1<?xml version="1.0" encoding="ISO-8859-1"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!-- 4 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 5 This file is generated from xml source: DO NOT EDIT 6 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 7 --> 8<title>When not to use mod_rewrite - Apache HTTP Server</title> 9<link href="/style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /> 10<link href="/style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /> 11<link href="/style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="/style/css/prettify.css" /> 12<script src="/style/scripts/prettify.min.js" type="text/javascript"> 13</script> 14 15<link href="/images/favicon.ico" rel="shortcut icon" /></head> 16<body id="manual-page"><div id="page-header"> 17<p class="menu"><a href="/mod/">Modules</a> | <a href="/mod/directives.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> 18<p class="apache">Apache HTTP Server Version 2.4</p> 19<img alt="" src="/images/feather.gif" /></div> 20<div class="up"><a href="./"><img title="<-" alt="<-" src="/images/left.gif" /></a></div> 21<div id="path"> 22<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.4</a> > <a href="./">Rewrite</a></div><div id="page-content"><div id="preamble"><h1>When not to use mod_rewrite</h1> 23<div class="toplang"> 24<p><span>Available Languages: </span><a href="/en/rewrite/avoid.html" title="English"> en </a> | 25<a href="/fr/rewrite/avoid.html" hreflang="fr" rel="alternate" title="Fran�ais"> fr </a></p> 26</div> 27 28 29<p>This document supplements the <code class="module"><a href="/mod/mod_rewrite.html">mod_rewrite</a></code> 30<a href="/mod/mod_rewrite.html">reference documentation</a>. It describes 31perhaps one of the most important concepts about mod_rewrite - namely, 32when to avoid using it.</p> 33 34<p>mod_rewrite should be considered a last resort, when other 35alternatives are found wanting. Using it when there are simpler 36alternatives leads to configurations which are confusing, fragile, and 37hard to maintain. Understanding what other alternatives are available is 38a very important step towards mod_rewrite mastery.</p> 39 40<p>Note that many of these examples won't work unchanged in your 41particular server configuration, so it's important that you understand 42them, rather than merely cutting and pasting the examples into your 43configuration.</p> 44 45<p>The most common situation in which <code class="module"><a href="/mod/mod_rewrite.html">mod_rewrite</a></code> is 46the right tool is when the very best solution requires access to the 47server configuration files, and you don't have that access. Some 48configuration directives are only available in the server configuration 49file. So if you are in a hosting situation where you only have .htaccess 50files to work with, you may need to resort to 51<code class="module"><a href="/mod/mod_rewrite.html">mod_rewrite</a></code>.</p> 52 53</div> 54<div id="quickview"><ul id="toc"><li><img alt="" src="/images/down.gif" /> <a href="#redirect">Simple Redirection</a></li> 55<li><img alt="" src="/images/down.gif" /> <a href="#alias">URL Aliasing</a></li> 56<li><img alt="" src="/images/down.gif" /> <a href="#vhosts">Virtual Hosting</a></li> 57<li><img alt="" src="/images/down.gif" /> <a href="#proxy">Simple Proxying</a></li> 58<li><img alt="" src="/images/down.gif" /> <a href="#setenv">Environment Variable Testing</a></li> 59</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></ul><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div> 60<div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 61<div class="section"> 62<h2><a name="redirect" id="redirect">Simple Redirection</a></h2> 63 64 65<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 66means to redirect one URL to another. This kind of simple redirection of 67one URL, or a class of URLs, to somewhere else, should be accomplished 68using these directives rather than <code class="directive"><a href="/mod/mod_rewrite.html#rewriterule">RewriteRule</a></code>. <code>RedirectMatch</code> 69allows you to include a regular expression in your redirection criteria, 70providing many of the benefits of using <code>RewriteRule</code>.</p> 71 72<p>A common use for <code>RewriteRule</code> is to redirect an entire 73class of URLs. For example, all URLs in the <code>/one</code> directory 74must be redirected to <code>http://one.example.com/</code>, or perhaps 75all <code>http</code> requests must be redirected to 76<code>https</code>.</p> 77 78<p>These situations are better handled by the <code>Redirect</code> 79directive. Remember that <code>Redirect</code> preserves path 80information. That is to say, a redirect for a URL <code>/one</code> will 81also redirect all URLs under that, such as <code>/one/two.html</code> 82and <code>/one/three/four.html</code>.</p> 83 84<p>To redirect URLs under <code>/one</code> to 85<code>http://one.example.com</code>, do the following:</p> 86 87<pre class="prettyprint lang-config">Redirect /one/ http://one.example.com/</pre> 88 89 90<p>To redirect <code>http</code> URLs to <code>https</code>, do the 91following:</p> 92 93<pre class="prettyprint lang-config"><VirtualHost *:80> 94 ServerName www.example.com 95 Redirect / https://www.example.com/ 96</VirtualHost > 97 98<VirtualHost *:443> 99 ServerName www.example.com 100 # ... SSL configuration goes here 101</VirtualHost ></pre> 102 103 104<p>The use of <code>RewriteRule</code> to perform this task may be 105appropriate if there are other <code>RewriteRule</code> directives in 106the same scope. This is because, when there are <code>Redirect</code> 107and <code>RewriteRule</code> directives in the same scope, the 108<code>RewriteRule</code> directives will run first, regardless of the 109order of appearance in the configuration file.