code class="program"><a href="../programs/suexec.html">suexec</a></code>
3474 or <code>cgiwrapper</code>).</p>
3478 <li><code>sem</code>
3479 <p>This selects the "best" available semaphore implementation, choosing
3480 between Posix and SystemV IPC semaphores, in that order.</p></li>
3482 <li><code>pthread</code>
3483 <p>This is a mutex variant based on cross-process Posix thread
3486 <div class="warning"><h3>Warning</h3>
3487 <p>On most systems, if a child process terminates abnormally while
3488 holding a mutex that uses this implementation, the server will deadlock
3489 and stop responding to requests. When this occurs, the server will
3490 require a manual restart to recover.</p>
3491 <p>Solaris and Linux are notable exceptions as they provide a mechanism which
3492 usually allows the mutex to be recovered after a child process
3493 terminates abnormally while holding a mutex.</p>
3494 <p>If your system is POSIX compliant or if it implements the
3495 <code>pthread_mutexattr_setrobust_np()</code> function, you may be able
3496 to use the <code>pthread</code> option safely.</p>
3500 <li><code>fcntl:/path/to/mutex</code>
3501 <p>This is a mutex variant where a physical (lock-)file and the
3502 <code>fcntl()</code> function are used as the mutex.</p>
3504 <div class="warning"><h3>Warning</h3>
3505 <p>When multiple mutexes based on this mechanism are used within
3506 multi-threaded, multi-process environments, deadlock errors (EDEADLK)
3507 can be reported for valid mutex operations if <code>fcntl()</code>
3508 is not thread-aware, such as on Solaris.</p>
3512 <li><code>flock:/path/to/mutex</code>
3513 <p>This is similar to the <code>fcntl:/path/to/mutex</code> method
3514 with the exception that the <code>flock()</code> function is used to
3515 provide file locking.</p></li>
3517 <li><code>file:/path/to/mutex</code>
3518 <p>This selects the "best" available file locking implementation,
3519 choosing between <code>fcntl</code> and <code>flock</code>, in that
3523 <p>Most mechanisms are only available on selected platforms, where the
3524 underlying platform and <a class="glossarylink" href="../glossary.html#apr" title="see glossary">APR</a> support it. Mechanisms
3525 which aren't available on all platforms are <em>posixsem</em>,
3526 <em>sysvsem</em>, <em>sem</em>, <em>pthread</em>, <em>fcntl</em>,
3527 <em>flock</em>, and <em>file</em>.</p>
3529 <p>With the file-based mechanisms <em>fcntl</em> and <em>flock</em>,
3530 the path, if provided, is a directory where the lock file will be created.
3531 The default directory is httpd's run-time file directory,
3532 <code class="directive"><a href="#defaultruntimedir">DefaultRuntimeDir</a></code>. If a relative
3533 path is provided, it is relative to
3534 <code class="directive"><a href="#defaultruntimedir">DefaultRuntimeDir</a></code>. Always use a local
3535 disk filesystem for <code>/path/to/mutex</code> and never a directory residing
3536 on a NFS- or AFS-filesystem. The basename of the file will be the mutex
3537 type, an optional instance string provided by the module, and unless the
3538 <code>OmitPID</code> keyword is specified, the process id of the httpd
3539 parent process will be appended to make the file name unique, avoiding
3540 conflicts when multiple httpd instances share a lock file directory. For
3541 example, if the mutex name is <code>mpm-accept</code> and the lock file
3542 directory is <code>/var/httpd/locks</code>, the lock file name for the
3543 httpd instance with parent process id 12345 would be
3544 <code>/var/httpd/locks/mpm-accept.12345</code>.</p>
3546 <div class="warning"><h3>Security</h3>
3547 <p>It is best to <em>avoid</em> putting mutex files in a world-writable
3548 directory such as <code>/var/tmp</code> because someone could create
3549 a denial of service attack and prevent the server from starting by
3550 creating a lockfile with the same name as the one the server will try
3554 <p>The following table documents the names of mutexes used by httpd
3555 and bundled modules.</p>
3557 <table class="bordered"><tr class="header">
3560 <th>Protected resource</th>
3563 <td><code>mpm-accept</code></td>
3564 <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>
3565 <td>incoming connections, to avoid the thundering herd problem;
3566 for more information, refer to the
3567 <a href="../misc/perf-tuning.html">performance tuning</a>
3571 <td><code>authdigest-client</code></td>
3572 <td><code class="module"><a href="../mod/mod_auth_digest.html">mod_auth_digest</a></code></td>
3573 <td>client list in shared memory</td>
3576 <td><code>authdigest-opaque</code></td>
3577 <td><code class="module"><a href="../mod/mod_auth_digest.html">mod_auth_digest</a></code></td>
3578 <td>counter in shared memory</td>
3581 <td><code>ldap-cache</code></td>
3582 <td><code class="module"><a href="../mod/mod_ldap.html">mod_ldap</a></code></td>
3583 <td>LDAP result cache</td>
3586 <td><code>rewrite-map</code></td>
3587 <td><code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code></td>
3588 <td>communication with external mapping programs, to avoid
3589 intermixed I/O from multiple requests</td>
3592 <td><code>ssl-cache</code></td>
3593 <td><code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code></td>
3594 <td>SSL session cache</td>
3597 <td><code>ssl-stapling</code></td>
3598 <td><code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code></td>
3599 <td>OCSP stapling response cache</td>
3602 <td><code>watchdog-callback</code></td>
3603 <td><code class="module"><a href="../mod/mod_watchdog.html">mod_watchdog</a></code></td>
3604 <td>callback function of a particular client module</td>
3608 <p>The <code>OmitPID</code> keyword suppresses the addition of the httpd
3609 parent process id from the lock file name.</p>
3611 <p>In the following example, the mutex mechanism for the MPM accept
3612 mutex will be changed from the compiled-in default to <code>fcntl</code>,
3613 with the associated lock file created in directory
3614 <code>/var/httpd/locks</code>. The mutex mechanism for all other mutexes
3615 will be changed from the compiled-in default to <code>sysvsem</code>.</p>
3617 <pre class="prettyprint lang-config">Mutex sysvsem default
3618 Mutex fcntl:/var/httpd/locks mpm-accept</pre>
3622 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3623 <div class="directive-section"><h2><a name="NameVirtualHost" id="NameVirtualHost">NameVirtualHost</a> <a name="namevirtualhost" id="namevirtualhost">Directive</a></h2>
3624 <table class="directive">
3625 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>DEPRECATED: Designates an IP address for name-virtual
3627 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>NameVirtualHost <var>addr</var>[:<var>port</var>]</code></td></tr>
3628 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3629 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3630 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3633 <p>Prior to 2.3.11, <code class="directive">NameVirtualHost</code> was required
3634 to instruct the server that a particular IP address and port combination
3635 was usable as a name-based virtual host. In 2.3.11 and later,
3636 any time an IP address and port combination is used in multiple virtual
3637 hosts, name-based virtual hosting is automatically enabled for that address.</p>
3639 <p>This directive currently has no effect.</p>
3643 <li><a href="../vhosts/">Virtual Hosts
3644 documentation</a></li>
3647 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3648 <div class="directive-section"><h2><a name="Options" id="Options">Options</a> <a name="options" id="options">Directive</a></h2>
3649 <table class="directive">
3650 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures what features are available in a particular
3652 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Options
3653 [+|-]<var>option</var> [[+|-]<var>option</var>] ...</code></td></tr>
3654 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Options FollowSymlinks</code></td></tr>
3655 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3656 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>Options</td></tr>
3657 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3658 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3659 <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>
3661 <p>The <code class="directive">Options</code> directive controls which
3662 server features are available in a particular directory.</p>
3664 <p><var>option</var> can be set to <code>None</code>, in which
3665 case none of the extra features are enabled, or one or more of
3669 <dt><code>All</code></dt>
3671 <dd>All options except for <code>MultiViews</code>.</dd>
3673 <dt><code>ExecCGI</code></dt>
3676 Execution of CGI scripts using <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code>
3679 <dt><code>FollowSymLinks</code></dt>
3682 The server will follow symbolic links in this directory. This is
3683 the default setting.
