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-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
- "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<!--%hypertext -->
-<!-- mod_rewrite.html -->
-<!-- Documentation for the mod_rewrite Apache module -->
-
-<html xmlns="http://www.w3.org/1999/xhtml">
- <head>
- <meta name="generator" content="HTML Tidy, see www.w3.org" />
-
- <title>Apache module mod_rewrite</title>
- </head>
- <!-- Background white, links blue (unvisited), navy (visited), red (active) -->
-
- <body bgcolor="#FFFFFF" text="#000000" link="#0000FF"
- vlink="#000080" alink="#FF0000">
- <blockquote>
- <!-- page indentation -->
- <div align="CENTER">
- <img src="../images/sub.gif" alt="[APACHE DOCUMENTATION]" />
-
- <h3>Apache HTTP Server Version 1.3</h3>
- </div>
-
- <br />
-
-
- <h1 align="CENTER">Module mod_rewrite<br />
- URL Rewriting Engine</h1>
-
- <p>This module provides a rule-based rewriting engine to
- rewrite requested URLs on the fly.</p>
-
- <p><a href="module-dict.html#Status"
- rel="Help"><strong>Status:</strong></a> Extension<br />
- <a href="module-dict.html#SourceFile"
- rel="Help"><strong>Source File:</strong></a>
- mod_rewrite.c<br />
- <a href="module-dict.html#ModuleIdentifier"
- rel="Help"><strong>Module Identifier:</strong></a>
- rewrite_module<br />
- <a href="module-dict.html#Compatibility"
- rel="Help"><strong>Compatibility:</strong></a> Available in
- Apache 1.2 and later.</p>
- <hr noshade="noshade" size="1" />
- <br />
-
-
- <h2>Summary</h2>
-
- <blockquote>
- <blockquote>
- <blockquote>
- <em>``The great thing about mod_rewrite is it gives you
- all the configurability and flexibility of Sendmail.
- The downside to mod_rewrite is that it gives you all
- the configurability and flexibility of Sendmail.''</em>
-
-
- <div align="RIGHT">
- -- Brian Behlendorf<br />
- Apache Group
- </div>
- </blockquote>
- </blockquote>
- </blockquote>
-
- <blockquote>
- <blockquote>
- <blockquote>
- <em>`` Despite the tons of examples and docs,
- mod_rewrite is voodoo. Damned cool voodoo, but still
- voodoo. ''</em>
-
- <div align="RIGHT">
- -- Brian Moore<br />
- bem@news.cmc.net
- </div>
- </blockquote>
- </blockquote>
- </blockquote>
- Welcome to mod_rewrite, the Swiss Army Knife of URL
- manipulation!
-
- <p>This module uses a rule-based rewriting engine (based on a
- regular-expression parser) to rewrite requested URLs on the
- fly. It supports an unlimited number of rules and an
- unlimited number of attached rule conditions for each rule to
- provide a really flexible and powerful URL manipulation
- mechanism. The URL manipulations can depend on various tests,
- for instance server variables, environment variables, HTTP
- headers, time stamps and even external database lookups in
- various formats can be used to achieve a really granular URL
- matching.</p>
-
- <p>This module operates on the full URLs (including the
- path-info part) both in per-server context
- (<code>httpd.conf</code>) and per-directory context
- (<code>.htaccess</code>) and can even generate query-string
- parts on result. The rewritten result can lead to internal
- sub-processing, external request redirection or even to an
- internal proxy throughput.</p>
-
- <p>But all this functionality and flexibility has its
- drawback: complexity. So don't expect to understand this
- entire module in just one day.</p>
-
- <p>This module was invented and originally written in April
- 1996<br />
- and gifted exclusively to the The Apache Group in July 1997
- by</p>
-
- <blockquote>
- <a href="http://www.engelschall.com/"><code>Ralf S.
