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-<title>When not to use mod_rewrite - Apache HTTP Server</title>
+<title>When not to use mod_rewrite - Apache HTTP Server Version 2.5</title>
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<body id="manual-page"><div id="page-header">
-<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>
-<p class="apache">Apache HTTP Server Version 2.3</p>
-<img alt="" src="../images/feather.gif" /></div>
+<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>
+<p class="apache">Apache HTTP Server Version 2.5</p>
+<img alt="" src="../images/feather.png" /></div>
<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div>
<div id="path">
-<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.
3</a> > <a href="./">Rewrite</a></div><div id="page-content"><div id="preamble"><h1>When not to use mod_rewrite</h1>
+<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="./">Rewrite</a></div><div id="page-content"><div id="preamble"><h1>When not to use mod_rewrite</h1>
<div class="toplang">
-<p><span>Available Languages: </span><a href="../en/rewrite/avoid.html" title="English"> en </a></p>
+<p><span>Available Languages: </span><a href="../en/rewrite/avoid.html" title="English"> en </a> |
+<a href="../fr/rewrite/avoid.html" hreflang="fr" rel="alternate" title="Français"> fr </a></p>
</div>
-<p>This document supplements the <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>
+<p>This document supplements the <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>
<a href="../mod/mod_rewrite.html">reference documentation</a>. It describes
-perhaps one of the most important concepts about mod_rewrite - namely,
+perhaps one of the most important concepts about <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> - namely,
when to avoid using it.</p>
-<p>mod_rewrite should be considered a last resort, when other
+<p><code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> should be considered a last resort, when other
alternatives are found wanting. Using it when there are simpler
alternatives leads to configurations which are confusing, fragile, and
hard to maintain. Understanding what other alternatives are available is
-a very important step towards mod_rewrite mastery.</p>
+a very important step towards <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> mastery.</p>
<p>Note that many of these examples won't work unchanged in your
particular server configuration, so it's important that you understand
them, rather than merely cutting and pasting the examples into your
configuration.</p>
-<div class="warning">This document is a work in progress.</div>
+<p>The most common situation in which <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> is
+the right tool is when the very best solution requires access to the
+server configuration files, and you don't have that access. Some
+configuration directives are only available in the server configuration
+file. So if you are in a hosting situation where you only have .htaccess
+files to work with, you may need to resort to
+<code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>.</p>
</div>
<div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#redirect">Simple Redirection</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#vhosts">Virtual Hosting</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#proxy">Simple Proxying</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#setenv">Environment Variable Testing</a></li>
-</ul><h3>See also</h3><ul class="seealso"><li><a href="../mod/mod_rewrite.html">Module documentation</a></li><li><a href="intro.html">mod_rewrite introduction</a></li><li><a href="remapping.html">Redirection and remapping</a></li><li><a href="access.html">Controlling access</a></li><li><a href="vhosts.html">Virtual hosts</a></li><li><a href="proxy.html">Proxying</a></li><li><a href="advanced.html">Advanced techniques and tricks</a></li></ul></div>
