xforms

<table class="directive">

<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Sets the base URL for per-directory rewrites</td></tr>

<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>RewriteBase <em>URL-path</em></code></td></tr>

<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>See usage for information.</code></td></tr>

<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>None</code></td></tr>

<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>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">RewriteBase</code> directive explicitly

      sets the base URL for per-directory rewrites. As you will see

      below, <code class="directive"><a href="#rewriterule">RewriteRule</a></code>

      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; <code class="directive">RewriteBase</code> <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>

<div class="note"> If your webserver's URLs are <strong>not</strong> directly

related to physical file paths, you will need to use

<code class="directive">RewriteBase</code> in every <code>.htaccess</code>

file where you want to use <code class="directive"><a href="#rewriterule">RewriteRule</a></code> directives.

</div>

        <p> For example, assume the following per-directory config file:</p>

      <p>The <code class="directive">RewriteBase</code> directive specifies the

      URL prefix to be used for per-directory (htaccess) 

      <code class="directive">RewriteRule</code> 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 

               <code class="directive"><a href="../mod/core.html#documentroot">DocumentRoot</a></code>

               (as opposed to reachable by other means, such as 

               <code class="directive"><a href="../mod/mod_alias.html#alias">Alias</a></code>).</li>

          <li> The <em>filesystem</em> path to the directory containing the

               <code class="directive">RewriteRule</code>, 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, <code class="directive">RewriteBase</code> is necessary

    to avoid rewriting to http://example.com/opt/myapp-1.2.3/welcome.html

    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>

<div class="example"><pre>

#

#  /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/example.com

Alias /myapp /opt/myapp-1.2.3

<Directory /opt/myapp-1.2.3>

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 

</Directory>

</pre></div>

        <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>

<div class="note"><h3>For Apache Hackers</h3>

<p>The following list gives detailed information about

              the internal processing steps:</p>

<pre>

Request:

  /xyz/oldstuff.html

Internal Processing:

  /xyz/oldstuff.html     -> /abc/def/oldstuff.html  (per-server Alias)

  /abc/def/oldstuff.html -> /abc/def/newstuff.html  (per-dir    RewriteRule)

  /abc/def/newstuff.html -> /xyz/newstuff.html      (per-dir    RewriteBase)

  /xyz/newstuff.html     -> /abc/def/newstuff.html  (per-server Alias)

Result:

  /abc/def/newstuff.html

</pre>

              <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> 

</div>

</div>

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

<div class="directive-section"><h2><a name="RewriteCond" id="RewriteCond">RewriteCond</a> <a name="rewritecond" id="rewritecond">Directive</a></h2>

</div>

<div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#synopsis">Synopsis</a></li>

<li><img alt="" src="../images/down.gif" /> <a href="#options">Options</a></li>

<li><img alt="" src="../images/down.gif" /> <a href="#output">Description of output</a></li>

<li><img alt="" src="../images/down.gif" /> <a href="#bugs">Bugs</a></li>

<li><img alt="" src="../images/down.gif" /> <a href="#output">Example Output</a></li>

</ul><h3>See also</h3><ul class="seealso"><li><code class="program"><a href="../programs/httpd.html">httpd</a></code></li></ul></div>

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

<div class="section">

    </dl>

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

<div class="section">

<h2><a name="bugs" id="bugs">Bugs</a></h2>

    <p>There are various statically declared buffers of fixed length. Combined

    with the lazy parsing of the command line arguments, the response headers

    from the server and other external inputs, this might bite you.</p>

    <p>It does not implement HTTP/1.x fully; only accepts some 'expected' forms

    of responses. The rather heavy use of <code>strstr(3)</code> shows up top

    in profile, which might indicate a performance problem; <em>i.e.</em>, you

    would measure the <code>ab</code> performance rather than the server's.</p>

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

<div class="section">

<h2><a name="output" id="output">Example Output</a></h2>

    <p>Sample output is provided here.</p>

    <div class="note"><pre>Server Software:        Apache/2.2.17

Server Hostname:        testserver.com

Server Port:            80

Document Path:          /index.html

Document Length:        787 bytes

Concurrency Level:      5

Time taken for tests:   0.436 seconds

Complete requests:      1000

Failed requests:        0

Write errors:           0

Total transferred:      1026000 bytes

HTML transferred:       787000 bytes

Requests per second:    2292.26 [#/sec] (mean)

Time per request:       2.181 [ms] (mean)

Time per request:       0.436 [ms] (mean, across all concurrent requests)

Transfer rate:          2296.74 [Kbytes/sec] received

Connection Times (ms)

              min  mean[+/-sd] median   max

Connect:        0    1   0.4      1       3

Processing:     1    1   0.4      1       3

Waiting:        0    1   0.5      1       2

Total:          2    2   0.1      2       3

Percentage of the requests served within a certain time (ms)

  50%      2

  66%      2

  75%      2

  80%      2

  90%      2

  95%      2

  98%      2

  99%      3

 100%      3 (longest request)</pre></div>

<h2><a name="output" id="output">Description of output</a></h2>

    <p>The output may vary depending on the command line parameters given.

    Possible output with a brief explanation of each element is listed below.

    </p>

        <dd>The rate of transfer as calculated by the formula

        <code>totalread / 1024 / timetaken</code></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="bugs" id="bugs">Bugs</a></h2>

    <p>There are various statically declared buffers of fixed length. Combined

    with the lazy parsing of the command line arguments, the response headers

    from the server and other external inputs, this might bite you.</p>

    <p>It does not implement HTTP/1.x fully; only accepts some 'expected' forms

    of responses. The rather heavy use of <code>strstr(3)</code> shows up top

    in profile, which might indicate a performance problem; <em>i.e.</em>, you

    would measure the <code>ab</code> performance rather than the server's.</p>

</div></div>

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