- Engelschall</code></a><br />
- <a
- href="mailto:rse@engelschall.com"><code>rse@engelschall.com</code></a><br />
- <a
- href="http://www.engelschall.com/"><code>www.engelschall.com</code></a>
- </blockquote>
- <hr noshade="noshade" size="1" />
-
- <h2>Table Of Contents</h2>
-
- <p><strong>Internal Processing</strong></p>
-
- <ul>
- <li><a href="#InternalAPI">API Phases</a></li>
-
- <li><a href="#InternalRuleset">Ruleset Processing</a></li>
-
- <li><a href="#InternalBackRefs">Regex Back-Reference
- Availability</a></li>
- </ul>
-
- <p><strong>Configuration Directives</strong></p>
-
- <ul>
- <li><a href="#RewriteEngine">RewriteEngine</a></li>
-
- <li><a href="#RewriteOptions">RewriteOptions</a></li>
-
- <li><a href="#RewriteLog">RewriteLog</a></li>
-
- <li><a href="#RewriteLogLevel">RewriteLogLevel</a></li>
-
- <li><a href="#RewriteLock">RewriteLock</a></li>
-
- <li><a href="#RewriteMap">RewriteMap</a></li>
-
- <li><a href="#RewriteBase">RewriteBase</a></li>
-
- <li><a href="#RewriteCond">RewriteCond</a></li>
-
- <li><a href="#RewriteRule">RewriteRule</a></li>
- </ul>
- <strong>Miscellaneous</strong>
-
- <ul>
- <li><a href="#EnvVar">Environment Variables</a></li>
-
- <li><a href="#Solutions">Practical Solutions</a></li>
- </ul>
- <hr noshade="noshade" size="1" />
-
- <center>
- <h1><a id="Internal" name="Internal">Internal
- Processing</a></h1>
- </center>
- <hr noshade="noshade" size="1" />
-
- <p>The internal processing of this module is very complex but
- needs to be explained once even to the average user to avoid
- common mistakes and to let you exploit its full
- functionality.</p>
-
- <h2><a id="InternalAPI" name="InternalAPI">API
- Phases</a></h2>
-
- <p>First you have to understand that when Apache processes a
- HTTP request it does this in phases. A hook for each of these
- phases is provided by the Apache API. Mod_rewrite uses two of
- these hooks: the URL-to-filename translation hook which is
- used after the HTTP request has been read but before any
- authorization starts and the Fixup hook which is triggered
- after the authorization phases and after the per-directory
- config files (<code>.htaccess</code>) have been read, but
- before the content handler is activated.</p>
-
- <p>So, after a request comes in and Apache has determined the
- corresponding server (or virtual server) the rewriting engine
- starts processing of all mod_rewrite directives from the
- per-server configuration in the URL-to-filename phase. A few
- steps later when the final data directories are found, the
- per-directory configuration directives of mod_rewrite are
- triggered in the Fixup phase. In both situations mod_rewrite
- rewrites URLs either to new URLs or to filenames, although
- there is no obvious distinction between them. This is a usage
- of the API which was not intended to be this way when the API
- was designed, but as of Apache 1.x this is the only way
- mod_rewrite can operate. To make this point more clear
- remember the following two points:</p>
-
- <ol>
- <li>Although mod_rewrite rewrites URLs to URLs, URLs to
- filenames and even filenames to filenames, the API
- currently provides only a URL-to-filename hook. In Apache
- 2.0 the two missing hooks will be added to make the
- processing more clear. But this point has no drawbacks for
- the user, it is just a fact which should be remembered:
- Apache does more in the URL-to-filename hook than the API
- intends for it.</li>
-
- <li>
- Unbelievably mod_rewrite provides URL manipulations in
- per-directory context, <em>i.e.</em>, within
- <code>.htaccess</code> files, although these are reached
- a very long time after the URLs have been translated to
- filenames. It has to be this way because
- <code>.htaccess</code> files live in the filesystem, so
- processing has already reached this stage. In other
- words: According to the API phases at this time it is too
- late for any URL manipulations. To overcome this chicken
- and egg problem mod_rewrite uses a trick: When you
- manipulate a URL/filename in per-directory context
- mod_rewrite first rewrites the filename back to its
- corresponding URL (which is usually impossible, but see
- the <code>RewriteBase</code> directive below for the
- trick to achieve this) and then initiates a new internal
- sub-request with the new URL. This restarts processing of
- the API phases.
