rewrite_guide.html

这个是我在web培训时老师提供的手册

        redirection.</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>Use the <code>[NE]</code> flag on the
          <code>RewriteRule</code>. NE stands for No Escape.
          </p>
        </dd>
      </dl>

    </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2>Time-Dependent Rewriting</h2>

      

      <dl>
        <dt>Description:</dt>

        <dd>
          <p>When tricks like time-dependent content should happen a
          lot of webmasters still use CGI scripts which do for
          instance redirects to specialized pages. How can it be done
          via <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>?</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>There are a lot of variables named <code>TIME_xxx</code>
          for rewrite conditions. In conjunction with the special
          lexicographic comparison patterns <code>&lt;STRING</code>,
          <code>&gt;STRING</code>和<code>=STRING</code> we can
          do time-dependent redirects:</p>

<div class="example"><pre>
RewriteEngine on
RewriteCond   %{TIME_HOUR}%{TIME_MIN} &gt;0700
RewriteCond   %{TIME_HOUR}%{TIME_MIN} &lt;1900
RewriteRule   ^foo\.html$             foo.day.html
RewriteRule   ^foo\.html$             foo.night.html
</pre></div>

          <p>This provides the content of <code>foo.day.html</code>
          under the URL <code>foo.html</code> from
          <code>07:00-19:00</code> and at the remaining time the
          contents of <code>foo.night.html</code>. Just a nice
          feature for a homepage...</p>
        </dd>
      </dl>

    </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2>Backward Compatibility for YYYY to XXXX migration</h2>

      

      <dl>
        <dt>Description:</dt>

        <dd>
          <p>How can we make URLs backward compatible (still
          existing virtually) after migrating <code>document.YYYY</code>
          to <code>document.XXXX</code>, e.g. after translating a
          bunch of <code>.html</code> files to <code>.phtml</code>?</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>We just rewrite the name to its basename and test for
          existence of the new extension. If it exists, we take
          that name, else we rewrite the URL to its original state.</p>


<div class="example"><pre>
#   backward compatibility ruleset for
#   rewriting document.html to document.phtml
#   when and only when document.phtml exists
#   but no longer document.html
RewriteEngine on
RewriteBase   /~quux/
#   parse out basename, but remember the fact
RewriteRule   ^(.*)\.html$              $1      [C,E=WasHTML:yes]
#   rewrite to document.phtml if exists
RewriteCond   %{REQUEST_FILENAME}.phtml -f
RewriteRule   ^(.*)$ $1.phtml                   [S=1]
#   else reverse the previous basename cutout
RewriteCond   %{ENV:WasHTML}            ^yes$
RewriteRule   ^(.*)$ $1.html
</pre></div>
        </dd>
      </dl>

    </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="content" id="content">Content Handling</a></h2>

    

    <h3>From Old to New (intern)</h3>

      

      <dl>
        <dt>Description:</dt>

        <dd>
          <p>Assume we have recently renamed the page
          <code>foo.html</code> to <code>bar.html</code> and now want
          to provide the old URL for backward compatibility. Actually
          we want that users of the old URL even not recognize that
          the pages was renamed.</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>We rewrite the old URL to the new one internally via the
          following rule:</p>

<div class="example"><pre>
RewriteEngine  on
RewriteBase    /~quux/
RewriteRule    ^<strong>foo</strong>\.html$  <strong>bar</strong>.html
</pre></div>
        </dd>
      </dl>

    

    <h3>From Old to New (extern)</h3>

      

      <dl>
        <dt>Description:</dt>

        <dd>
          <p>Assume again that we have recently renamed the page
          <code>foo.html</code> to <code>bar.html</code> and now want
          to provide the old URL for backward compatibility. But this
          time we want that the users of the old URL get hinted to
          the new one, i.e. their browsers Location field should
          change, too.</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>We force a HTTP redirect to the new URL which leads to a
          change of the browsers and thus the users view:</p>

<div class="example"><pre>
RewriteEngine  on
RewriteBase    /~quux/
RewriteRule    ^<strong>foo</strong>\.html$  <strong>bar</strong>.html  [<strong>R</strong>]
</pre></div>
        </dd>
      </dl>

    

    <h3>From Static to Dynamic</h3>

      

      <dl>
        <dt>Description:</dt>

        <dd>
          <p>How can we transform a static page
          <code>foo.html</code> into a dynamic variant
          <code>foo.cgi</code> in a seamless way, i.e. without notice
          by the browser/user.</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>We just rewrite the URL to the CGI-script and force the
          correct MIME-type so it gets really run as a CGI-script.
          This way a request to <code>/~quux/foo.html</code>
          internally leads to the invocation of
          <code>/~quux/foo.cgi</code>.</p>

<div class="example"><pre>
RewriteEngine  on
RewriteBase    /~quux/
RewriteRule    ^foo\.<strong>html</strong>$  foo.<strong>cgi</strong>  [T=<strong>application/x-httpd-cgi</strong>]
</pre></div>
        </dd>
      </dl>

    
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="access" id="access">Access Restriction</a></h2>

