diff options
| author | Rich Bowen <rbowen@apache.org> | 2009-11-02 19:31:08 +0100 |
|---|---|---|
| committer | Rich Bowen <rbowen@apache.org> | 2009-11-02 19:31:08 +0100 |
| commit | d2b36fc6aa4a8245fe003c7576caedaa370f8931 (patch) | |
| tree | 3a031ed06fc52e5dff61f051759a5aa2f84751d1 /docs/manual/rewrite/intro.html.en | |
| parent | Rewrite of the overview/introduction for this section of the docs. (diff) | |
| download | apache2-d2b36fc6aa4a8245fe003c7576caedaa370f8931.tar.xz apache2-d2b36fc6aa4a8245fe003c7576caedaa370f8931.zip | |
As discussed on the docs mailing list several months back, we're
removing the 'rewrite_' from the various files in the rewrite/
directory, since it's redundant. This change moves rewrite_intro to
intro. Patches to follow will rename the other rewrite_ files.
git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@832009 13f79535-47bb-0310-9956-ffa450edef68
Diffstat (limited to 'docs/manual/rewrite/intro.html.en')
| -rw-r--r-- | docs/manual/rewrite/intro.html.en | 319 |
1 files changed, 319 insertions, 0 deletions
diff --git a/docs/manual/rewrite/intro.html.en b/docs/manual/rewrite/intro.html.en new file mode 100644 index 0000000000..e648627136 --- /dev/null +++ b/docs/manual/rewrite/intro.html.en @@ -0,0 +1,319 @@ +<?xml version="1.0" encoding="ISO-8859-1"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!-- + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + This file is generated from xml source: DO NOT EDIT + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + --> +<title>Apache mod_rewrite Introduction - Apache HTTP Server</title> +<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /> +<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /> +<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /> +<link href="../images/favicon.ico" rel="shortcut icon" /></head> +<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> +<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>Apache mod_rewrite Introduction</h1> +<div class="toplang"> +<p><span>Available Languages: </span><a href="../en/rewrite/intro.html" title="English"> en </a> | +<a href="../fr/rewrite/intro.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> +<a href="../mod/mod_rewrite.html">reference documentation</a>. It +describes the basic concepts necessary for use of +<code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>. Other documents go into greater detail, +but this doc should help the beginner get their feet wet. +</p> +</div> +<div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#introduction">Introduction</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#regex">Regular Expressions</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#rewriterule">RewriteRule basics</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#flags">Rewrite Flags</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#rewritecond">Rewrite conditions</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#rewritemap">Rewrite maps</a></li> +<li><img alt="" src="../images/down.gif" /> <a href="#htaccess">.htaccess files</a></li> +</ul><h3>See also</h3><ul class="seealso"><li><a href="../mod/mod_rewrite.html">Module +documentation</a></li><li><a href="rewrite_tech.html">Technical details</a></li><li><a href="rewrite_guide.html">Practical solutions to common +problems</a></li><li><a href="rewrite_guide_advanced.html">Practical solutions to +advanced problems</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="introduction" id="introduction">Introduction</a></h2> +<p>The Apache module <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> is a very powerful and +sophisticated module which provides a way to do URL manipulations. With +it, you can do nearly all types of URL rewriting that you may need. It +is, however, somewhat complex, and may be intimidating to the beginner. +There is also a tendency to treat rewrite rules as magic incantation, +using them without actually understanding what they do.</p> + +<p>This document attempts to give sufficient background so that what +follows is understood, rather than just copied blindly. +</p> + +<p>Remember that many common URL-manipulation tasks don't require the +full power and complexity of <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>. For simple +tasks, see <code class="module"><a href="../mod/mod_alias.html">mod_alias</a></code> and the documentation +on <a href="../urlmapping.html">mapping URLs to the +filesystem</a>.</p> + +<p>Finally, before proceeding, be sure to configure +the <code class="directive"><a href="../mod/mod_rewrite.html#rewritelog">RewriteLog</a></code>. Although +this log file can give an overwhelming amount of information, it is +indispensable in debugging problems with <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> +configuration, since it will tell you exactly how each rule is +processed.</p> + +<div class="note"> +<p>The RewriteLog directive cannot be used in .htaccess files, but can +only be set in the main server configuration file.</p> +</div> +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="regex" id="regex">Regular Expressions</a></h2> + +<p>mod_rewrite uses the <a href="http://pcre.org/">Perl Compatible +Regular Expression</a> vocabulary. In this document, we do not attempt +to provide a detailed reference to regular expressions. For that, we +recommend the <a href="http://pcre.org/pcre.txt">PCRE man pages</a>, the +<a href="http://perldoc.perl.org/perlre.html">Perl regular +expression man page</a>, and <a href="http://www.oreilly.com/catalog/regex2/index.html">Mastering +Regular Expressions, by Jeffrey Friedl</a>.