3685 <p>Even though the server follows the symlink it does <em>not</em>
3686 change the pathname used to match against <code class="directive"><a href="#directory"><Directory></a></code> sections.</p>
3688 <p>The <code>FollowSymLinks</code> and
3689 <code>SymLinksIfOwnerMatch</code> <code class="directive"><a href="#options">Options</a></code> work only in <code class="directive"><a href="#directory"><Directory></a></code> sections or
3690 <code>.htaccess</code> files.</p>
3692 <p>Omitting this option should not be considered a security restriction,
3693 since symlink testing is subject to race conditions that make it
3697 <dt><code>Includes</code></dt>
3700 Server-side includes provided by <code class="module"><a href="../mod/mod_include.html">mod_include</a></code>
3703 <dt><code>IncludesNOEXEC</code></dt>
3707 Server-side includes are permitted, but the <code>#exec
3708 cmd</code> and <code>#exec cgi</code> are disabled. It is still
3709 possible to <code>#include virtual</code> CGI scripts from
3710 <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>ed
3713 <dt><code>Indexes</code></dt>
3716 If a URL which maps to a directory is requested and there
3717 is no <code class="directive"><a href="../mod/mod_dir.html#directoryindex">DirectoryIndex</a></code>
3718 (<em>e.g.</em>, <code>index.html</code>) in that directory, then
3719 <code class="module"><a href="../mod/mod_autoindex.html">mod_autoindex</a></code> will return a formatted listing
3720 of the directory.</dd>
3722 <dt><code>MultiViews</code></dt>
3725 <a href="../content-negotiation.html">Content negotiated</a>
3726 "MultiViews" are allowed using
3727 <code class="module"><a href="../mod/mod_negotiation.html">mod_negotiation</a></code>.
3728 <div class="note"><h3>Note</h3> <p>This option gets ignored if set
3729 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>
3730 needs real resources to compare against and evaluate from.</p></div>
3733 <dt><code>SymLinksIfOwnerMatch</code></dt>
3735 <dd>The server will only follow symbolic links for which the
3736 target file or directory is owned by the same user id as the
3739 <div class="note"><h3>Note</h3>
3740 <p>The <code>FollowSymLinks</code> and
3741 <code>SymLinksIfOwnerMatch</code> <code class="directive"><a href="#options">Options</a></code> work only in <code class="directive"><a href="#directory"><Directory></a></code> sections or
3742 <code>.htaccess</code> files.</p>
3744 <p>This option should not be considered a security restriction,
3745 since symlink testing is subject to race conditions that make it
3750 <p>Normally, if multiple <code class="directive">Options</code> could
3751 apply to a directory, then the most specific one is used and
3752 others are ignored; the options are not merged. (See <a href="../sections.html#merging">how sections are merged</a>.)
3753 However if <em>all</em> the options on the
3754 <code class="directive">Options</code> directive are preceded by a
3755 <code>+</code> or <code>-</code> symbol, the options are
3756 merged. Any options preceded by a <code>+</code> are added to the
3757 options currently in force, and any options preceded by a
3758 <code>-</code> are removed from the options currently in
3761 <div class="note"><h3>Note</h3>
3762 <p>Mixing <code class="directive">Options</code> with a <code>+</code> or
3763 <code>-</code> with those without is not valid syntax and will be
3764 rejected during server startup by the syntax check with an abort.</p>
3767 <p>For example, without any <code>+</code> and <code>-</code> symbols:</p>
3769 <pre class="prettyprint lang-config"><Directory "/web/docs">
3770 Options Indexes FollowSymLinks
3773 <Directory "/web/docs/spec">
3775 </Directory></pre>
3778 <p>then only <code>Includes</code> will be set for the
3779 <code>/web/docs/spec</code> directory. However if the second
3780 <code class="directive">Options</code> directive uses the <code>+</code> and
3781 <code>-</code> symbols:</p>
3783 <pre class="prettyprint lang-config"><Directory "/web/docs">
3784 Options Indexes FollowSymLinks
3787 <Directory "/web/docs/spec">
3788 Options +Includes -Indexes
3789 </Directory></pre>
3792 <p>then the options <code>FollowSymLinks</code> and
3793 <code>Includes</code> are set for the <code>/web/docs/spec</code>
3796 <div class="note"><h3>Note</h3>
3797 <p>Using <code>-IncludesNOEXEC</code> or
3798 <code>-Includes</code> disables server-side includes completely
3799 regardless of the previous setting.</p>
3802 <p>The default in the absence of any other settings is
3803 <code>FollowSymlinks</code>.</p>
3806 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3807 <div class="directive-section"><h2><a name="Protocol" id="Protocol">Protocol</a> <a name="protocol" id="protocol">Directive</a></h2>
3808 <table class="directive">
3809 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Protocol for a listening socket</td></tr>
3810 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Protocol <var>protocol</var></code></td></tr>
3811 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3812 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3813 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3814 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>On Windows, only available from Apache 2.3.3 and later.</td></tr>
3816 <p>This directive specifies the protocol used for a specific listening socket.
3817 The protocol is used to determine which module should handle a request and
3818 to apply protocol specific optimizations with the <code class="directive">AcceptFilter</code>
3821 <p>You only need to set the protocol if you are running on non-standard ports;
3822 otherwise, <code>http</code> is assumed for port 80 and <code>https</code>
3825 <p>For example, if you are running <code>https</code> on a non-standard port,
3826 specify the protocol explicitly:</p>
3828 <pre class="prettyprint lang-config">Protocol https</pre>
3831 <p>You can also specify the protocol using the <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code> directive.</p>
3835 <li><code class="directive"><a href="#acceptfilter">AcceptFilter</a></code></li>
3836 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
3839 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3840 <div class="directive-section"><h2><a name="Protocols" id="Protocols">Protocols</a> <a name="protocols" id="protocols">Directive</a></h2>
3841 <table class="directive">
3842 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Protocols available for a server/virtual host</td></tr>
3843 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Protocols <var>protocol</var> ...</code></td></tr>
3844 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Protocols http/1.1</code></td></tr>
3845 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</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>
3848 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Only available from Apache 2.4.17 and later.</td></tr>
3850 <p>This directive specifies the list of protocols supported for a
3851 server/virtual host. The list determines the allowed protocols
3852 a client may negotiate for this server/host.</p>
3854 <p>You need to set protocols if you want to extend the available
3855 protocols for a server/host. By default, only the http/1.1 protocol
3856 (which includes the compatibility with 1.0 and 0.9 clients) is
3859 <p>For example, if you want to support HTTP/2 for a server with TLS,
3862 <pre class="prettyprint lang-config">Protocols h2 http/1.1</pre>
3865 <p>Valid protocols are <code>http/1.1</code> for http and https connections,
3866 <code>h2</code> on https connections and <code>h2c</code> for http
3867 connections. Modules may enable more protocols.</p>
3869 <p>It is safe to specify protocols that are unavailable/disabled. Such
3870 protocol names will simply be ignored.</p>
3872 <p>Protocols specified in base servers are inherited for virtual hosts
3873 only if the virtual host has no own Protocols directive. Or, the other
3874 way around, Protocols directives in virtual hosts replace any
3875 such directive in the base server.