-
- <p>Again mod_rewrite tries hard to make this complicated
- step totally transparent to the user, but you should
- remember here: While URL manipulations in per-server
- context are really fast and efficient, per-directory
- rewrites are slow and inefficient due to this chicken and
- egg problem. But on the other hand this is the only way
- mod_rewrite can provide (locally restricted) URL
- manipulations to the average user.</p>
- </li>
- </ol>
-
- <p>Don't forget these two points!</p>
-
- <h2><a id="InternalRuleset" name="InternalRuleset">Ruleset
- Processing</a></h2>
- Now when mod_rewrite is triggered in these two API phases, it
- reads the configured rulesets from its configuration
- structure (which itself was either created on startup for
- per-server context or during the directory walk of the Apache
- kernel for per-directory context). Then the URL rewriting
- engine is started with the contained ruleset (one or more
- rules together with their conditions). The operation of the
- URL rewriting engine itself is exactly the same for both
- configuration contexts. Only the final result processing is
- different.
-
- <p>The order of rules in the ruleset is important because the
- rewriting engine processes them in a special (and not very
- obvious) order. The rule is this: The rewriting engine loops
- through the ruleset rule by rule (<code>RewriteRule</code>
- directives) and when a particular rule matches it optionally
- loops through existing corresponding conditions
- (<code>RewriteCond</code> directives). For historical reasons
- the conditions are given first, and so the control flow is a
- little bit long-winded. See Figure 1 for more details.</p>
-
- <div align="CENTER">
- <table cellspacing="0" cellpadding="2" border="0">
- <tr>
- <td bgcolor="#CCCCCC"><img
- src="../images/mod_rewrite_fig1.gif" width="428"
- height="385"
- alt="[Needs graphics capability to display]" /></td>
- </tr>
-
- <tr>
- <td align="CENTER"><strong>Figure 1:</strong> The
- control flow through the rewriting ruleset</td>
- </tr>
- </table>
- </div>
-
- <p>As you can see, first the URL is matched against the
- <em>Pattern</em> of each rule. When it fails mod_rewrite
- immediately stops processing this rule and continues with the
- next rule. If the <em>Pattern</em> matches, mod_rewrite looks
- for corresponding rule conditions. If none are present, it
- just substitutes the URL with a new value which is
- constructed from the string <em>Substitution</em> and goes on
- with its rule-looping. But if conditions exist, it starts an
- inner loop for processing them in the order that they are
- listed. For conditions the logic is different: we don't match
- a pattern against the current URL. Instead we first create a
- string <em>TestString</em> by expanding variables,
- back-references, map lookups, <em>etc.</em> and then we try
- to match <em>CondPattern</em> against it. If the pattern
- doesn't match, the complete set of conditions and the
- corresponding rule fails. If the pattern matches, then the
- next condition is processed until no more conditions are
- available. If all conditions match, processing is continued
- with the substitution of the URL with
- <em>Substitution</em>.</p>
-
- <h2><a id="quoting" name="quoting">Quoting Special
- Characters</a></h2>
-
- <p>As of Apache 1.3.20, special characters in
- <i>TestString</i> and <i>Substitution</i> strings can be
- escaped (that is, treated as normal characters without their
- usual special meaning) by prefixing them with a slosh ('\')
- character. In other words, you can include an actual
- dollar-sign character in a <i>Substitution</i> string by
- using '<code>\$</code>'; this keeps mod_rewrite from trying
- to treat it as a backreference.</p>
-
- <h2><a id="InternalBackRefs" name="InternalBackRefs">Regex
- Back-Reference Availability</a></h2>
- One important thing here has to be remembered: Whenever you
- use parentheses in <em>Pattern</em> or in one of the
- <em>CondPattern</em>, back-references are internally created
- which can be used with the strings <code>$N</code> and
- <code>%N</code> (see below). These are available for creating
- the strings <em>Substitution</em> and <em>TestString</em>.
- Figure 2 shows to which locations the back-references are
- transfered for expansion.
