rewriteguide.html.en

apache的软件linux版本

          character of the username. So, <code>/~foo/anypath</code>
          is <code>/home/<strong>f</strong>/foo/.www/anypath</code>
          while <code>/~bar/anypath</code> is
          <code>/home/<strong>b</strong>/bar/.www/anypath</code>.</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>We use the following ruleset to expand the tilde URLs
          into exactly the above layout.</p>

<div class="example"><pre>
RewriteEngine on
RewriteRule   ^/~(<strong>([a-z])</strong>[a-z0-9]+)(.*)  /home/<strong>$2</strong>/$1/.www$3
</pre></div>
        </dd>
      </dl>

    

    <h3>Filesystem Reorganization</h3>

      

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

        <dd>
          <p>This really is a hardcore example: a killer application
          which heavily uses per-directory
          <code>RewriteRules</code> to get a smooth look and feel
          on the Web while its data structure is never touched or
          adjusted. Background: <strong><em>net.sw</em></strong> is
          my archive of freely available Unix software packages,
          which I started to collect in 1992. It is both my hobby
          and job to to this, because while I'm studying computer
          science I have also worked for many years as a system and
          network administrator in my spare time. Every week I need
          some sort of software so I created a deep hierarchy of
          directories where I stored the packages:</p>

<div class="example"><pre>
drwxrwxr-x   2 netsw  users    512 Aug  3 18:39 Audio/
drwxrwxr-x   2 netsw  users    512 Jul  9 14:37 Benchmark/
drwxrwxr-x  12 netsw  users    512 Jul  9 00:34 Crypto/
drwxrwxr-x   5 netsw  users    512 Jul  9 00:41 Database/
drwxrwxr-x   4 netsw  users    512 Jul 30 19:25 Dicts/
drwxrwxr-x  10 netsw  users    512 Jul  9 01:54 Graphic/
drwxrwxr-x   5 netsw  users    512 Jul  9 01:58 Hackers/
drwxrwxr-x   8 netsw  users    512 Jul  9 03:19 InfoSys/
drwxrwxr-x   3 netsw  users    512 Jul  9 03:21 Math/
drwxrwxr-x   3 netsw  users    512 Jul  9 03:24 Misc/
drwxrwxr-x   9 netsw  users    512 Aug  1 16:33 Network/
drwxrwxr-x   2 netsw  users    512 Jul  9 05:53 Office/
drwxrwxr-x   7 netsw  users    512 Jul  9 09:24 SoftEng/
drwxrwxr-x   7 netsw  users    512 Jul  9 12:17 System/
drwxrwxr-x  12 netsw  users    512 Aug  3 20:15 Typesetting/
drwxrwxr-x  10 netsw  users    512 Jul  9 14:08 X11/
</pre></div>

          <p>In July 1996 I decided to make this archive public to
          the world via a nice Web interface. "Nice" means that I
          wanted to offer an interface where you can browse
          directly through the archive hierarchy. And "nice" means
          that I didn't wanted to change anything inside this
          hierarchy - not even by putting some CGI scripts at the
          top of it. Why? Because the above structure should be
          later accessible via FTP as well, and I didn't want any
          Web or CGI stuff to be there.</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>The solution has two parts: The first is a set of CGI
          scripts which create all the pages at all directory
          levels on-the-fly. I put them under
          <code>/e/netsw/.www/</code> as follows:</p>

<div class="example"><pre>
-rw-r--r--   1 netsw  users    1318 Aug  1 18:10 .wwwacl
drwxr-xr-x  18 netsw  users     512 Aug  5 15:51 DATA/
-rw-rw-rw-   1 netsw  users  372982 Aug  5 16:35 LOGFILE
-rw-r--r--   1 netsw  users     659 Aug  4 09:27 TODO
-rw-r--r--   1 netsw  users    5697 Aug  1 18:01 netsw-about.html
-rwxr-xr-x   1 netsw  users     579 Aug  2 10:33 netsw-access.pl
-rwxr-xr-x   1 netsw  users    1532 Aug  1 17:35 netsw-changes.cgi
-rwxr-xr-x   1 netsw  users    2866 Aug  5 14:49 netsw-home.cgi
drwxr-xr-x   2 netsw  users     512 Jul  8 23:47 netsw-img/
-rwxr-xr-x   1 netsw  users   24050 Aug  5 15:49 netsw-lsdir.cgi
-rwxr-xr-x   1 netsw  users    1589 Aug  3 18:43 netsw-search.cgi
-rwxr-xr-x   1 netsw  users    1885 Aug  1 17:41 netsw-tree.cgi
-rw-r--r--   1 netsw  users     234 Jul 30 16:35 netsw-unlimit.lst
</pre></div>