</p> + +<p>In this document, we attempt to provide enough of a regex vocabulary +to get you started, without being overwhelming, in the hope that +<code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code>s will be scientific +formulae, rather than magical incantations.</p> + +<h3><a name="regexvocab" id="regexvocab">Regex vocabulary</a></h3> + +<p>The following are the minimal building blocks you will need, in order +to write regular expressions and <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code>s. They certainly do not +represent a complete regular expression vocabulary, but they are a good +place to start, and should help you read basic regular expressions, as +well as write your own.</p> + +<table> +<tr> +<th>Character</th> +<th>Meaning</th> +<th>Example</th> +</tr> + +<tr><td><code>.</code></td><td>Matches any single +character</td><td><code>c.t</code> will match <code>cat</code>, +<code>cot</code>, <code>cut</code>, etc.</td></tr> +<tr><td><code>+</code></td><td>Repeats the previous match one or more +times</td><td><code>a+</code> matches <code>a</code>, <code>aa</code>, +<code>aaa</code>, etc</td></tr> +<tr><td><code>*</code></td><td>Repeats the previous match zero or more +times.</td><td><code>a*</code> matches all the same things +<code>a+</code> matches, but will also match an empty string.</td></tr> +<tr><td><code>?</code></td><td>Makes the match optional.</td><td> +<code>colou?r</code> will match <code>color</code> and <code>colour</code>.</td> +</tr> +<tr><td><code>^</code></td><td>Called an anchor, matches the beginning +of the string</td><td><code>^a</code> matches a string that begins with +<code>a</code></td></tr> +<tr><td><code>$</code></td><td>The other anchor, this matches the end of +the string.</td><td><code>a$</code> matches a string that ends with +<code>a</code>.</td></tr> +<tr><td><code>( )</code></td><td>Groups several characters into a single +unit, and captures a match for use in a backreference.</td><td><code>(ab)+</code> +matches <code>ababab</code> - that is, the <code>+</code> applies to the group. +For more on backreferences see <a href="#InternalBackRefs">below</a>.</td></tr> +<tr><td><code>[ ]</code></td><td>A character class - matches one of the +characters</td><td><code>c[uoa]t</code> matches <code>cut</code>, +<code>cot</code> or <code>cat</code>.</td></tr> +<tr><td><code>[^ ]</code></td><td>Negative character class - matches any character not specified</td><td><code>c[^/]t</code> matches <code>cat</code> or <code>c=t</code> but not <code>c/t</code></td></tr> +</table> + +<p>In <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> the <code>!</code> character can be +used before a regular expression to negate it. This is, a string will +be considered to have matched only if it does not match the rest of +the expression.</p> + + + +<h3><a name="InternalBackRefs" id="InternalBackRefs">Regex Back-Reference Availability</a></h3> + + <p>One important thing here has to be remembered: Whenever you + use parentheses in <em>Pattern</em> or in one of the + <em>CondPattern</em>, back-references are internally created + which can be used with the strings <code>$N</code> and + <code>%N</code> (see below). These are available for creating + the strings <em>Substitution</em> and <em>TestString</em>. + Figure 2 shows to which locations the back-references are + transferred for expansion.</p> + +<p class="figure"> + <img src="../images/mod_rewrite_fig2.gif" width="381" height="179" alt="[Needs graphics capability to display]" /><br /> + <dfn>Figure 2:</dfn> The back-reference flow through a rule. +</p> + + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="rewriterule" id="rewriterule">RewriteRule basics</a></h2> +<p>A <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> consists +of three arguments separated by spaces. The arguments are</p> +<ol> +<li><var>Pattern</var>: which incoming URLs should be affected by the rule;</li> +<li><var>Substitution</var>: where should the matching requests be sent;</li> +<li><var>[flags]</var>: options affecting the rewritten request.</li> +</ol> + +<p>The <var>Pattern</var> is always a <a href="#regex">regular +expression</a> matched against the URL-Path of the incoming request +(the part after the hostname but before any question mark indicating +the beginning of a query string).</p> + +<p>The <var>Substitution</var> can itself be one of three things:</p> + +<dl> +<dt>A full filesystem path to a resource</dt> +<dd> +<div class="example"><p><code> +RewriteRule ^/games.* /usr/local/games/web +</code></p></div> +<p>This maps a request to an arbitrary location on your filesystem, much +like the <code class="directive"><a href="../mod/mod_alias.html#alias">Alias</a></code> directive.</p> +</dd> + +<dt>A web-path to a resource</dt> +<dd> +<div class="example"><p><code> +RewriteRule ^/foo$ /bar +</code></p></div> +<p>If <code class="directive"><a href="../mod/core.html#documentroot">DocumentRoot</a></code> is set +to <code>/usr/local/apache2/htdocs</code>, then this directive would +map requests for <code>http://example.com/foo</code> to the +path <code>/usr/local/apache2/htdocs/bar</code>.</p> +</dd> + +<dt>An absolute URL</dt> +<dd> +<div class="example"><p><code> +RewriteRule ^/product/view$ http://site2.example.com/seeproduct.html [R] +</code></p></div> +<p>This tells the client to make a new request for the specified URL.