-
- <div align="CENTER">
- <table cellspacing="0" cellpadding="2" border="0">
- <tr>
- <td bgcolor="#CCCCCC"><img
- src="../images/mod_rewrite_fig2.gif" width="381"
- height="179"
- alt="[Needs graphics capability to display]" /></td>
- </tr>
-
- <tr>
- <td align="CENTER"><strong>Figure 2:</strong> The
- back-reference flow through a rule</td>
- </tr>
- </table>
- </div>
-
- <p>We know this was a crash course on mod_rewrite's internal
- processing. But you will benefit from this knowledge when
- reading the following documentation of the available
- directives.</p>
- <hr noshade="noshade" size="1" />
-
- <center>
- <h1><a id="Configuration"
- name="Configuration">Configuration Directives</a></h1>
- </center>
- <hr noshade="noshade" size="1" />
-
- <h3><a id="RewriteEngine"
- name="RewriteEngine">RewriteEngine</a></h3>
- <a href="directive-dict.html#Syntax"
- rel="Help"><strong>Syntax:</strong></a> RewriteEngine
- on|off<br />
- <a href="directive-dict.html#Default"
- rel="Help"><strong>Default:</strong></a> <code>RewriteEngine
- off</code><br />
- <a href="directive-dict.html#Context"
- rel="Help"><strong>Context:</strong></a> server config,
- virtual host, directory, .htaccess<br />
- <a href="directive-dict.html#Override"
- rel="Help"><strong>Override:</strong></a> FileInfo<br />
- <a href="directive-dict.html#Status"
- rel="Help"><strong>Status:</strong></a> Extension<br />
- <a href="directive-dict.html#Module"
- rel="Help"><strong>Module:</strong></a> mod_rewrite.c<br />
- <a href="directive-dict.html#Compatibility"
- rel="Help"><strong>Compatibility:</strong></a> Apache
- 1.2<br />
-
-
- <p>The <code>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>RewriteRule</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>
- <hr noshade="noshade" size="1" />
-
- <h3><a id="RewriteOptions"
- name="RewriteOptions">RewriteOptions</a></h3>
- <a href="directive-dict.html#Syntax"
- rel="Help"><strong>Syntax:</strong></a> RewriteOptions
- <em>Option</em><br />
- <a href="directive-dict.html#Default"
- rel="Help"><strong>Default:</strong></a> <code>RewriteOptions
- MaxRedirects=10</code><br />
- <a href="directive-dict.html#Context"
- rel="Help"><strong>Context:</strong></a> server config,
- virtual host, directory, .htaccess<br />
- <a href="directive-dict.html#Override"
- rel="Help"><strong>Override:</strong></a> FileInfo<br />
- <a href="directive-dict.html#Status"
- rel="Help"><strong>Status:</strong></a> Extension<br />
- <a href="directive-dict.html#Module"
- rel="Help"><strong>Module:</strong></a> mod_rewrite.c<br />
- <a href="directive-dict.html#Compatibility"
- rel="Help"><strong>Compatibility:</strong></a> Apache
- 1.2; <code>MaxRedirects</code> is available in Apache 1.3.28 and
- later<br />
-
-
- <p>The <code>RewriteOptions</code> directive sets some
- special options for the current per-server or per-directory
- configuration. The <em>Option</em> strings can be one of the
- following:</p>
-
- <dl>
- <dt><code>inherit</code></dt>
- <dd>This forces the current configuration to inherit the
- configuration of the parent. In per-virtual-server context
- this means that the maps, conditions and rules of the main
- server are inherited. In per-directory context this means
- that conditions and rules of the parent directory's
- <code>.htaccess</code> configuration are inherited.</dd>
-
- <dt><code>MaxRedirects=<var>number</var></code></dt>
- <dd>In order to prevent endless loops of internal redirects
- issued by per-directory <code>RewriteRule</code>s,
- <code>mod_rewrite</code> aborts the request after reaching a
- maximum number of such redirects and responds with an 500 Internal
- Server Error. If you really need more internal redirects than 10
- per request, you may increase the default to the desired value.</dd>
- </dl>
- <hr noshade="noshade" size="1" />
-
- <h3><a id="RewriteLog" name="RewriteLog">RewriteLog</a></h3>
- <a href="directive-dict.html#Syntax"
- rel="Help"><strong>Syntax:</strong></a> RewriteLog
- <em>file-path</em><br />
- <a href="directive-dict.html#Default"
- rel="Help"><strong>Default:</strong></a> <em>None</em><br />
- <a href="directive-dict.html#Context"
- rel="Help"><strong>Context:</strong></a> server config,
- virtual host<br />
- <a href="directive-dict.html#Override"
- rel="Help"><strong>Override:</strong></a> <em>Not
- applicable</em><br />
- <a href="directive-dict.html#Status"
- rel="Help"><strong>Status:</strong></a> Extension<br />
- <a href="directive-dict.html#Module"
- rel="Help"><strong>Module:</strong></a> mod_rewrite.c<br />
- <a href="directive-dict.html#Compatibility"
- rel="Help"><strong>Compatibility:</strong></a> Apache
- 1.2<br />
-
-
- <p>The <code>RewriteLog</code> directive sets the name of the
- file to which the server logs any rewriting actions it
- performs. If the name does not begin with a slash
- ('<code>/</code>') then it is assumed to be relative to the
- <em>Server Root</em>. The directive should occur only once
- per server config.</p>
-
- <table width="70%" border="0" bgcolor="#E0E0F0"
- cellspacing="0" cellpadding="10">
- <tr>
- <td><strong>Note</strong>: To disable the logging of
- rewriting actions it is not recommended to set
- <em>file-path</em> to <code>/dev/null</code>, because
- although the rewriting engine does not then output to a
- logfile it still creates the logfile output internally.
