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8 <title>Mapping URLs to Filesystem Locations - Apache HTTP Server</title>
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14 <p class="menu"><a href="./mod/">Modules</a> | <a href="./mod/directives.html">Directives</a> | <a href="./faq/">FAQ</a> | <a href="./glossary.html">Glossary</a> | <a href="./sitemap.html">Sitemap</a></p>
15 <p class="apache">Apache HTTP Server Version 2.1</p>
16 <img alt="" src="./images/feather.gif" /></div>
17 <div class="up"><a href="./"><img title="<-" alt="<-" src="./images/left.gif" /></a></div>
19 <a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs-project/">Documentation</a> > <a href="./">Version 2.1</a></div><div id="page-content"><div id="preamble"><h1>Mapping URLs to Filesystem Locations</h1>
21 <p><span>Available Languages: </span><a href="./en/urlmapping.html" title="English"> en </a> |
22 <a href="./ja/urlmapping.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
23 <a href="./ko/urlmapping.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p>
26 <p>This document explains how Apache uses the URL of a request
27 to determine the filesystem location from which to serve a
30 <div id="quickview"><ul id="toc"><li><img alt="" src="./images/down.gif" /> <a href="#related">Related Modules and Directives</a></li>
31 <li><img alt="" src="./images/down.gif" /> <a href="#documentroot">DocumentRoot</a></li>
32 <li><img alt="" src="./images/down.gif" /> <a href="#outside">Files Outside the DocumentRoot</a></li>
33 <li><img alt="" src="./images/down.gif" /> <a href="#user">User Directories</a></li>
34 <li><img alt="" src="./images/down.gif" /> <a href="#redirect">URL Redirection</a></li>
35 <li><img alt="" src="./images/down.gif" /> <a href="#proxy">Reverse Proxy</a></li>
36 <li><img alt="" src="./images/down.gif" /> <a href="#rewrite">Rewriting Engine</a></li>
37 <li><img alt="" src="./images/down.gif" /> <a href="#notfound">File Not Found</a></li>
39 <div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
41 <h2><a name="related" id="related">Related Modules and Directives</a></h2>
43 <table class="related"><tr><th>Related Modules</th><th>Related Directives</th></tr><tr><td><ul><li><code class="module"><a href="./mod/mod_alias.html">mod_alias</a></code></li><li><code class="module"><a href="./mod/mod_proxy.html">mod_proxy</a></code></li><li><code class="module"><a href="./mod/mod_rewrite.html">mod_rewrite</a></code></li><li><code class="module"><a href="./mod/mod_userdir.html">mod_userdir</a></code></li><li><code class="module"><a href="./mod/mod_speling.html">mod_speling</a></code></li><li><code class="module"><a href="./mod/mod_vhost_alias.html">mod_vhost_alias</a></code></li></ul></td><td><ul><li><code class="directive"><a href="./mod/mod_alias.html#alias">Alias</a></code></li><li><code class="directive"><a href="./mod/mod_alias.html#aliasmatch">AliasMatch</a></code></li><li><code class="directive"><a href="./mod/mod_speling.html#checkspelling">CheckSpelling</a></code></li><li><code class="directive"><a href="./mod/core.html#documentroot">DocumentRoot</a></code></li><li><code class="directive"><a href="./mod/core.html#errordocument">ErrorDocument</a></code></li><li><code class="directive"><a href="./mod/core.html#options">Options</a></code></li><li><code class="directive"><a href="./mod/mod_proxy.html#proxypass">ProxyPass</a></code></li><li><code class="directive"><a href="./mod/mod_proxy.html#proxypassreverse">ProxyPassReverse</a></code></li><li><code class="directive"><a href="./mod/mod_proxy.html#proxypassreversecookiedomain">ProxyPassReverseCookieDomain</a></code></li><li><code class="directive"><a href="./mod/mod_proxy.html#proxypassreversecookiepath">ProxyPassReverseCookiePath</a></code></li><li><code class="directive"><a href="./mod/mod_alias.html#redirect">Redirect</a></code></li><li><code class="directive"><a href="./mod/mod_alias.html#redirectmatch">RedirectMatch</a></code></li><li><code class="directive"><a href="./mod/mod_rewrite.html#rewritecond">RewriteCond</a></code></li><li><code class="directive"><a href="./mod/mod_rewrite.html#rewritematch">RewriteMatch</a></code></li><li><code class="directive"><a href="./mod/mod_alias.html#scriptalias">ScriptAlias</a></code></li><li><code class="directive"><a href="./mod/mod_alias.html#scriptaliasmatch">ScriptAliasMatch</a></code></li><li><code class="directive"><a href="./mod/mod_userdir.html#userdir">UserDir</a></code></li></ul></td></tr></table>
44 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