3881 <li><code class="directive"><a href="#protocolshonororder">ProtocolsHonorOrder</a></code></li>
3884 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3885 <div class="directive-section"><h2><a name="ProtocolsHonorOrder" id="ProtocolsHonorOrder">ProtocolsHonorOrder</a> <a name="protocolshonororder" id="protocolshonororder">Directive</a></h2>
3886 <table class="directive">
3887 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines if order of Protocols determines precedence during negotiation</td></tr>
3888 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ProtocolsHonorOrder On|Off</code></td></tr>
3889 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ProtocolsHonorOrder On</code></td></tr>
3890 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
3891 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3892 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3893 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Only available from Apache 2.4.17 and later.</td></tr>
3895 <p>This directive specifies if the server should honor the order in which
3896 the <code class="directive">Protocols</code> directive lists protocols.</p>
3898 <p>If configured Off, the client supplied list order of protocols has
3899 precedence over the order in the server configuration.</p>
3901 <p>With <code class="directive">ProtocolsHonorOrder</code> set to <code>on</code>
3902 (default), the client ordering does not matter and only the ordering
3903 in the server settings influences the outcome of the protocol
3909 <li><code class="directive"><a href="#protocols">Protocols</a></code></li>
3912 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3913 <div class="directive-section"><h2><a name="QualifyRedirectURL" id="QualifyRedirectURL">QualifyRedirectURL</a> <a name="qualifyredirecturl" id="qualifyredirecturl">Directive</a></h2>
3914 <table class="directive">
3915 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Controls whether the REDIRECT_URL environment variable is
3916 fully qualified</td></tr>
3917 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>QualifyRedirectURL ON|OFF</code></td></tr>
3918 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>QualifyRedirectURL OFF</code></td></tr>
3919 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
3920 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
3921 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3922 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3923 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Directive supported in 2.4.18 and later. 2.4.17 acted
3924 as if 'QualifyRedirectURL ON' was configured.</td></tr>
3926 <p>This directive controls whether the server will ensure that the
3927 REDIRECT_URL environment variable is fully qualified. By default,
3928 the variable contains the verbatim URL requested by the client,
3929 such as "/index.html". With <code class="directive"><a href="#qualifyredirecturl on">QualifyRedirectURL ON</a></code>, the same request would result in a
3930 value such as "http://www.example.com/index.html".</p>
3931 <p>Even without this directive set, when a request is issued against a
3932 fully qualified URL, REDIRECT_URL will remain fully qualified.
3936 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3937 <div class="directive-section"><h2><a name="RegisterHttpMethod" id="RegisterHttpMethod">RegisterHttpMethod</a> <a name="registerhttpmethod" id="registerhttpmethod">Directive</a></h2>
3938 <table class="directive">
3939 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Register non-standard HTTP methods</td></tr>
3940 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>RegisterHttpMethod <var>method</var> [<var>method</var> [...]]</code></td></tr>
3941 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
3942 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3943 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3945 <p>HTTP Methods that are not conforming to the relvant RFCs are normally
3946 rejected by request processing in Apache HTTPD. To avoid this, modules
3947 can register non-standard HTTP methods they support.
3948 The <code class="directive">RegisterHttpMethod</code> allows to register such
3949 methods manually. This can be useful if such methods are forwarded
3950 for external processing, e.g. to a CGI script.</p>
3953 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3954 <div class="directive-section"><h2><a name="RLimitCPU" id="RLimitCPU">RLimitCPU</a> <a name="rlimitcpu" id="rlimitcpu">Directive</a></h2>
3955 <table class="directive">
3956 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the CPU consumption of processes launched
3957 by Apache httpd children</td></tr>
3958 <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>
3959 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
3960 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3961 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3962 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3963 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
3965 <p>Takes 1 or 2 parameters. The first parameter sets the soft
3966 resource limit for all processes and the second parameter sets
3967 the maximum resource limit. Either parameter can be a number,
3968 or <code>max</code> to indicate to the server that the limit should
3969 be set to the maximum allowed by the operating system
3970 configuration. Raising the maximum resource limit requires that
3971 the server is running as <code>root</code> or in the initial startup
3974 <p>This applies to processes forked from Apache httpd children
3975 servicing requests, not the Apache httpd children themselves. This
3976 includes CGI scripts and SSI exec commands, but not any
3977 processes forked from the Apache httpd parent, such as piped
3980 <p>CPU resource limits are expressed in seconds per
3985 <li><code class="directive"><a href="#rlimitmem">RLimitMEM</a></code></li>
3986 <li><code class="directive"><a href="#rlimitnproc">RLimitNPROC</a></code></li>
3989 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
3990 <div class="directive-section"><h2><a name="RLimitMEM" id="RLimitMEM">RLimitMEM</a> <a name="rlimitmem" id="rlimitmem">Directive</a></h2>
3991 <table class="directive">
3992 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the memory consumption of processes launched
3993 by Apache httpd children</td></tr>
3994 <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>
3995 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
3996 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
3997 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
3998 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
3999 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4001 <p>Takes 1 or 2 parameters. The first parameter sets the soft
4002 resource limit for all processes and the second parameter sets
4003 the maximum resource limit. Either parameter can be a number,
4004 or <code>max</code> to indicate to the server that the limit should
4005 be set to the maximum allowed by the operating system
4006 configuration. Raising the maximum resource limit requires that
4007 the server is running as <code>root</code> or in the initial startup
4010 <p>This applies to processes forked from Apache httpd children
4011 servicing requests, not the Apache httpd children themselves. This
4012 includes CGI scripts and SSI exec commands, but not any
4013 processes forked from the Apache httpd parent, such as piped
4016 <p>Memory resource limits are expressed in bytes per
4021 <li><code class="directive"><a href="#rlimitcpu">RLimitCPU</a></code></li>
4022 <li><code class="directive"><a href="#rlimitnproc">RLimitNPROC</a></code></li>
4025 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4026 <div class="directive-section"><h2><a name="RLimitNPROC" id="RLimitNPROC">RLimitNPROC</a> <a name="rlimitnproc" id="rlimitnproc">Directive</a></h2>
4027 <table class="directive">
4028 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Limits the number of processes that can be launched by
4029 processes launched by Apache httpd children</td></tr>
4030 <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>
4031 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>Unset; uses operating system defaults</code></td></tr>
4032 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4033 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
4034 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4035 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4037 <p>Takes 1 or 2 parameters. The first parameter sets the soft
4038 resource limit for all processes, and the second parameter sets
4039 the maximum resource limit. Either parameter can be a number,
4040 or <code>max</code> to indicate to the server that the limit
4041 should be set to the maximum allowed by the operating system
4042 configuration. Raising the maximum resource limit requires that
4043 the server is running as <code>root</code> or in the initial startup
4046 <p>This applies to processes forked from Apache httpd children
4047 servicing requests, not the Apache httpd children themselves. This
4048 includes CGI scripts and SSI exec commands, but not any
4049 processes forked from the Apache httpd parent, such as piped
4052 <p>Process limits control the number of processes per user.</p>
4054 <div class="note"><h3>Note</h3>
4055 <p>If CGI processes are <strong>not</strong> running
4056 under user ids other than the web server user id, this directive
