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Subject svn commit: r1308341 - /httpd/httpd/branches/2.2.x/docs/manual/mod/mod_rewrite.xml
Date Mon, 02 Apr 2012 13:17:17 GMT
Author: covener
Date: Mon Apr  2 13:17:16 2012
New Revision: 1308341

backport r1308327 from trunk -- clarify RewriteBase example/info


Modified: httpd/httpd/branches/2.2.x/docs/manual/mod/mod_rewrite.xml
--- httpd/httpd/branches/2.2.x/docs/manual/mod/mod_rewrite.xml (original)
+++ httpd/httpd/branches/2.2.x/docs/manual/mod/mod_rewrite.xml Mon Apr  2 13:17:16 2012
@@ -561,96 +561,48 @@ once!
 <description>Sets the base URL for per-directory rewrites</description>
 <syntax>RewriteBase <em>URL-path</em></syntax>
-<default>See usage for information.</default>
-      <p>The <directive>RewriteBase</directive> directive explicitly
-      sets the base URL for per-directory rewrites. As you will see
-      below, <directive module="mod_rewrite">RewriteRule</directive>
-      can be used in per-directory config files
-      (<code>.htaccess</code>). In such a case, it will act locally,
-      stripping the local directory prefix before processing, and applying
-      rewrite rules only to the remainder. When processing is complete, the 
-      prefix is automatically added back to the
-      path. The default setting is; <directive>RewriteBase</directive> <em>physical-directory-path</em></p>
-      <p>When a substitution occurs for a new URL, this module has
-      to re-inject the URL into the server processing. To be able
-      to do this it needs to know what the corresponding URL-prefix
-      or URL-base is. By default this prefix is the corresponding
-      filepath itself. <strong>However, for most websites, URLs are NOT
-      directly related to physical filename paths, so this
-      assumption will often be wrong!</strong> Therefore, you can 
-      use the <code>RewriteBase</code> directive to specify the
-      correct URL-prefix.</p>
-<note> If your webserver's URLs are <strong>not</strong> directly
-related to physical file paths, you will need to use
-<directive>RewriteBase</directive> in every <code>.htaccess</code>
-file where you want to use <directive
-module="mod_rewrite">RewriteRule</directive> directives.
-        <p> For example, assume the following per-directory config file:</p>
+      <p>The <directive>RewriteBase</directive> directive specifies the
+      URL prefix to be used for per-directory (htaccess) 
+      <directive>RewriteRule</directive> directives that substitute a relative
+      path.</p>
+      <p> This directive is <em>required</em> when you use a relative path
+      in a substitution in per-directory (htaccess) context unless either
+      of the following conditions are true:
+      <ul>
+          <li> The original request, and the substitution, are underneath the 
+               <directive module="core">DocumentRoot</directive>
+               (as opposed to reachable by other means, such as 
+               <directive module="mod_alias">Alias</directive>).</li>
+          <li> The <em>filesystem</em> path to the directory containing
+               <directive>RewriteRule</directive>, suffixed by the relative 
+               substitution is also valid as a URL path on the server 
+               (this is rare).</li>
+      </ul>
+      </p>
+<p> In the example below, <directive>RewriteBase</directive> is necessary
+    to avoid rewriting to
+    since the resource was not relative to the document root.  This 
+    misconfiguration would normally cause the server to look for an "opt"
+    directory under the document root.</p>
-#  /abc/def/.htaccess -- per-dir config file for directory /abc/def
-#  Remember: /abc/def is the physical path of /xyz, <em>i.e.</em>, the server
-#            has a 'Alias /xyz /abc/def' directive <em>e.g.</em>
+DocumentRoot /var/www/
+Alias /myapp /opt/myapp-1.2.3
+&lt;Directory /opt/myapp-1.2.3&gt;
 RewriteEngine On
-#  let the server know that we were reached via /xyz and not
-#  via the physical path prefix /abc/def
-RewriteBase   /xyz
-#  now the rewriting rules
-RewriteRule   ^oldstuff\.html$  newstuff.html
+RewriteBase /myapp/
+RewriteRule ^index\.html$  welcome.html 
-        <p>In the above example, a request to
-        <code>/xyz/oldstuff.html</code> gets correctly rewritten to
-        the physical file <code>/abc/def/newstuff.html</code>.</p>
-<note><title>For Apache Hackers</title>
-<p>The following list gives detailed information about
-              the internal processing steps:</p>
-  /xyz/oldstuff.html
-Internal Processing:
-  /xyz/oldstuff.html     -&gt; /abc/def/oldstuff.html  (per-server Alias)
-  /abc/def/oldstuff.html -&gt; /abc/def/newstuff.html  (per-dir    RewriteRule)
-  /abc/def/newstuff.html -&gt; /xyz/newstuff.html      (per-dir    RewriteBase)
-  /xyz/newstuff.html     -&gt; /abc/def/newstuff.html  (per-server Alias)
-  /abc/def/newstuff.html
-              <p>This seems very complicated, but is in fact
-              correct Apache internal processing. Because the
-              per-directory rewriting comes late in the
-              process, the rewritten request
-              has to be re-injected into the Apache kernel, as if it
-              were a new request. (See <a
-              href="../rewrite/tech.html">mod_rewrite technical
-              details</a>.)
-              This is not the serious overhead it may seem to be - 
-              this re-injection is completely internal to the 
-	      Apache server (and the same procedure is used by 
-	      many other operations within Apache).</p> 

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