</p> +</dd> +</dl> + +<p>The <var>Substitution</var> can also +contain <em>back-references</em> to parts of the incoming URL-path +matched by the <var>Pattern</var>. Consider the following:</p> +<div class="example"><p><code> +RewriteRule ^/product/(.*)/view$ /var/web/productdb/$1 +</code></p></div> +<p>The variable <code>$1</code> will be replaced with whatever text +was matched by the expression inside the parenthesis in +the <var>Pattern</var>. For example, a request +for <code>http://example.com/product/r14df/view</code> will be mapped +to the path <code>/var/web/productdb/r14df</code>.</p> + +<p>If there is more than one expression in parenthesis, they are +available in order in the +variables <code>$1</code>, <code>$2</code>, <code>$3</code>, and so +on.</p> + + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="flags" id="flags">Rewrite Flags</a></h2> +<p>The behavior of a <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> can be modified by the +application of one or more flags to the end of the rule. For example, the +matching behavior of a rule can be made case-insensitive by the +application of the <code>[NC]</code> flag: +</p> +<div class="example"><p><code> +RewriteRule ^puppy.html smalldog.html [NC] +</code></p></div> + +<p>For more details on the available flags, their meanings, and +examples, see the <a href="rewrite_flags.html">Rewrite Flags</a> document.</p> + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="rewritecond" id="rewritecond">Rewrite conditions</a></h2> +<p>One or more <code class="directive"><a href="../mod/mod_rewrite.html#rewritecond">RewriteCond</a></code> +directives can be used to restrict the types of requests that will be +subject to the +following <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code>. The +first argument is a variable describing a characteristic of the +request, the second argument is a <a href="#regex">regular +expression</a> that must match the variable, and a third optional +argument is a list of flags that modify how the match is evaluated.</p> + +<p>For example, to send all requests from a particular IP range to a +different server, you could use:</p> +<div class="example"><p><code> +RewriteCond %{REMOTE_ADDR} ^10\.2\.<br /> +RewriteRule (.*) http://intranet.example.com$1 +</code></p></div> + +<p>When more than +one <code class="directive"><a href="../mod/mod_rewrite.html#rewritecond">RewriteCond</a></code> is +specified, they must all match for +the <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> to be +applied. For example, to deny requests that contain the word "hack" in +their query string, except if they also contain a cookie containing +the word "go", you could use:</p> +<div class="example"><p><code> +RewriteCond %{QUERY_STRING} hack<br /> +RewriteCond %{HTTP_COOKIE} !go<br /> +RewriteRule .* - [F] +</code></p></div> +<p>Notice that the exclamation mark specifies a negative match, so the rule is only applied if the cookie does not contain "go".</p> + +<p>Matches in the regular expressions contained in +the <code class="directive"><a href="../mod/mod_rewrite.html#rewritecond">RewriteCond</a></code>s can be +used as part of the <var>Substitution</var> in +the <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> using the +variables <code>%1</code>, <code>%2</code>, etc. For example, this +will direct the request to a different directory depending on the +hostname used to access the site:</p> +<div class="example"><p><code> +RewriteCond %{HTTP_HOST} (.*)<br /> +RewriteRule ^/(.*) /sites/%1/$1 +</code></p></div> +<p>If the request was for <code>http://example.com/foo/bar</code>, +then <code>%1</code> would contain <code>example.com</code> +and <code>$1</code> would contain <code>foo/bar</code>.</p> + + + +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="rewritemap" id="rewritemap">Rewrite maps</a></h2> +<p>See <code class="directive"><a href="../mod/mod_rewrite.html#rewritemap">RewriteMap</a></code>.</p> +</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="htaccess" id="htaccess">.htaccess files</a></h2> + +<p>Rewriting is typically configured in the main server configuration +setting (outside any <code class="directive"><a href="../mod/core.html#directory"><Directory></a></code> section) or +inside <code class="directive"><a href="../mod/core.html#virtualhost"><VirtualHost></a></code> +containers. This is the easiest way to do rewriting and is +recommended. It is possible, however, to do rewriting +inside <code class="directive"><a href="../mod/core.html#directory"><Directory></a></code> +sections or <a href="../howto/htaccess.html"><code>.htaccess</code> +files</a> at the expense of some additional complexity. This technique +is called per-directory rewrites.</p> + +<p>The main difference with per-server rewrites is that the path +prefix of the directory containing the <code>.htaccess</code> file is +stripped before matching in +the <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code>. In addition, the <code class="directive"><a href="../mod/mod_rewrite.html#rewritebase">RewriteBase</a></code> should be used to assure the request is properly mapped.</p> + +</div></div> +<div class="bottomlang"> +<p><span>Available Languages: </span><a href="../en/rewrite/intro.html" title="English"> en </a> | +<a href="../fr/rewrite/intro.html" hreflang="fr" rel="alternate" title="Français"> fr </a></p> +</div><div id="footer"> +<p class="apache">Copyright 2009 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> +</body></html>
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