4057 will limit the number of processes that the server itself can
4058 create. Evidence of this situation will be indicated by
4059 <strong><code>cannot fork</code></strong> messages in the
4060 <code>error_log</code>.</p>
4065 <li><code class="directive"><a href="#rlimitmem">RLimitMEM</a></code></li>
4066 <li><code class="directive"><a href="#rlimitcpu">RLimitCPU</a></code></li>
4069 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4070 <div class="directive-section"><h2><a name="ScriptInterpreterSource" id="ScriptInterpreterSource">ScriptInterpreterSource</a> <a name="scriptinterpretersource" id="scriptinterpretersource">Directive</a></h2>
4071 <table class="directive">
4072 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Technique for locating the interpreter for CGI
4074 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ScriptInterpreterSource Registry|Registry-Strict|Script</code></td></tr>
4075 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ScriptInterpreterSource Script</code></td></tr>
4076 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4077 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4078 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4079 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4080 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Win32 only.</td></tr>
4082 <p>This directive is used to control how Apache httpd finds the
4083 interpreter used to run CGI scripts. The default setting is
4084 <code>Script</code>. This causes Apache httpd to use the interpreter pointed to
4085 by the shebang line (first line, starting with <code>#!</code>) in the
4086 script. On Win32 systems this line usually looks like:</p>
4088 <pre class="prettyprint lang-perl">#!C:/Perl/bin/perl.exe</pre>
4091 <p>or, if <code>perl</code> is in the <code>PATH</code>, simply:</p>
4093 <pre class="prettyprint lang-perl">#!perl</pre>
4096 <p>Setting <code>ScriptInterpreterSource Registry</code> will
4097 cause the Windows Registry tree <code>HKEY_CLASSES_ROOT</code> to be
4098 searched using the script file extension (e.g., <code>.pl</code>) as a
4099 search key. The command defined by the registry subkey
4100 <code>Shell\ExecCGI\Command</code> or, if it does not exist, by the subkey
4101 <code>Shell\Open\Command</code> is used to open the script file. If the
4102 registry keys cannot be found, Apache httpd falls back to the behavior of the
4103 <code>Script</code> option.</p>
4105 <div class="warning"><h3>Security</h3>
4106 <p>Be careful when using <code>ScriptInterpreterSource
4107 Registry</code> with <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>'ed directories, because
4108 Apache httpd will try to execute <strong>every</strong> file within this
4109 directory. The <code>Registry</code> setting may cause undesired
4110 program calls on files which are typically not executed. For
4111 example, the default open command on <code>.htm</code> files on
4112 most Windows systems will execute Microsoft Internet Explorer, so
4113 any HTTP request for an <code>.htm</code> file existing within the
4114 script directory would start the browser in the background on the
4115 server. This is a good way to crash your system within a minute or
4119 <p>The option <code>Registry-Strict</code> which is new in Apache HTTP Server
4120 2.0 does the same thing as <code>Registry</code> but uses only the
4121 subkey <code>Shell\ExecCGI\Command</code>. The
4122 <code>ExecCGI</code> key is not a common one. It must be
4123 configured manually in the windows registry and hence prevents
4124 accidental program calls on your system.</p>
4127 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4128 <div class="directive-section"><h2><a name="SeeRequestTail" id="SeeRequestTail">SeeRequestTail</a> <a name="seerequesttail" id="seerequesttail">Directive</a></h2>
4129 <table class="directive">
4130 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determine if mod_status displays the first 63 characters
4131 of a request or the last 63, assuming the request itself is greater than
4133 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SeeRequestTail On|Off</code></td></tr>
4134 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SeeRequestTail Off</code></td></tr>
4135 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4136 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4137 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4139 <p>mod_status with <code>ExtendedStatus On</code>
4140 displays the actual request being handled.
4141 For historical purposes, only 63 characters of the request
4142 are actually stored for display purposes. This directive
4143 controls whether the 1st 63 characters are stored (the previous
4144 behavior and the default) or if the last 63 characters are. This
4145 is only applicable, of course, if the length of the request is
4146 64 characters or greater.</p>
4148 <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:
4151 <table class="bordered">
4153 <th>Off (default)</th>
4154 <td>GET /disk1/storage/apache/htdocs/images/imagestore1/food/apples</td>
4158 <td>orage/apache/htdocs/images/imagestore1/food/apples.jpg HTTP/1.1</td>
4164 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4165 <div class="directive-section"><h2><a name="ServerAdmin" id="ServerAdmin">ServerAdmin</a> <a name="serveradmin" id="serveradmin">Directive</a></h2>
4166 <table class="directive">
4167 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Email address that the server includes in error
4168 messages sent to the client</td></tr>
4169 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerAdmin <var>email-address</var>|<var>URL</var></code></td></tr>
4170 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4171 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4172 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4174 <p>The <code class="directive">ServerAdmin</code> sets the contact address
4175 that the server includes in any error messages it returns to the
4176 client. If the <code>httpd</code> doesn't recognize the supplied argument
4178 assumes, that it's an <var>email-address</var> and prepends it with
4179 <code>mailto:</code> in hyperlink targets. However, it's recommended to
4180 actually use an email address, since there are a lot of CGI scripts that
4181 make that assumption. If you want to use an URL, it should point to another
4182 server under your control. Otherwise users may not be able to contact you in
4185 <p>It may be worth setting up a dedicated address for this, e.g.</p>
4187 <pre class="prettyprint lang-config">ServerAdmin www-admin@foo.example.com</pre>
4189 <p>as users do not always mention that they are talking about the
4193 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4194 <div class="directive-section"><h2><a name="ServerAlias" id="ServerAlias">ServerAlias</a> <a name="serveralias" id="serveralias">Directive</a></h2>
4195 <table class="directive">
4196 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Alternate names for a host used when matching requests
4197 to name-virtual hosts</td></tr>
4198 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerAlias <var>hostname</var> [<var>hostname</var>] ...</code></td></tr>
4199 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>virtual host</td></tr>
4200 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4201 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4203 <p>The <code class="directive">ServerAlias</code> directive sets the
4204 alternate names for a host, for use with <a href="../vhosts/name-based.html">name-based virtual hosts</a>. The
4205 <code class="directive">ServerAlias</code> may include wildcards, if appropriate.</p>
4207 <pre class="prettyprint lang-config"><VirtualHost *:80>
4208 ServerName server.example.com
4209 ServerAlias server server2.example.com server2
4210 ServerAlias *.example.com
4211 UseCanonicalName Off
4213 </VirtualHost></pre>
4216 <p>Name-based virtual hosts for the best-matching set of <code class="directive"><a href="#virtualhost"><virtualhost></a></code>s are processed
4217 in the order they appear in the configuration. The first matching <code class="directive"><a href="#servername">ServerName</a></code> or <code class="directive"><a href="#serveralias">ServerAlias</a></code> is used, with no different precedence for wildcards
4218 (nor for ServerName vs. ServerAlias). </p>
4220 <p>The complete list of names in the <code class="directive"><a href="#virtualhost"><VirtualHost></a></code>
4221 directive are treated just like a (non wildcard)
4222 <code class="directive">ServerAlias</code>.</p>
4227 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
4228 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
4231 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4232 <div class="directive-section"><h2><a name="ServerName" id="ServerName">ServerName</a> <a name="servername" id="servername">Directive</a></h2>
4233 <table class="directive">
4234 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Hostname and port that the server uses to identify
4236 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerName [<var>scheme</var>://]<var>domain-name</var>|<var>ip-address</var>[:<var>port</var>]</code></td></tr>
4237 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4238 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4239 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4241 <p>The <code class="directive">ServerName</code> directive sets the
4242 request scheme, hostname and port that the server uses to identify itself.