46 <h2><a name="documentroot" id="documentroot">DocumentRoot</a></h2>
48 <p>In deciding what file to serve for a given request, Apache's
49 default behavior is to take the URL-Path for the request (the part
50 of the URL following the hostname and port) and add it to the end
51 of the <code class="directive"><a href="./mod/core.html#documentroot">DocumentRoot</a></code> specified
52 in your configuration files. Therefore, the files and directories
53 underneath the <code class="directive"><a href="./mod/core.html#documentroot">DocumentRoot</a></code>
54 make up the basic document tree which will be visible from the
57 <p>Apache is also capable of <a href="vhosts/">Virtual
58 Hosting</a>, where the server receives requests for more than one
59 host. In this case, a different <code class="directive"><a href="./mod/core.html#documentroot">DocumentRoot</a></code> can be specified for each
60 virtual host, or alternatively, the directives provided by the
61 module <code class="module"><a href="./mod/mod_vhost_alias.html">mod_vhost_alias</a></code> can
62 be used to dynamically determine the appropriate place from which
63 to serve content based on the requested IP address or
65 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
67 <h2><a name="outside" id="outside">Files Outside the DocumentRoot</a></h2>
69 <p>There are frequently circumstances where it is necessary to
70 allow web access to parts of the filesystem that are not strictly
71 underneath the <code class="directive"><a href="./mod/core.html#documentroot">DocumentRoot</a></code>. Apache offers several
72 different ways to accomplish this. On Unix systems, symbolic links
73 can bring other parts of the filesystem under the <code class="directive"><a href="./mod/core.html#documentroot">DocumentRoot</a></code>. For security reasons,
74 Apache will follow symbolic links only if the <code class="directive"><a href="./mod/core.html#options">Options</a></code> setting for the relevant
75 directory includes <code>FollowSymLinks</code> or
76 <code>SymLinksIfOwnerMatch</code>.</p>
78 <p>Alternatively, the <code class="directive"><a href="./mod/mod_alias.html#alias">Alias</a></code> directive will map any part
79 of the filesystem into the web space. For example, with</p>
81 <div class="example"><p><code>Alias /docs /var/web</code></p></div>
83 <p>the URL <code>http://www.example.com/docs/dir/file.html</code>
84 will be served from <code>/var/web/dir/file.html</code>. The
85 <code class="directive"><a href="./mod/mod_alias.html#scriptalias">ScriptAlias</a></code> directive
86 works the same way, with the additional effect that all content
87 located at the target path is treated as CGI scripts.</p>
89 <p>For situations where you require additional flexibility, you
90 can use the <code class="directive"><a href="./mod/mod_alias.html#aliasmatch">AliasMatch</a></code> and
91 <code class="directive"><a href="./mod/mod_alias.html#scriptaliasmatch">ScriptAliasMatch</a></code>
92 directives to do powerful regular-expression based matching and
93 substitution. For example,</p>
95 <div class="example"><p><code>ScriptAliasMatch ^/~([a-zA-Z0-9]+)/cgi-bin/(.+)
96 /home/$1/cgi-bin/$2</code></p></div>
98 <p>will map a request to
99 <code>http://example.com/~user/cgi-bin/script.cgi</code> to the
100 path <code>/home/user/cgi-bin/script.cgi</code> and will treat
101 the resulting file as a CGI script.</p>
102 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
103 <div class="section">
104 <h2><a name="user" id="user">User Directories</a></h2>
106 <p>Traditionally on Unix systems, the home directory of a
107 particular <em>user</em> can be referred to as
108 <code>~user/</code>. The module <code class="module"><a href="./mod/mod_userdir.html">mod_userdir</a></code>
109 extends this idea to the web by allowing files under each user's
110 home directory to be accessed using URLs such as the
113 <div class="example"><p><code>http://www.example.com/~user/file.html</code></p></div>
115 <p>For security reasons, it is inappropriate to give direct
116 access to a user's home directory from the web. Therefore, the
117 <code class="directive"><a href="./mod/mod_userdir.html#userdir">UserDir</a></code> directive
118 specifies a directory underneath the user's home directory
119 where web files are located. Using the default setting of
120 <code>Userdir public_html</code>, the above URL maps to a file
122 <code>/home/user/public_html/file.html</code> where
123 <code>/home/user/</code> is the user's home directory as