          <p>The <code>DATA/</code> subdirectory holds the above
          directory structure, i.e. the real
          <strong><em>net.sw</em></strong> stuff and gets
          automatically updated via <code>rdist</code> from time to
          time. The second part of the problem remains: how to link
          these two structures together into one smooth-looking URL
          tree? We want to hide the <code>DATA/</code> directory
          from the user while running the appropriate CGI scripts
          for the various URLs. Here is the solution: first I put
          the following into the per-directory configuration file
          in the <code class="directive"><a href="../mod/core.html#documentroot">DocumentRoot</a></code>
          of the server to rewrite the announced URL
          <code>/net.sw/</code> to the internal path
          <code>/e/netsw</code>:</p>

<div class="example"><pre>
RewriteRule  ^net.sw$       net.sw/        [R]
RewriteRule  ^net.sw/(.*)$  e/netsw/$1
</pre></div>

          <p>The first rule is for requests which miss the trailing
          slash! The second rule does the real thing. And then
          comes the killer configuration which stays in the
          per-directory config file
          <code>/e/netsw/.www/.wwwacl</code>:</p>

<div class="example"><pre>
Options       ExecCGI FollowSymLinks Includes MultiViews

RewriteEngine on

#  we are reached via /net.sw/ prefix
RewriteBase   /net.sw/

#  first we rewrite the root dir to
#  the handling cgi script
RewriteRule   ^$                       netsw-home.cgi     [L]
RewriteRule   ^index\.html$            netsw-home.cgi     [L]

#  strip out the subdirs when
#  the browser requests us from perdir pages
RewriteRule   ^.+/(netsw-[^/]+/.+)$    $1                 [L]

#  and now break the rewriting for local files
RewriteRule   ^netsw-home\.cgi.*       -                  [L]
RewriteRule   ^netsw-changes\.cgi.*    -                  [L]
RewriteRule   ^netsw-search\.cgi.*     -                  [L]
RewriteRule   ^netsw-tree\.cgi$        -                  [L]
RewriteRule   ^netsw-about\.html$      -                  [L]
RewriteRule   ^netsw-img/.*$           -                  [L]

#  anything else is a subdir which gets handled
#  by another cgi script
RewriteRule   !^netsw-lsdir\.cgi.*     -                  [C]
RewriteRule   (.*)                     netsw-lsdir.cgi/$1
</pre></div>

          <p>Some hints for interpretation:</p>

          <ol>
            <li>Notice the <code>L</code> (last) flag and no
            substitution field ('<code>-</code>') in the forth part</li>

            <li>Notice the <code>!</code> (not) character and
            the <code>C</code> (chain) flag at the first rule
            in the last part</li>

            <li>Notice the catch-all pattern in the last rule</li>
          </ol>
        </dd>
      </dl>

    

    <h3>NCSA imagemap to Apache <code>mod_imap</code></h3>

      

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

        <dd>
          <p>When switching from the NCSA webserver to the more
          modern Apache webserver a lot of people want a smooth
          transition. So they want pages which use their old NCSA
          <code>imagemap</code> program to work under Apache with the
          modern <code class="module"><a href="../mod/mod_imap.html">mod_imap</a></code>. The problem is that there
          are a lot of hyperlinks around which reference the
          <code>imagemap</code> program via
          <code>/cgi-bin/imagemap/path/to/page.map</code>. Under
          Apache this has to read just
          <code>/path/to/page.map</code>.</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>We use a global rule to remove the prefix on-the-fly for
          all requests:</p>

<div class="example"><pre>
RewriteEngine  on
RewriteRule    ^/cgi-bin/imagemap(.*)  $1  [PT]
</pre></div>
        </dd>
      </dl>

    

    <h3>Search pages in more than one directory</h3>

      

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

        <dd>
          <p>Sometimes it is necessary to let the webserver search
          for pages in more than one directory. Here MultiViews or
          other techniques cannot help.</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>We program a explicit ruleset which searches for the
          files in the directories.</p>

<div class="example"><pre>
RewriteEngine on

#   first try to find it in custom/...
#   ...and if found stop and be happy:
RewriteCond         /your/docroot/<strong>dir1</strong>/%{REQUEST_FILENAME}  -f
RewriteRule  ^(.+)  /your/docroot/<strong>dir1</strong>/$1  [L]