4245 <p><code class="directive">ServerName</code> is used (possibly
4246 in conjunction with <code class="directive"><a href="#serveralias">ServerAlias</a></code>) to uniquely
4247 identify a virtual host, when using <a href="../vhosts/name-based.html">name-based virtual hosts</a>.</p>
4249 <p>Additionally, this is used when
4250 creating self-referential redirection URLs when
4251 <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> is set to a non-default
4254 <p>For example, if the name of the
4255 machine hosting the web server is <code>simple.example.com</code>,
4256 but the machine also has the DNS alias <code>www.example.com</code>
4257 and you wish the web server to be so identified, the following
4258 directive should be used:</p>
4260 <pre class="prettyprint lang-config">ServerName www.example.com</pre>
4263 <p>The <code class="directive">ServerName</code> directive
4264 may appear anywhere within the definition of a server. However,
4265 each appearance overrides the previous appearance (within that
4268 <p>If no <code class="directive">ServerName</code> is specified, the
4269 server attempts to deduce the client visible hostname by first asking
4270 the operating system for the system hostname, and if that fails,
4271 performing a reverse lookup on an IP address present on the system.</p>
4273 <p>If no port is specified in the
4274 <code class="directive">ServerName</code>, then the server will use the
4275 port from the incoming request. For optimal reliability and
4276 predictability, you should specify an explicit hostname and port
4277 using the <code class="directive">ServerName</code> directive.</p>
4279 <p>If you are using <a href="../vhosts/name-based.html">name-based virtual hosts</a>,
4280 the <code class="directive">ServerName</code> inside a
4281 <code class="directive"><a href="#virtualhost"><VirtualHost></a></code>
4282 section specifies what hostname must appear in the request's
4283 <code>Host:</code> header to match this virtual host.</p>
4285 <p>Sometimes, the server runs behind a device that processes SSL,
4286 such as a reverse proxy, load balancer or SSL offload
4287 appliance. When this is the case, specify the
4288 <code>https://</code> scheme and the port number to which the
4289 clients connect in the <code class="directive">ServerName</code> directive
4290 to make sure that the server generates the correct
4291 self-referential URLs.
4294 <p>See the description of the
4295 <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> and
4296 <code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code> directives for
4297 settings which determine whether self-referential URLs (e.g., by the
4298 <code class="module"><a href="../mod/mod_dir.html">mod_dir</a></code> module) will refer to the
4299 specified port, or to the port number given in the client's request.
4302 <div class="warning">
4303 <p>Failure to set <code class="directive">ServerName</code> to a name that
4304 your server can resolve to an IP address will result in a startup
4305 warning. <code>httpd</code> will then use whatever hostname it can
4306 determine, using the system's <code>hostname</code> command. This
4307 will almost never be the hostname you actually want.</p>
4308 <div class="example"><p><code>
4309 httpd: Could not reliably determine the server's fully qualified domain name, using rocinante.local for ServerName
4316 <li><a href="../dns-caveats.html">Issues Regarding DNS and
4317 Apache HTTP Server</a></li>
4318 <li><a href="../vhosts/">Apache HTTP Server virtual host
4319 documentation</a></li>
4320 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
4321 <li><code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code></li>
4322 <li><code class="directive"><a href="#serveralias">ServerAlias</a></code></li>
4325 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4326 <div class="directive-section"><h2><a name="ServerPath" id="ServerPath">ServerPath</a> <a name="serverpath" id="serverpath">Directive</a></h2>
4327 <table class="directive">
4328 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Legacy URL pathname for a name-based virtual host that
4329 is accessed by an incompatible browser</td></tr>
4330 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerPath <var>URL-path</var></code></td></tr>
4331 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>virtual host</td></tr>
4332 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4333 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4335 <p>The <code class="directive">ServerPath</code> directive sets the legacy
4336 URL pathname for a host, for use with <a href="../vhosts/">name-based virtual hosts</a>.</p>
4340 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
4343 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4344 <div class="directive-section"><h2><a name="ServerRoot" id="ServerRoot">ServerRoot</a> <a name="serverroot" id="serverroot">Directive</a></h2>
4345 <table class="directive">
4346 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Base directory for the server installation</td></tr>
4347 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerRoot <var>directory-path</var></code></td></tr>
4348 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerRoot /usr/local/apache</code></td></tr>
4349 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4350 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4351 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4353 <p>The <code class="directive">ServerRoot</code> directive sets the
4354 directory in which the server lives. Typically it will contain the
4355 subdirectories <code>conf/</code> and <code>logs/</code>. Relative
4356 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
4357 relative to this directory.</p>
4359 <pre class="prettyprint lang-config">ServerRoot "/home/httpd"</pre>
4362 <p>The default location of <code class="directive">ServerRoot</code> may be
4363 modified by using the <code>--prefix</code> argument to
4364 <a href="../programs/configure.html"><code>configure</code></a>, and
4365 most third-party distributions of the server have a different
4366 default location from the one listed above.</p>
4371 <li><a href="../invoking.html">the <code>-d</code>
4372 option to <code>httpd</code></a></li>
4373 <li><a href="../misc/security_tips.html#serverroot">the
4374 security tips</a> for information on how to properly set
4375 permissions on the <code class="directive">ServerRoot</code></li>
4378 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4379 <div class="directive-section"><h2><a name="ServerSignature" id="ServerSignature">ServerSignature</a> <a name="serversignature" id="serversignature">Directive</a></h2>
4380 <table class="directive">
4381 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures the footer on server-generated documents</td></tr>
4382 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerSignature On|Off|EMail</code></td></tr>
4383 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerSignature Off</code></td></tr>
4384 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4385 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>All</td></tr>
4386 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4387 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4389 <p>The <code class="directive">ServerSignature</code> directive allows the
4390 configuration of a trailing footer line under server-generated
4391 documents (error messages, <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> ftp directory
4392 listings, <code class="module"><a href="../mod/mod_info.html">mod_info</a></code> output, ...). The reason why you
4393 would want to enable such a footer line is that in a chain of proxies,
4394 the user often has no possibility to tell which of the chained servers
4395 actually produced a returned error message.</p>
4397 <p>The <code>Off</code>
4398 setting, which is the default, suppresses the footer line (and is
4399 therefore compatible with the behavior of Apache-1.2 and
4400 below). The <code>On</code> setting simply adds a line with the
4401 server version number and <code class="directive"><a href="#servername">ServerName</a></code> of the serving virtual host,
4402 and the <code>EMail</code> setting additionally creates a
4403 "mailto:" reference to the <code class="directive"><a href="#serveradmin">ServerAdmin</a></code> of the referenced
4406 <p>After version 2.0.44, the details of the server version number
4407 presented are controlled by the <code class="directive"><a href="#servertokens">ServerTokens</a></code> directive.</p>
4411 <li><code class="directive"><a href="#servertokens">ServerTokens</a></code></li>
4414 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4415 <div class="directive-section"><h2><a name="ServerTokens" id="ServerTokens">ServerTokens</a> <a name="servertokens" id="servertokens">Directive</a></h2>
4416 <table class="directive">
4417 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures the <code>Server</code> HTTP response
4419 <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>
4420 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ServerTokens Full</code></td></tr>
4421 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4422 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4423 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4425 <p>This directive controls whether <code>Server</code> response
4426 header field which is sent back to clients includes a
4427 description of the generic OS-type of the server as well as
4428 information about compiled-in modules.</p>
4431 <dt><code>ServerTokens Full</code> (or not specified)</dt>
4433 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.4.2
4434 (Unix) PHP/4.2.2 MyMod/1.2</code></dd>
4436 <dt><code>ServerTokens Prod[uctOnly]</code></dt>
4438 <dd>Server sends (<em>e.g.</em>): <code>Server:
4441 <dt><code>ServerTokens Major</code></dt>