+</ul><h3>See also</h3><ul class="seealso"><li><a href="../mod/mod_rewrite.html">Module documentation</a></li><li><a href="intro.html">mod_rewrite introduction</a></li><li><a href="remapping.html">Redirection and remapping</a></li><li><a href="access.html">Controlling access</a></li><li><a href="vhosts.html">Virtual hosts</a></li><li><a href="proxy.html">Proxying</a></li><li><a href="rewritemap.html">Using RewriteMap</a></li><li><a href="advanced.html">Advanced techniques</a></li><li><a href="#comments_section">Comments</a></li></ul></div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
-<h2><a name="redirect" id="redirect">Simple Redirection</a></h2>
+<h2><a name="redirect" id="redirect">Simple Redirection</a><a title="Permanent link" href="#redirect" class="permalink">¶</a></h2>
<p><code class="module"><a href="../mod/mod_alias.html">mod_alias</a></code> provides the <code class="directive"><a href="../mod/mod_alias.html#redirect">Redirect</a></code> and <code class="directive"><a href="../mod/mod_alias.html#redirectmatch">RedirectMatch</a></code> directives, which provide a
<p>To redirect URLs under <code>/one</code> to
<code>http://one.example.com</code>, do the following:</p>
-<div class="example"><p><code>
-Redirect /one/ http://one.example.com/
-</code></p></div>
+<pre class="prettyprint lang-config">Redirect "/one/" "http://one.example.com/"</pre>
+
+
+<p>To redirect one hostname to another, for example
+<code>example.com</code> to <code>www.example.com</code>, see the
+<a href="remapping.html#canonicalhost">Canonical Hostnames</a>
+recipe.</p>
<p>To redirect <code>http</code> URLs to <code>https</code>, do the
following:</p>
-<div class="example"><p><code>
-<VirtualHost *:80>
-ServerName www.example.com<br />
-Redirect / https://www.example.com/<br />
-</VirtualHost >
-<br />
+<pre class="prettyprint lang-config"><VirtualHost *:80>
+ ServerName www.example.com
+ Redirect "/" "https://www.example.com/"
+</VirtualHost>
+
<VirtualHost *:443>
-ServerName www.example.com<br />
-<br />
-# ... SSL configuration goes here<br />
-</VirtualHost >
-</code></p></div>
+ ServerName www.example.com
+ # ... SSL configuration goes here
+</VirtualHost></pre>
+
<p>The use of <code>RewriteRule</code> to perform this task may be
appropriate if there are other <code>RewriteRule</code> directives in
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
-<h2><a name="alias" id="alias">URL Aliasing</a></h2>
+<h2><a name="alias" id="alias">URL Aliasing</a><a title="Permanent link" href="#alias" class="permalink">¶</a></h2>
<p>The <code class="directive"><a href="../mod/mod_alias.html#alias">Alias</a></code> directive
provides mapping from a URI to a directory - usually a directory outside
of your <code class="directive"><a href="../mod/core.html#documentroot">DocumentRoot</a></code>. Although it
-is possible to perform this mappint with <code>mod_rewrite</code>,
-<code>Alias</code> is the preferred method, for reasons of simplicity
-and performance.</p>
+is possible to perform this mapping with <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>,
+<code class="directive"><a href="../mod/mod_alias.html#alias">Alias</a></code> is the preferred method, for
+reasons of simplicity and performance.</p>
-<div class="example"><h3>Using Alias</h3><p><code>
-Alias /cats /var/www/virtualhosts/felines/htdocs
-</code></p></div>
+<div class="example"><h3>Using Alias</h3><pre class="prettyprint lang-config">Alias "/cats" "/var/www/virtualhosts/felines/htdocs"</pre>
+</div>
<p>
-The use of <code>mod_rewrite</code> to perform this mapping may be
+The use of <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> to perform this mapping may be
appropriate when you do not have access to the server configuration
files. Alias may only be used in server or virtualhost context, and not
in a <code>.htaccess</code> file.