#   second try to find it in pub/...
#   ...and if found stop and be happy:
RewriteCond         /your/docroot/<strong>dir2</strong>/%{REQUEST_FILENAME}  -f
RewriteRule  ^(.+)  /your/docroot/<strong>dir2</strong>/$1  [L]

#   else go on for other Alias or ScriptAlias directives,
#   etc.
RewriteRule   ^(.+)  -  [PT]
</pre></div>
        </dd>
      </dl>

    

    <h3>Set Environment Variables According To URL Parts</h3>

      

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

        <dd>
          <p>Perhaps you want to keep status information between
          requests and use the URL to encode it. But you don't want
          to use a CGI wrapper for all pages just to strip out this
          information.</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>We use a rewrite rule to strip out the status information
          and remember it via an environment variable which can be
          later dereferenced from within XSSI or CGI. This way a
          URL <code>/foo/S=java/bar/</code> gets translated to
          <code>/foo/bar/</code> and the environment variable named
          <code>STATUS</code> is set to the value "java".</p>

<div class="example"><pre>
RewriteEngine on
RewriteRule   ^(.*)/<strong>S=([^/]+)</strong>/(.*)    $1/$3 [E=<strong>STATUS:$2</strong>]
</pre></div>
        </dd>
      </dl>

    

    <h3>Virtual User Hosts</h3>

      

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

        <dd>
          <p>Assume that you want to provide
          <code>www.<strong>username</strong>.host.domain.com</code>
          for the homepage of username via just DNS A records to the
          same machine and without any virtualhosts on this
          machine.</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>For HTTP/1.0 requests there is no solution, but for
          HTTP/1.1 requests which contain a Host: HTTP header we
          can use the following ruleset to rewrite
          <code>http://www.username.host.com/anypath</code>
          internally to <code>/home/username/anypath</code>:</p>

<div class="example"><pre>
RewriteEngine on
RewriteCond   %{<strong>HTTP_HOST</strong>}                 ^www\.<strong>[^.]+</strong>\.host\.com$
RewriteRule   ^(.+)                        %{HTTP_HOST}$1          [C]
RewriteRule   ^www\.<strong>([^.]+)</strong>\.host\.com(.*) /home/<strong>$1</strong>$2
</pre></div>
        </dd>
      </dl>

    

    <h3>Redirect Homedirs For Foreigners</h3>

      

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

        <dd>
          <p>We want to redirect homedir URLs to another webserver
          <code>www.somewhere.com</code> when the requesting user
          does not stay in the local domain
          <code>ourdomain.com</code>. This is sometimes used in
          virtual host contexts.</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>Just a rewrite condition:</p>

<div class="example"><pre>
RewriteEngine on
RewriteCond   %{REMOTE_HOST}  <strong>!^.+\.ourdomain\.com$</strong>
RewriteRule   ^(/~.+)         http://www.somewhere.com/$1 [R,L]
</pre></div>
        </dd>
      </dl>

    

    <h3>Redirect Failing URLs To Other Webserver</h3>

      

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

        <dd>
          <p>A typical FAQ about URL rewriting is how to redirect
          failing requests on webserver A to webserver B. Usually
          this is done via <code class="directive"><a href="../mod/core.html#errordocument">ErrorDocument</a></code> CGI-scripts in Perl, but
          there is also a <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> solution.
          But notice that this performs more poorly than using an
          <code class="directive"><a href="../mod/core.html#errordocument">ErrorDocument</a></code>
          CGI-script!</p>
        </dd>

        <dt>Solution:</dt>

        <dd>
          <p>The first solution has the best performance but less
          flexibility, and is less error safe:</p>

<div class="example"><pre>
RewriteEngine on
RewriteCond   /your/docroot/%{REQUEST_FILENAME} <strong>!-f</strong>
RewriteRule   ^(.+)                             http://<strong>webserverB</strong>.dom/$1
</pre></div>

          <p>The problem here is that this will only work for pages
          inside the <code class="directive"><a href="../mod/core.html#documentroot">DocumentRoot</a></code>. While you can add more
          Conditions (for instance to also handle homedirs, etc.)
          there is better variant:</p>

<div class="example"><pre>
RewriteEngine on
RewriteCond   %{REQUEST_URI} <strong>!-U</strong>
RewriteRule   ^(.+)          http://<strong>webserverB</strong>.dom/$1
</pre></div>