124 specified in <code>/etc/passwd</code>.</p>
126 <p>There are also several other forms of the
127 <code>Userdir</code> directive which you can use on systems
128 where <code>/etc/passwd</code> does not contain the location of
129 the home directory.</p>
131 <p>Some people find the "~" symbol (which is often encoded on the
132 web as <code>%7e</code>) to be awkward and prefer to use an
133 alternate string to represent user directories. This functionality
134 is not supported by mod_userdir. However, if users' home
135 directories are structured in a regular way, then it is possible
136 to use the <code class="directive"><a href="./mod/mod_alias.html#aliasmatch">AliasMatch</a></code>
137 directive to achieve the desired effect. For example, to make
138 <code>http://www.example.com/upages/user/file.html</code> map to
139 <code>/home/user/public_html/file.html</code>, use the following
140 <code>AliasMatch</code> directive:</p>
142 <div class="example"><p><code>AliasMatch ^/upages/([a-zA-Z0-9]+)/?(.*)
143 /home/$1/public_html/$2</code></p></div>
144 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
145 <div class="section">
146 <h2><a name="redirect" id="redirect">URL Redirection</a></h2>
148 <p>The configuration directives discussed in the above sections
149 tell Apache to get content from a specific place in the filesystem
150 and return it to the client. Sometimes, it is desirable instead to
151 inform the client that the requested content is located at a
152 different URL, and instruct the client to make a new request with
153 the new URL. This is called <em>redirection</em> and is
154 implemented by the <code class="directive"><a href="./mod/mod_alias.html#redirect">Redirect</a></code> directive. For example, if
155 the contents of the directory <code>/foo/</code> under the
156 <code class="directive"><a href="./mod/core.html#documentroot">DocumentRoot</a></code> are moved
157 to the new directory <code>/bar/</code>, you can instruct clients
158 to request the content at the new location as follows:</p>
160 <div class="example"><p><code>Redirect permanent /foo/
161 http://www.example.com/bar/</code></p></div>
163 <p>This will redirect any URL-Path starting in
164 <code>/foo/</code> to the same URL path on the
165 <code>www.example.com</code> server with <code>/bar/</code>
166 substituted for <code>/foo/</code>. You can redirect clients to
167 any server, not only the origin server.</p>
169 <p>Apache also provides a <code class="directive"><a href="./mod/mod_alias.html#redirectmatch">RedirectMatch</a></code> directive for more
170 complicated rewriting problems. For example, to redirect requests
171 for the site home page to a different site, but leave all other
172 requests alone, use the following configuration:</p>
174 <div class="example"><p><code>RedirectMatch permanent ^/$
175 http://www.example.com/startpage.html</code></p></div>
177 <p>Alternatively, to temporarily redirect all pages on one site
178 to a particular page on another site, use the following:</p>
180 <div class="example"><p><code>RedirectMatch temp .*
181 http://othersite.example.com/startpage.html</code></p></div>
182 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
183 <div class="section">
184 <h2><a name="proxy" id="proxy">Reverse Proxy</a></h2>
186 <p>Apache also allows you to bring remote documents into the URL space
187 of the local server. This technique is called <em>reverse
188 proxying</em> because the web server acts like a proxy server by
189 fetching the documents from a remote server and returning them to the
190 client. It is different from normal proxying because, to the client,
191 it appears the documents originate at the reverse proxy server.</p>
193 <p>In the following example, when clients request documents under the
194 <code>/foo/</code> directory, the server fetches those documents from
195 the <code>/bar/</code> directory on <code>internal.example.com</code>
196 and returns them to the client as if they were from the local
199 <div class="example"><p><code>
200 ProxyPass /foo/ http://internal.example.com/bar/<br />
201 ProxyPassReverse /foo/ http://internal.example.com/bar/
202 ProxyPassReverseCookieDomain internal.example.com public.example.com
203 ProxyPassReverseCookiePath /foo/ /bar/
206 <p>The <code class="directive"><a href="./mod/mod_proxy.html#proxypass">ProxyPass</a></code> configures
207 the server to fetch the appropriate documents, while the
208 <code class="directive"><a href="./mod/mod_proxy.html#proxypassreverse">ProxyPassReverse</a></code>