</p> 110 111<p>In the case of the <em>http-to-https</em> redirection, the use of 112<code>RewriteRule</code> would be appropriate if you don't have access 113to the main server configuration file, and are obliged to perform this 114task in a <code>.htaccess</code> file instead.</p> 115 116</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 117<div class="section"> 118<h2><a name="alias" id="alias">URL Aliasing</a></h2> 119<p>The <code class="directive"><a href="/mod/mod_alias.html#alias">Alias</a></code> directive 120provides mapping from a URI to a directory - usually a directory outside 121of your <code class="directive"><a href="/mod/core.html#documentroot">DocumentRoot</a></code>. Although it 122is possible to perform this mapping with <code>mod_rewrite</code>, 123<code>Alias</code> is the preferred method, for reasons of simplicity 124and performance.</p> 125 126<div class="example"><h3>Using Alias</h3><pre class="prettyprint lang-config">Alias /cats /var/www/virtualhosts/felines/htdocs</pre> 127</div> 128 129<p> 130The use of <code>mod_rewrite</code> to perform this mapping may be 131appropriate when you do not have access to the server configuration 132files. Alias may only be used in server or virtualhost context, and not 133in a <code>.htaccess</code> file. 134</p> 135 136<p>Symbolic links would be another way to accomplish the same thing, if 137you have <code>Options FollowSymLinks</code> enabled on your 138server.</p> 139</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 140<div class="section"> 141<h2><a name="vhosts" id="vhosts">Virtual Hosting</a></h2> 142<p>Although it is possible to handle <a href="vhosts.html">virtual hosts 143with mod_rewrite</a>, it is seldom the right way. Creating individual 144<VirtualHost> blocks is almost always the right way to go. In the 145event that you have an enormous number of virtual hosts, consider using 146<code class="module"><a href="/mod/mod_vhost_alias.html">mod_vhost_alias</a></code> to create these hosts automatically.</p> 147 148<p>Modules such as <code class="module"><a href="/mod/mod_macro.html">mod_macro</a></code> are 149also useful for creating a large number of virtual hosts dynamically.</p> 150 151<p>Using <code class="module"><a href="/mod/mod_rewrite.html">mod_rewrite</a></code> for vitualhost creation may be 152appropriate if you are using a hosting service that does not provide 153you access to the server configuration files, and you are therefore 154restricted to configuration using <code>.htaccess</code> files.</p> 155 156<p>See the <a href="vhosts.html">virtual hosts with mod_rewrite</a> 157document for more details on how you might accomplish this if it still 158seems like the right approach.</p> 159 160</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 161<div class="section"> 162<h2><a name="proxy" id="proxy">Simple Proxying</a></h2> 163 164<p><code>RewriteRule</code> provides the <a href="flags.html#flag_p">[P]</a> flag to pass rewritten URIs through 165<code class="module"><a href="/mod/mod_proxy.html">mod_proxy</a></code>.</p> 166 167<pre class="prettyprint lang-config">RewriteRule ^/?images(.*) http://imageserver.local/images$1 [P]</pre> 168 169 170<p>However, in many cases, when there is no actual pattern matching 171needed, 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. 172The example here could be rendered as:</p> 173 174<pre class="prettyprint lang-config">ProxyPass /images/ http://imageserver.local/images/</pre> 175 176 177<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 178<code class="directive"><a href="/mod/mod_proxy.html#proxypassreverse">ProxyPassReverse</a></code> directive to 179catch redirects issued from the back-end server:</p> 180 181<pre class="prettyprint lang-config">ProxyPassReverse /images/ http://imageserver.local/images/</pre> 182 183 184<p>You may need to use <code>RewriteRule</code> instead when there are 185other <code>RewriteRule</code>s in effect in the same scope, as a 186<code>RewriteRule</code> will usually take effect before a 187<code>ProxyPass</code>, and so may preempt what you're trying to 188accomplish.</p> 189 190</div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 191<div class="section"> 192<h2><a name="setenv" id="setenv">Environment Variable Testing</a></h2> 193 194<p><code class="module"><a href="/mod/mod_rewrite.html">mod_rewrite</a></code> is frequently used to take a particular 195action based on the presence or absence of a particular environment 196variable or request header. This can be done more efficiently using the 197<code class="directive"><a href="/mod/core.html#if"><If></a></code>.</p> 198 199<p>Consider, for example, the common scenario where 200<code class="directive">RewriteRule</code> is used to enforce a canonical 201hostname, such as <code>www.example.com</code> instead of 202<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> 203 204<pre class="prettyprint lang-config"><If "req('Host') != 'www.example.com'"> 205 Redirect / http://www.example.com/ 206</If></pre> 207 208 209<p>This technique can be used to take actions based on any request 210header, response header, or environment variable, replacing 211<code class="module"><a href="/mod/mod_rewrite.html">mod_rewrite</a></code> in many common scenarios.</p> 212 213<p>See especially the <a href="/expr.html">expression evaluation 214documentation</a> for a overview of what types of expressions you can 215use in <If> sections, and in certain other directives.</p> 216 217</div></div> 218<div class="bottomlang"> 219<p><span>Available Languages: </span><a href="/en/rewrite/avoid.html" title="English"> en </a> | 220<a href="/fr/rewrite/avoid.html" hreflang="fr" rel="alternate" title="Fran�ais"> fr </a></p> 221</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. 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