4443 <dd>Server sends (<em>e.g.</em>): <code>Server:
4444 Apache/2</code></dd>
4446 <dt><code>ServerTokens Minor</code></dt>
4448 <dd>Server sends (<em>e.g.</em>): <code>Server:
4449 Apache/2.4</code></dd>
4451 <dt><code>ServerTokens Min[imal]</code></dt>
4453 <dd>Server sends (<em>e.g.</em>): <code>Server:
4454 Apache/2.4.2</code></dd>
4456 <dt><code>ServerTokens OS</code></dt>
4458 <dd>Server sends (<em>e.g.</em>): <code>Server: Apache/2.4.2
4463 <p>This setting applies to the entire server, and cannot be
4464 enabled or disabled on a virtualhost-by-virtualhost basis.</p>
4466 <p>After version 2.0.44, this directive also controls the
4467 information presented by the <code class="directive"><a href="#serversignature">ServerSignature</a></code> directive.</p>
4469 <div class="note">Setting <code class="directive">ServerTokens</code> to less than
4470 <code>minimal</code> is not recommended because it makes it more
4471 difficult to debug interoperational problems. Also note that
4472 disabling the Server: header does nothing at all to make your
4473 server more secure. The idea of "security through obscurity"
4474 is a myth and leads to a false sense of safety.</div>
4478 <li><code class="directive"><a href="#serversignature">ServerSignature</a></code></li>
4481 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4482 <div class="directive-section"><h2><a name="SetHandler" id="SetHandler">SetHandler</a> <a name="sethandler" id="sethandler">Directive</a></h2>
4483 <table class="directive">
4484 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Forces all matching files to be processed by a
4486 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetHandler <var>handler-name</var>|none|<var>expression</var></code></td></tr>
4487 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4488 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4489 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4490 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4491 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.5 and later</td></tr>
4493 <p>When placed into an <code>.htaccess</code> file or a
4494 <code class="directive"><a href="#directory"><Directory></a></code> or
4495 <code class="directive"><a href="#location"><Location></a></code>
4496 section, this directive forces all matching files to be parsed
4497 through the <a href="../handler.html">handler</a> given by
4498 <var>handler-name</var>. For example, if you had a directory you
4499 wanted to be parsed entirely as imagemap rule files, regardless
4500 of extension, you might put the following into an
4501 <code>.htaccess</code> file in that directory:</p>
4503 <pre class="prettyprint lang-config">SetHandler imap-file</pre>
4506 <p>Another example: if you wanted to have the server display a
4507 status report whenever a URL of
4508 <code>http://servername/status</code> was called, you might put
4509 the following into <code>httpd.conf</code>:</p>
4511 <pre class="prettyprint lang-config"><Location "/status">
4512 SetHandler server-status
4513 </Location></pre>
4516 <p>You could also use this directive to configure a particular
4517 handler for files with a particular file extension. For example:</p>
4519 <pre class="prettyprint lang-config"><FilesMatch "\.php$">
4520 SetHandler application/x-httpd-php
4521 </FilesMatch></pre>
4524 <p>String-valued expressions can be used to reference per-request
4525 variables, including backreferences to named regular expressions:</p>
4527 <pre class="prettyprint lang-config"><LocationMatch ^/app/(?<sub>[^/]+)/>
4528 SetHandler "proxy:unix:/var/run/app_%{env:MATCH_sub}.sock|fcgi://localhost:8080"
4529 </LocationMatch></pre>
4532 <p>You can override an earlier defined <code class="directive">SetHandler</code>
4533 directive by using the value <code>None</code>.</p>
4535 <div class="note"><h3>Note</h3>
4536 <p>Because <code class="directive">SetHandler</code> overrides default handlers,
4537 normal behavior such as handling of URLs ending in a slash (/) as
4538 directories or index files is suppressed.</p></div>
4542 <li><code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code></li>
4545 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4546 <div class="directive-section"><h2><a name="SetInputFilter" id="SetInputFilter">SetInputFilter</a> <a name="setinputfilter" id="setinputfilter">Directive</a></h2>
4547 <table class="directive">
4548 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the filters that will process client requests and POST
4550 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetInputFilter <var>filter</var>[;<var>filter</var>...]</code></td></tr>
4551 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4552 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4553 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4554 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4556 <p>The <code class="directive">SetInputFilter</code> directive sets the
4557 filter or filters which will process client requests and POST
4558 input when they are received by the server. This is in addition to
4559 any filters defined elsewhere, including the
4560 <code class="directive"><a href="../mod/mod_mime.html#addinputfilter">AddInputFilter</a></code>
4563 <p>If more than one filter is specified, they must be separated
4564 by semicolons in the order in which they should process the
4569 <li><a href="../filter.html">Filters</a> documentation</li>
4572 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4573 <div class="directive-section"><h2><a name="SetOutputFilter" id="SetOutputFilter">SetOutputFilter</a> <a name="setoutputfilter" id="setoutputfilter">Directive</a></h2>
4574 <table class="directive">
4575 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the filters that will process responses from the
4577 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SetOutputFilter <var>filter</var>[;<var>filter</var>...]</code></td></tr>
4578 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4579 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
4580 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4581 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4583 <p>The <code class="directive">SetOutputFilter</code> directive sets the filters
4584 which will process responses from the server before they are
4585 sent to the client. This is in addition to any filters defined
4586 elsewhere, including the
4587 <code class="directive"><a href="../mod/mod_mime.html#addoutputfilter">AddOutputFilter</a></code>
4590 <p>For example, the following configuration will process all files
4591 in the <code>/www/data/</code> directory for server-side
4594 <pre class="prettyprint lang-config"><Directory "/www/data/">
4595 SetOutputFilter INCLUDES
4596 </Directory></pre>
4599 <p>If more than one filter is specified, they must be separated
4600 by semicolons in the order in which they should process the
4605 <li><a href="../filter.html">Filters</a> documentation</li>
4608 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4609 <div class="directive-section"><h2><a name="TimeOut" id="TimeOut">TimeOut</a> <a name="timeout" id="timeout">Directive</a></h2>
4610 <table class="directive">
4611 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Amount of time the server will wait for
4612 certain events before failing a request</td></tr>
4613 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>TimeOut <var>seconds</var></code></td></tr>
4614 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>TimeOut 60</code></td></tr>
4615 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4616 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4617 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4619 <p>The <code class="directive">TimeOut</code> directive defines the length
4620 of time Apache httpd will wait for I/O in various circumstances:</p>
4623 <li><p>When reading data from the client, the length of time to
4624 wait for a TCP packet to arrive if the read buffer is
4626 <p> For initial data on a new connection, this directive doesn't
4627 take effect until after any configured <code class="directive"><a href="#acceptfilter">
4628 AcceptFilter</a></code> has passed the new connection to the server.</p>
4631 <li>When writing data to the client, the length of time to wait
4632 for an acknowledgement of a packet if the send buffer is
4635 <li>In <code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code> and <code class="module"><a href="../mod/mod_cgid.html">mod_cgid</a></code>,
4636 the length of time to wait for output from a CGI script.</li>
4638 <li>In <code class="module"><a href="../mod/mod_ext_filter.html">mod_ext_filter</a></code>, the length of time to
4639 wait for output from a filtering process.</li>
4641 <li>In <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>, the default timeout value if
4642 <code class="directive"><a href="../mod/mod_proxy.html#proxytimeout">ProxyTimeout</a></code> is not
4648 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4649 <div class="directive-section"><h2><a name="TraceEnable" id="TraceEnable">TraceEnable</a> <a name="traceenable" id="traceenable">Directive</a></h2>
4650 <table class="directive">
4651 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Determines the behavior on <code>TRACE</code> requests</td></tr>
4652 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>TraceEnable <var>[on|off|extended]</var></code></td></tr>
4653 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>TraceEnable on</code></td></tr>
4654 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4655 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4656 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4658 <p>This directive overrides the behavior of <code>TRACE</code> for both
4659 the core server and <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>. The default