209 directive rewrites redirects originating at
210 <code>internal.example.com</code> so that they target the appropriate
211 directory on the local server. Similarly, the
212 <code class="directive"><a href="./mod/mod_proxy.html#proxypassreversecookiedomain">ProxyPassReverseCookieDomain</a></code>
213 and <code class="directive"><a href="./mod/mod_proxy.html#proxypassreversecookiedomain">ProxyPassReverseCookieDomain</a></code>
214 rewrite cookies set by the backend server.</p>
215 <p>It is important to note, however, that
216 links inside the documents will not be rewritten. So any absolute
217 links on <code>internal.example.com</code> will result in the client
218 breaking out of the proxy server and requesting directly from
219 <code>internal.example.com</code>. A third-party module
220 <a href="http://apache.webthing.com/mod_proxy_html/">mod_proxy_html</a>
221 is available to rewrite links in HTML and XHTML.</p>
222 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
223 <div class="section">
224 <h2><a name="rewrite" id="rewrite">Rewriting Engine</a></h2>
226 <p>When even more powerful substitution is required, the rewriting
227 engine provided by <code class="module"><a href="./mod/mod_rewrite.html">mod_rewrite</a></code>
228 can be useful. The directives provided by this module use
229 characteristics of the request such as browser type or source IP
230 address in deciding from where to serve content. In addition,
231 mod_rewrite can use external database files or programs to
232 determine how to handle a request. The rewriting engine is capable
233 of performing all three types of mappings discussed above:
234 internal redirects (aliases), external redirects, and proxying.
235 Many practical examples employing mod_rewrite are discussed in the
236 <a href="misc/rewriteguide.html">URL Rewriting Guide</a>.</p>
237 </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
238 <div class="section">
239 <h2><a name="notfound" id="notfound">File Not Found</a></h2>
241 <p>Inevitably, URLs will be requested for which no matching
242 file can be found in the filesystem. This can happen for
243 several reasons. In some cases, it can be a result of moving
244 documents from one location to another. In this case, it is
245 best to use <a href="#redirect">URL redirection</a> to inform
246 clients of the new location of the resource. In this way, you
247 can assure that old bookmarks and links will continue to work,
248 even though the resource is at a new location.</p>
250 <p>Another common cause of "File Not Found" errors is
251 accidental mistyping of URLs, either directly in the browser,
252 or in HTML links. Apache provides the module
253 <code class="module"><a href="./mod/mod_speling.html">mod_speling</a></code> (sic) to help with
254 this problem. When this module is activated, it will intercept
255 "File Not Found" errors and look for a resource with a similar
256 filename. If one such file is found, mod_speling will send an
257 HTTP redirect to the client informing it of the correct
258 location. If several "close" files are found, a list of
259 available alternatives will be presented to the client.</p>
261 <p>An especially useful feature of mod_speling, is that it will
262 compare filenames without respect to case. This can help
263 systems where users are unaware of the case-sensitive nature of
264 URLs and the unix filesystem. But using mod_speling for
265 anything more than the occasional URL correction can place
266 additional load on the server, since each "incorrect" request
267 is followed by a URL redirection and a new request from the
270 <p>If all attempts to locate the content fail, Apache returns
271 an error page with HTTP status code 404 (file not found). The
272 appearance of this page is controlled with the
273 <code class="directive"><a href="./mod/core.html#errordocument">ErrorDocument</a></code> directive
274 and can be customized in a flexible manner as discussed in the
275 <a href="custom-error.html">Custom error responses</a>
278 <div class="bottomlang">
279 <p><span>Available Languages: </span><a href="./en/urlmapping.html" title="English"> en </a> |
280 <a href="./ja/urlmapping.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> |
281 <a href="./ko/urlmapping.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p>
282 </div><div id="footer">
283 <p class="apache">Copyright 1999-2004 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
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