mod_rewrite.html.en

Apache HTTP Server 是一个功能强大的灵活的与HTTP/1.1相兼容的web服务器.这里给出的是Apache HTTP服务器的源码。

                  include/ap_mmn.h. The module API version
                  corresponds to the version of Apache in use (in
                  the release version of Apache 1.3.14, for
                  instance, it is 19990320:10), but is mainly of
                  interest to module authors.</dd>

                  <dt><code>THE_REQUEST</code></dt>

                  <dd>The full HTTP request line sent by the
                  browser to the server (e.g., "<code>GET
                  /index.html HTTP/1.1</code>"). This does not
                  include any additional headers sent by the
                  browser.</dd>

                  <dt><code>REQUEST_URI</code></dt>

                  <dd>The resource requested in the HTTP request
                  line. (In the example above, this would be
                  "/index.html".)</dd>

                  <dt><code>REQUEST_FILENAME</code></dt>

                  <dd>The full local filesystem path to the file or
                  script matching the request.</dd>

                  <dt><code>HTTPS</code></dt>

                  <dd>Will contain the text "on" if the connection is
                  using SSL/TLS, or "off" otherwise.  (This variable
                  can be safely used regardless of whether
                  <code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code> is loaded).</dd>

                </dl>
</div>
        </li>
      </ul>

      <p>Special Notes:</p>

      <ol>
        <li>The variables SCRIPT_FILENAME and REQUEST_FILENAME
        contain the same value, <em>i.e.</em>, the value of the
        <code>filename</code> field of the internal
        <code>request_rec</code> structure of the Apache server.
        The first name is just the commonly known CGI variable name
        while the second is the consistent counterpart to
        REQUEST_URI (which contains the value of the
        <code>uri</code> field of <code>request_rec</code>).</li>

        <li>There is the special format:
        <code>%{ENV:variable}</code> where <em>variable</em> can be
        any environment variable. This is looked-up via internal
        Apache structures and (if not found there) via
        <code>getenv()</code> from the Apache server process.</li>

        <li>There is the special format: 
        <code>%{SSL:variable}</code> where <em>variable</em> is the
        name of an <a href="mod_ssl.html#envvars">SSL environment
        variable</a>; this can be used whether or not
        <code class="module"><a href="../mod/mod_ssl.html">mod_ssl</a></code> is loaded, but will always expand to
        the empty string if it is not.  Example:
        <code>%{SSL:SSL_CIPHER_USEKEYSIZE}</code> may expand to
        <code>128</code>.</li>

        <li>There is the special format:
        <code>%{HTTP:header}</code> where <em>header</em> can be
        any HTTP MIME-header name. This is looked-up from the HTTP
        request. Example: <code>%{HTTP:Proxy-Connection}</code> is
        the value of the HTTP header
        ``<code>Proxy-Connection:</code>''.</li>

        <li>There is the special format
        <code>%{LA-U:variable}</code> for look-aheads which perform
        an internal (URL-based) sub-request to determine the final
        value of <em>variable</em>. Use this when you want to use a
        variable for rewriting which is actually set later in an
        API phase and thus is not available at the current stage.
        For instance when you want to rewrite according to the
        <code>REMOTE_USER</code> variable from within the
        per-server context (<code>httpd.conf</code> file) you have
        to use <code>%{LA-U:REMOTE_USER}</code> because this
        variable is set by the authorization phases which come
        <em>after</em> the URL translation phase where mod_rewrite
        operates. On the other hand, because mod_rewrite implements
        its per-directory context (<code>.htaccess</code> file) via
        the Fixup phase of the API and because the authorization
        phases come <em>before</em> this phase, you just can use
        <code>%{REMOTE_USER}</code> there.</li>

        <li>There is the special format:
        <code>%{LA-F:variable}</code> which performs an internal
        (filename-based) sub-request to determine the final value
        of <em>variable</em>. Most of the time this is the same as
        LA-U above.</li>
      </ol>

      <p><em>CondPattern</em> is the condition pattern,
      <em>i.e.</em>, a regular expression which is applied to the
      current instance of the <em>TestString</em>, <em>i.e.</em>,
      <em>TestString</em> is evaluated and then matched against
      <em>CondPattern</em>.</p>

      <p><strong>Remember:</strong> <em>CondPattern</em> is a
      <em>perl compatible regular expression</em> with some
      additions:</p>

      <ol>
        <li>You can prefix the pattern string with a
        '<code>!</code>' character (exclamation mark) to specify a
        <strong>non</strong>-matching pattern.</li>

        <li>
          There are some special variants of <em>CondPatterns</em>.
          Instead of real regular expression strings you can also
          use one of the following: 

          <ul>
            <li>'<strong>&lt;CondPattern</strong>' (is lexically
            lower)<br />
             Treats the <em>CondPattern</em> as a plain string and
            compares it lexically to <em>TestString</em>. True if
            <em>TestString</em> is lexically lower than
            <em>CondPattern</em>.</li>

            <li>'<strong>&gt;CondPattern</strong>' (is lexically
            greater)<br />
             Treats the <em>CondPattern</em> as a plain string and
            compares it lexically to <em>TestString</em>. True if
            <em>TestString</em> is lexically greater than
            <em>CondPattern</em>.</li>

