rewrite_intro.html.en

Apache官方在今天放出产品系列2.2的最新版本2.2.11的源码包 最流行的HTTP服务器软件之一

<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">&lt;Directory&gt;</a></code> section) or
inside <code class="directive"><a href="../mod/core.html#virtualhost">&lt;VirtualHost&gt;</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">&lt;Directory&gt;</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>

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