    

    <h3>Blocking of Robots</h3>

      

      <dl>
        <dt>Description:</dt>

        <dd>
          <p>How can we block a really annoying robot from
          retrieving pages of a specific webarea? A
          <code>/robots.txt</code> file containing entries of the
          "Robot Exclusion Protocol" is typically not enough to get
          rid of such a robot.</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>We use a ruleset which forbids the URLs of the webarea
          <code>/~quux/foo/arc/</code> (perhaps a very deep
          directory indexed area where the robot traversal would
          create big server load). We have to make sure that we
          forbid access only to the particular robot, i.e. just
          forbidding the host where the robot runs is not enough.
          This would block users from this host, too. We accomplish
          this by also matching the User-Agent HTTP header
          information.</p>

<div class="example"><pre>
RewriteCond %{HTTP_USER_AGENT}   ^<strong>NameOfBadRobot</strong>.*
RewriteCond %{REMOTE_ADDR}       ^<strong>123\.45\.67\.[8-9]</strong>$
RewriteRule ^<strong>/~quux/foo/arc/</strong>.+   -   [<strong>F</strong>]
</pre></div>
        </dd>
      </dl>

    

    <h3>Blocked Inline-Images</h3>

      

      <dl>
        <dt>Description:</dt>

        <dd>
          <p>Assume we have under <code>http://www.quux-corp.de/~quux/</code>
          some pages with inlined GIF graphics. These graphics are
          nice, so others directly incorporate them via hyperlinks to
          their pages. We don't like this practice because it adds
          useless traffic to our server.</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>While we cannot 100% protect the images from inclusion,
          we can at least restrict the cases where the browser
          sends a HTTP Referer header.</p>

<div class="example"><pre>
RewriteCond %{HTTP_REFERER} <strong>!^$</strong>
RewriteCond %{HTTP_REFERER} !^http://www.quux-corp.de/~quux/.*$ [NC]
RewriteRule <strong>.*\.gif$</strong>        -                                    [F]
</pre></div>

<div class="example"><pre>
RewriteCond %{HTTP_REFERER}         !^$
RewriteCond %{HTTP_REFERER}         !.*/foo-with-gif\.html$
RewriteRule <strong>^inlined-in-foo\.gif$</strong>   -                        [F]
</pre></div>
        </dd>
      </dl>

    

    <h3>Proxy Deny</h3>

      

      <dl>
        <dt>Description:</dt>

        <dd>
          <p>How can we forbid a certain host or even a user of a
          special host from using the Apache proxy?</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>We first have to make sure <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>
          is below(!) <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> in the Configuration
          file when compiling the Apache webserver. This way it gets
          called <em>before</em> <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>. Then we
          configure the following for a host-dependent deny...</p>

<div class="example"><pre>
RewriteCond %{REMOTE_HOST} <strong>^badhost\.mydomain\.com$</strong>
RewriteRule !^http://[^/.]\.mydomain.com.*  - [F]
</pre></div>

          <p>...and this one for a user@host-dependent deny:</p>

<div class="example"><pre>
RewriteCond %{REMOTE_IDENT}@%{REMOTE_HOST}  <strong>^badguy@badhost\.mydomain\.com$</strong>
RewriteRule !^http://[^/.]\.mydomain.com.*  - [F]
</pre></div>
        </dd>
      </dl>

    

  </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="other" id="other">Other</a></h2>

    

    <h3>External Rewriting Engine</h3>

      

      <dl>
        <dt>Description:</dt>

        <dd>
          <p>A FAQ: How can we solve the FOO/BAR/QUUX/etc.
          problem? There seems no solution by the use of
          <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>...</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>Use an external <code class="directive"><a href="../mod/mod_rewrite.html#rewritemap">RewriteMap</a></code>, i.e. a program which acts
          like a <code class="directive"><a href="../mod/mod_rewrite.html#rewritemap">RewriteMap</a></code>. It is run once on startup of Apache
          receives the requested URLs on <code>STDIN</code> and has
          to put the resulting (usually rewritten) URL on
          <code>STDOUT</code> (same order!).</p>

<div class="example"><pre>
RewriteEngine on
RewriteMap    quux-map       <strong>prg:</strong>/path/to/map.quux.pl
RewriteRule   ^/~quux/(.*)$  /~quux/<strong>${quux-map:$1}</strong>
</pre></div>

<div class="example"><pre>
#!/path/to/perl

#   disable buffered I/O which would lead
#   to deadloops for the Apache server
$| = 1;

#   read URLs one per line from stdin and
#   generate substitution URL on stdout
while (&lt;&gt;) {
    s|^foo/|bar/|;
    print $_;
}
</pre></div>

          <p>This is a demonstration-only example and just rewrites
          all URLs <code>/~quux/foo/...</code> to
          <code>/~quux/bar/...</code>. Actually you can program
          whatever you like. But notice that while such maps can be
          <strong>used</strong> also by an average user, only the
          system administrator can <strong>define</strong> it.</p>
        </dd>
      </dl>

    

  </div></div>
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