4660 <code>TraceEnable on</code> permits <code>TRACE</code> requests per
4661 RFC 2616, which disallows any request body to accompany the request.
4662 <code>TraceEnable off</code> causes the core server and
4663 <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> to return a <code>405</code> (Method not
4664 allowed) error to the client.</p>
4666 <p>Finally, for testing and diagnostic purposes only, request
4667 bodies may be allowed using the non-compliant <code>TraceEnable
4668 extended</code> directive. The core (as an origin server) will
4669 restrict the request body to 64Kb (plus 8Kb for chunk headers if
4670 <code>Transfer-Encoding: chunked</code> is used). The core will
4671 reflect the full headers and all chunk headers with the response
4672 body. As a proxy server, the request body is not restricted to 64Kb.</p>
4674 <div class="note"><h3>Note</h3>
4676 <p>Despite claims to the contrary, enabling the <code>TRACE</code>
4677 method does not expose any security vulnerability in Apache httpd.
4678 The <code>TRACE</code> method is defined by the HTTP/1.1
4679 specification and implementations are expected to support it.</p>
4684 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4685 <div class="directive-section"><h2><a name="UnDefine" id="UnDefine">UnDefine</a> <a name="undefine" id="undefine">Directive</a></h2>
4686 <table class="directive">
4687 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Undefine the existence of a variable</td></tr>
4688 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UnDefine <var>parameter-name</var></code></td></tr>
4689 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
4690 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4691 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4693 <p>Undoes the effect of a <code class="directive"><a href="#define">Define</a></code> or
4694 of passing a <code>-D</code> argument to <code class="program"><a href="../programs/httpd.html">httpd</a></code>.</p>
4695 <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
4696 <code>-D</code> arguments in any startup scripts.</p>
4697 <p>While this directive is supported in virtual host context,
4698 the changes it makes are visible to any later configuration
4699 directives, beyond any enclosing virtual host.</p>
4702 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4703 <div class="directive-section"><h2><a name="UseCanonicalName" id="UseCanonicalName">UseCanonicalName</a> <a name="usecanonicalname" id="usecanonicalname">Directive</a></h2>
4704 <table class="directive">
4705 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures how the server determines its own name and
4707 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UseCanonicalName On|Off|DNS</code></td></tr>
4708 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>UseCanonicalName Off</code></td></tr>
4709 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
4710 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4711 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4713 <p>In many situations Apache httpd must construct a <em>self-referential</em>
4714 URL -- that is, a URL that refers back to the same server. With
4715 <code>UseCanonicalName On</code> Apache httpd will use the hostname and port
4716 specified in the <code class="directive"><a href="#servername">ServerName</a></code>
4717 directive to construct the canonical name for the server. This name
4718 is used in all self-referential URLs, and for the values of
4719 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> in CGIs.</p>
4721 <p>With <code>UseCanonicalName Off</code> Apache httpd will form
4722 self-referential URLs using the hostname and port supplied by
4723 the client if any are supplied (otherwise it will use the
4724 canonical name, as defined above). These values are the same
4725 that are used to implement <a href="../vhosts/name-based.html">name-based virtual hosts</a>
4726 and are available with the same clients. The CGI variables
4727 <code>SERVER_NAME</code> and <code>SERVER_PORT</code> will be
4728 constructed from the client supplied values as well.</p>
4730 <p>An example where this may be useful is on an intranet server
4731 where you have users connecting to the machine using short
4732 names such as <code>www</code>. You'll notice that if the users
4733 type a shortname and a URL which is a directory, such as
4734 <code>http://www/splat</code>, <em>without the trailing
4735 slash</em>, then Apache httpd will redirect them to
4736 <code>http://www.example.com/splat/</code>. If you have
4737 authentication enabled, this will cause the user to have to
4738 authenticate twice (once for <code>www</code> and once again
4739 for <code>www.example.com</code> -- see <a href="http://wiki.apache.org/httpd/FAQ#Why_does_Apache_ask_for_my_password_twice_before_serving_a_file.3F">
4740 the FAQ on this subject for more information</a>). But if
4741 <code class="directive">UseCanonicalName</code> is set <code>Off</code>, then
4742 Apache httpd will redirect to <code>http://www/splat/</code>.</p>
4744 <p>There is a third option, <code>UseCanonicalName DNS</code>,
4745 which is intended for use with mass IP-based virtual hosting to
4746 support ancient clients that do not provide a
4747 <code>Host:</code> header. With this option, Apache httpd does a
4748 reverse DNS lookup on the server IP address that the client
4749 connected to in order to work out self-referential URLs.</p>
4751 <div class="warning"><h3>Warning</h3>
4752 <p>If CGIs make assumptions about the values of <code>SERVER_NAME</code>,
4753 they may be broken by this option. The client is essentially free
4754 to give whatever value they want as a hostname. But if the CGI is
4755 only using <code>SERVER_NAME</code> to construct self-referential URLs,
4756 then it should be just fine.</p>
4761 <li><code class="directive"><a href="#usecanonicalphysicalport">UseCanonicalPhysicalPort</a></code></li>
4762 <li><code class="directive"><a href="#servername">ServerName</a></code></li>
4763 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
4766 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4767 <div class="directive-section"><h2><a name="UseCanonicalPhysicalPort" id="UseCanonicalPhysicalPort">UseCanonicalPhysicalPort</a> <a name="usecanonicalphysicalport" id="usecanonicalphysicalport">Directive</a></h2>
4768 <table class="directive">
4769 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Configures how the server determines its own port</td></tr>
4770 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>UseCanonicalPhysicalPort On|Off</code></td></tr>
4771 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>UseCanonicalPhysicalPort Off</code></td></tr>
4772 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory</td></tr>
4773 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4774 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4776 <p>In many situations Apache httpd must construct a <em>self-referential</em>
4777 URL -- that is, a URL that refers back to the same server. With
4778 <code>UseCanonicalPhysicalPort On</code>, Apache httpd will, when
4779 constructing the canonical port for the server to honor
4780 the <code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code> directive,
4781 provide the actual physical port number being used by this request
4782 as a potential port. With <code>UseCanonicalPhysicalPort Off</code>,
4783 Apache httpd will not ever use the actual physical port number, instead
4784 relying on all configured information to construct a valid port number.</p>
4786 <div class="note"><h3>Note</h3>
4787 <p>The ordering of the lookup when the physical port is used is as
4790 <dt><code>UseCanonicalName On</code></dt>
4793 <li>Port provided in <code class="directive"><a href="#servername">Servername</a></code></li>
4794 <li>Physical port</li>
4795 <li>Default port</li>
4798 <dt><code>UseCanonicalName Off | DNS</code></dt>