server.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
-<h2><a name="vhosts" id="vhosts">Virtual Hosting</a></h2>
+<h2><a name="vhosts" id="vhosts">Virtual Hosting</a><a title="Permanent link" href="#vhosts" class="permalink">¶</a></h2>
<p>Although it is possible to handle <a href="vhosts.html">virtual hosts
-with mod_rewrite</a>, it is </p>
+with mod_rewrite</a>, it is seldom the right way. Creating individual
+<code class="directive"><a href="../mod/core.html#virtualhost"><VirtualHost></a></code> blocks is
+almost always the right way to go. In the
+event that you have an enormous number of virtual hosts, consider using
+<code class="module"><a href="../mod/mod_vhost_alias.html">mod_vhost_alias</a></code> to create these hosts automatically.</p>
+
+<p>Modules such as <code class="module"><a href="../mod/mod_macro.html">mod_macro</a></code> are
+also useful for creating a large number of virtual hosts dynamically.</p>
+
+<p>Using <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> for vitualhost creation may be
+appropriate if you are using a hosting service that does not provide
+you access to the server configuration files, and you are therefore
+restricted to configuration using <code>.htaccess</code> files.</p>
+
+<p>See the <a href="vhosts.html">virtual hosts with mod_rewrite</a>
+document for more details on how you might accomplish this if it still
+seems like the right approach.</p>
+
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
-<h2><a name="proxy" id="proxy">Simple Proxying</a></h2>
-<p>ProxyPass</p>
+<h2><a name="proxy" id="proxy">Simple Proxying</a><a title="Permanent link" href="#proxy" class="permalink">¶</a></h2>
+
+<p><code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> provides the <a href="flags.html#flag_p">[P]</a> flag to pass rewritten URIs through
+<code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>.</p>
+
+<pre class="prettyprint lang-config">RewriteRule "^/?images(.*)" "http://imageserver.local/images$1" [P]</pre>
+
+
+<p>However, in many cases, when there is no actual pattern matching
+needed, as in the example shown above, the <code class="directive"><a href="../mod/mod_proxy.html#proxypass">ProxyPass</a></code> directive is a better choice.
+The example here could be rendered as:</p>
+
+<pre class="prettyprint lang-config">ProxyPass "/images/" "http://imageserver.local/images/"</pre>
+
+
+<p>Note that whether you use <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> or <code class="directive"><a href="../mod/mod_proxy.html#proxypass">ProxyPass</a></code>, you'll still need to use the
+<code class="directive"><a href="../mod/mod_proxy.html#proxypassreverse">ProxyPassReverse</a></code> directive to
+catch redirects issued from the back-end server:</p>
+
+<pre class="prettyprint lang-config">ProxyPassReverse "/images/" "http://imageserver.local/images/"</pre>
+
+
+<p>You may need to use <code>RewriteRule</code> instead when there are
+other <code>RewriteRule</code>s in effect in the same scope, as a
+<code>RewriteRule</code> will usually take effect before a
+<code>ProxyPass</code>, and so may preempt what you're trying to
+accomplish.</p>
+
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
-<h2><a name="setenv" id="setenv">Environment Variable Testing</a></h2>
+<h2><a name="setenv" id="setenv">Environment Variable Testing</a><a title="Permanent link" href="#setenv" class="permalink">¶</a></h2>
+
+<p><code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> is frequently used to take a particular
+action based on the presence or absence of a particular environment
+variable or request header. This can be done more efficiently using the
+<code class="directive"><a href="../mod/core.html#if"><If></a></code>.</p>
+
+<p>Consider, for example, the common scenario where
+<code class="directive">RewriteRule</code> is used to enforce a canonical
+hostname, such as <code>www.example.com</code> instead of
+<code>example.com</code>. This can be done using the <code class="directive"><a href="../mod/core.html#if"><If></a></code> directive, as shown here:</p>
+
+<pre class="prettyprint lang-config"><If "req('Host') != 'www.example.com'">
+ Redirect "/" "http://www.example.com/"
+</If></pre>
+
-<div class="note">Parts of this section are applicable only to Apache HTTP
-Server 2.3 and later.</div>
+<p>This technique can be used to take actions based on any request
+header, response header, or environment variable, replacing
+<code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> in many common scenarios.</p>
-<p>Using SetEnvIf and <If> (2.3 and later.)</p>
+<p>See especially the <a href="../expr.html">expression evaluation
+documentation</a> for a overview of what types of expressions you can
+use in <code class="directive"><a href="../mod/core.html#if"><If></a></code> sections,
+and in certain other directives.</p>
</div></div>
<div class="bottomlang">
-<p><span>Available Languages: </span><a href="../en/rewrite/avoid.html" title="English"> en </a></p>
-</div><div id="footer">
-<p class="apache">Copyright 2010 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>
-<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div>
+<p><span>Available Languages: </span><a href="../en/rewrite/avoid.html" title="English"> en </a> |
+<a href="../fr/rewrite/avoid.html" hreflang="fr" rel="alternate" title="Français"> fr </a></p>
+</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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