            <li>'<strong>=CondPattern</strong>' (is lexically
            equal)<br />
             Treats the <em>CondPattern</em> as a plain string and
            compares it lexically to <em>TestString</em>. True if
            <em>TestString</em> is lexically equal to
            <em>CondPattern</em>, i.e the two strings are exactly
            equal (character by character). If <em>CondPattern</em>
            is just <code>""</code> (two quotation marks) this
            compares <em>TestString</em> to the empty string.</li>

            <li>'<strong>-d</strong>' (is
            <strong>d</strong>irectory)<br />
             Treats the <em>TestString</em> as a pathname and tests
            if it exists and is a directory.</li>

            <li>'<strong>-f</strong>' (is regular
            <strong>f</strong>ile)<br />
             Treats the <em>TestString</em> as a pathname and tests
            if it exists and is a regular file.</li>

            <li>'<strong>-s</strong>' (is regular file with
            <strong>s</strong>ize)<br />
             Treats the <em>TestString</em> as a pathname and tests
            if it exists and is a regular file with size greater
            than zero.</li>

            <li>'<strong>-l</strong>' (is symbolic
            <strong>l</strong>ink)<br />
             Treats the <em>TestString</em> as a pathname and tests
            if it exists and is a symbolic link.</li>

            <li>'<strong>-F</strong>' (is existing file via
            subrequest)<br />
             Checks if <em>TestString</em> is a valid file and
            accessible via all the server's currently-configured
            access controls for that path. This uses an internal
            subrequest to determine the check, so use it with care
            because it decreases your servers performance!</li>

            <li>'<strong>-U</strong>' (is existing URL via
            subrequest)<br />
             Checks if <em>TestString</em> is a valid URL and
            accessible via all the server's currently-configured
            access controls for that path. This uses an internal
            subrequest to determine the check, so use it with care
            because it decreases your server's performance!</li>
          </ul>

<div class="note"><h3>Notice</h3>
              All of these tests can
              also be prefixed by an exclamation mark ('!') to
              negate their meaning.
</div>
        </li>
      </ol>

      <p>Additionally you can set special flags for
      <em>CondPattern</em> by appending</p>

      <p class="indent">
        <strong><code>[</code><em>flags</em><code>]</code></strong>
      </p>

      <p>as the third argument to the <code>RewriteCond</code>
      directive. <em>Flags</em> is a comma-separated list of the
      following flags:</p>

      <ul>
        <li>'<strong><code>nocase|NC</code></strong>'
        (<strong>n</strong>o <strong>c</strong>ase)<br />
         This makes the test case-insensitive, <em>i.e.</em>, there
        is no difference between 'A-Z' and 'a-z' both in the
        expanded <em>TestString</em> and the <em>CondPattern</em>.
        This flag is effective only for comparisons between
        <em>TestString</em> and <em>CondPattern</em>. It has no
        effect on filesystem and subrequest checks.</li>

        <li>
          '<strong><code>ornext|OR</code></strong>'
          (<strong>or</strong> next condition)<br />
           Use this to combine rule conditions with a local OR
          instead of the implicit AND. Typical example: 

<div class="example"><pre>
RewriteCond %{REMOTE_HOST}  ^host1.*  [OR]
RewriteCond %{REMOTE_HOST}  ^host2.*  [OR]
RewriteCond %{REMOTE_HOST}  ^host3.*
RewriteRule ...some special stuff for any of these hosts...
</pre></div>

          Without this flag you would have to write the cond/rule
          three times.
        </li>
      </ul>

      <p><strong>Example:</strong></p>

       <p>To rewrite the Homepage of a site according to the
        ``<code>User-Agent:</code>'' header of the request, you can
        use the following: </p>

<div class="example"><pre>
RewriteCond  %{HTTP_USER_AGENT}  ^Mozilla.*
RewriteRule  ^/$                 /homepage.max.html  [L]

RewriteCond  %{HTTP_USER_AGENT}  ^Lynx.*
RewriteRule  ^/$                 /homepage.min.html  [L]

RewriteRule  ^/$                 /homepage.std.html  [L]
</pre></div>

        <p>Interpretation: If you use Netscape Navigator as your
        browser (which identifies itself as 'Mozilla'), then you
        get the max homepage, which includes Frames, <em>etc.</em>
        If you use the Lynx browser (which is Terminal-based), then
        you get the min homepage, which contains no images, no
        tables, <em>etc.</em> If you use any other browser you get
        the standard homepage.</p>


</div>
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<div class="directive-section"><h2><a name="RewriteEngine" id="RewriteEngine">RewriteEngine</a> <a name="rewriteengine" id="rewriteengine">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enables or disables runtime rewriting engine</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>RewriteEngine on|off</code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>RewriteEngine off</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_rewrite</td></tr>
</table>       

      <p>The <code class="directive">RewriteEngine</code> directive enables or
      disables the runtime rewriting engine. If it is set to
      <code>off</code> this module does no runtime processing at
      all. It does not even update the <code>SCRIPT_URx</code>
      environment variables.</p>

      <p>Use this directive to disable the module instead of
      commenting out all the <code class="directive"><a href="#rewriterule">RewriteRule</a></code> directives!</p>

      <p>Note that, by default, rewrite configurations are not
      inherited. This means that you need to have a
      <code>RewriteEngine on</code> directive for each virtual host
      in which you wish to use it.</p>

</div>
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