4801 <li>Parsed port from <code>Host:</code> header</li>
4802 <li>Physical port</li>
4803 <li>Port provided in <code class="directive"><a href="#servername">Servername</a></code></li>
4804 <li>Default port</li>
4809 <p>With <code>UseCanonicalPhysicalPort Off</code>, the
4810 physical ports are removed from the ordering.</p>
4816 <li><code class="directive"><a href="#usecanonicalname">UseCanonicalName</a></code></li>
4817 <li><code class="directive"><a href="#servername">ServerName</a></code></li>
4818 <li><code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code></li>
4821 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4822 <div class="directive-section"><h2><a name="VirtualHost" id="VirtualHost"><VirtualHost></a> <a name="virtualhost" id="virtualhost">Directive</a></h2>
4823 <table class="directive">
4824 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Contains directives that apply only to a specific
4825 hostname or IP address</td></tr>
4826 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code><VirtualHost
4827 <var>addr</var>[:<var>port</var>] [<var>addr</var>[:<var>port</var>]]
4828 ...> ... </VirtualHost></code></td></tr>
4829 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
4830 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4831 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4833 <p><code class="directive"><VirtualHost></code> and
4834 <code></VirtualHost></code> are used to enclose a group of
4835 directives that will apply only to a particular virtual host. Any
4836 directive that is allowed in a virtual host context may be
4837 used. When the server receives a request for a document on a
4838 particular virtual host, it uses the configuration directives
4839 enclosed in the <code class="directive"><VirtualHost></code>
4840 section. <var>Addr</var> can be any of the following, optionally followed by
4841 a colon and a port number (or *):</p>
4844 <li>The IP address of the virtual host;</li>
4846 <li>A fully qualified domain name for the IP address of the
4847 virtual host (not recommended);</li>
4849 <li>The character <code>*</code>, which acts as a wildcard and matches
4850 any IP address.</li>
4852 <li>The string <code>_default_</code>, which is an alias for <code>*</code></li>
4856 <pre class="prettyprint lang-config"><VirtualHost 10.1.2.3:80>
4857 ServerAdmin webmaster@host.example.com
4858 DocumentRoot "/www/docs/host.example.com"
4859 ServerName host.example.com
4860 ErrorLog "logs/host.example.com-error_log"
4861 TransferLog "logs/host.example.com-access_log"
4862 </VirtualHost></pre>
4866 <p>IPv6 addresses must be specified in square brackets because
4867 the optional port number could not be determined otherwise. An
4868 IPv6 example is shown below:</p>
4870 <pre class="prettyprint lang-config"><VirtualHost [2001:db8::a00:20ff:fea7:ccea]:80>
4871 ServerAdmin webmaster@host.example.com
4872 DocumentRoot "/www/docs/host.example.com"
4873 ServerName host.example.com
4874 ErrorLog "logs/host.example.com-error_log"
4875 TransferLog "logs/host.example.com-access_log"
4876 </VirtualHost></pre>
4879 <p>Each Virtual Host must correspond to a different IP address,
4880 different port number, or a different host name for the server,
4881 in the former case the server machine must be configured to
4882 accept IP packets for multiple addresses. (If the machine does
4883 not have multiple network interfaces, then this can be
4884 accomplished with the <code>ifconfig alias</code> command -- if
4885 your OS supports it).</p>
4887 <div class="note"><h3>Note</h3>
4888 <p>The use of <code class="directive"><VirtualHost></code> does
4889 <strong>not</strong> affect what addresses Apache httpd listens on. You
4890 may need to ensure that Apache httpd is listening on the correct addresses
4891 using <code class="directive"><a href="../mod/mpm_common.html#listen">Listen</a></code>.</p>
4894 <p>A <code class="directive"><a href="#servername">ServerName</a></code> should be
4895 specified inside each <code class="directive"><VirtualHost></code> block. If it is absent, the
4896 <code class="directive"><a href="#servername">ServerName</a></code> from the "main"
4897 server configuration will be inherited.</p>
4899 <p>When a request is received, the server first maps it to the best matching
4900 <code class="directive"><VirtualHost></code> based on the local
4901 IP address and port combination only. Non-wildcards have a higher
4902 precedence. If no match based on IP and port occurs at all, the
4903 "main" server configuration is used.</p>
4905 <p>If multiple virtual hosts contain the best matching IP address and port,
4906 the server selects from these virtual hosts the best match based on the
4907 requested hostname. If no matching name-based virtual host is found,
4908 then the first listed virtual host that matched the IP address will be
4909 used. As a consequence, the first listed virtual host for a given IP address
4910 and port combination is the default virtual host for that IP and port
4913 <div class="warning"><h3>Security</h3>
4914 <p>See the <a href="../misc/security_tips.html">security tips</a>
4915 document for details on why your security could be compromised if the
4916 directory where log files are stored is writable by anyone other
4917 than the user that starts the server.</p>
4922 <li><a href="../vhosts/">Apache HTTP Server Virtual Host documentation</a></li>
4923 <li><a href="../dns-caveats.html">Issues Regarding DNS and
4924 Apache HTTP Server</a></li>
4925 <li><a href="../bind.html">Setting
4926 which addresses and ports Apache HTTP Server uses</a></li>
4927 <li><a href="../sections.html">How <Directory>, <Location>
4928 and <Files> sections work</a> for an explanation of how these
4929 different sections are combined when a request is received</li>
4932 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
4933 <div class="directive-section"><h2><a name="Warning" id="Warning">Warning</a> <a name="warning" id="warning">Directive</a></h2>
4934 <table class="directive">
4935 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Warn from configuration parsing with a custom message</td></tr>
4936 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>Warning <var>message</var></code></td></tr>
4937 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
4938 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Core</td></tr>
4939 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>core</td></tr>
4940 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>2.5 and later</td></tr>
4942 <p>If an issue can be detected from within the configuration, this
4943 directive can be used to generate a custom warning message. The
4944 configuration parsing is not halted. The typical use is to check
4945 whether some user define options are set, and warn if not.</p>
4947 <pre class="prettyprint lang-config"># Example
4948 # tell when ReverseProxy is not set
4949 <IfDefine !ReverseProxy>
4950 Warning "reverse proxy is not started, hope this is okay!"
4953 <IfDefine ReverseProxy>
4954 # define custom proxy configuration
4955 </IfDefine></pre>
4961 <div class="bottomlang">
4962 <p><span>Available Languages: </span><a href="../de/mod/core.html" hreflang="de" rel="alternate" title="Deutsch"> de </a> |
4963 <a href="../en/mod/core.html" title="English"> en </a> |
4964 <a href="../es/mod/core.html" hreflang="es" rel="alternate" title="Español"> es </a> |
4965 <a href="../fr/mod/core.html" hreflang="fr" rel="alternate" title="Français"> fr </a> |
4966 <a href="../ja/mod/core.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
4967 <a href="../tr/mod/core.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
4968 </div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed again by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Freenode, or sent to our <a href="http://httpd.apache.org/lists.html">mailing lists</a>.</div>
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