- <strong>This will slow down the server with no advantage
- to the administrator!</strong> To disable logging either
- remove or comment out the <code>RewriteLog</code>
- directive or use <code>RewriteLogLevel 0</code>!</td>
- </tr>
- </table>
-
- <table width="70%" border="0" bgcolor="#E0E0F0"
- cellspacing="0" cellpadding="10">
- <tr>
- <td><strong>Security</strong>: See the <a
- href="../misc/security_tips.html">Apache Security
- Tips</a> document for details on why your security could
- be compromised if the directory where logfiles are stored
- is writable by anyone other than the user that starts the
- server.</td>
- </tr>
- </table>
-
- <p><strong>Example:</strong></p>
-
- <blockquote>
-<pre>
-RewriteLog "/usr/local/var/apache/logs/rewrite.log"
-</pre>
- </blockquote>
- <hr noshade="noshade" size="1" />
-
- <h3><a id="RewriteLogLevel"
- name="RewriteLogLevel">RewriteLogLevel</a></h3>
- <a href="directive-dict.html#Syntax"
- rel="Help"><strong>Syntax:</strong></a> RewriteLogLevel
- <em>Level</em><br />
- <a href="directive-dict.html#Default"
- rel="Help"><strong>Default:</strong></a>
- <code>RewriteLogLevel 0</code><br />
- <a href="directive-dict.html#Context"
- rel="Help"><strong>Context:</strong></a> server config,
- virtual host<br />
- <a href="directive-dict.html#Override"
- rel="Help"><strong>Override:</strong></a> <em>Not
- applicable</em><br />
- <a href="directive-dict.html#Status"
- rel="Help"><strong>Status:</strong></a> Extension<br />
- <a href="directive-dict.html#Module"
- rel="Help"><strong>Module:</strong></a> mod_rewrite.c<br />
- <a href="directive-dict.html#Compatibility"
- rel="Help"><strong>Compatibility:</strong></a> Apache
- 1.2<br />
-
-
- <p>The <code>RewriteLogLevel</code> directive sets the
- verbosity level of the rewriting logfile. The default level 0
- means no logging, while 9 or more means that practically all
- actions are logged.</p>
-
- <p>To disable the logging of rewriting actions simply set
- <em>Level</em> to 0. This disables all rewrite action
- logs.</p>
-
- <table width="70%" border="0" bgcolor="#E0E0F0"
- cellspacing="0" cellpadding="10">
- <tr>
- <td><strong>Notice:</strong> Using a high value for
- <em>Level</em> will slow down your Apache server
- dramatically! Use the rewriting logfile at a
- <em>Level</em> greater than 2 only for debugging!</td>
- </tr>
- </table>
-
- <p><strong>Example:</strong></p>
-
- <blockquote>
-<pre>
-RewriteLogLevel 3
-</pre>
- </blockquote>
- <hr noshade="noshade" size="1" />
-
- <h3><a id="RewriteLock"
- name="RewriteLock">RewriteLock</a></h3>
- <a href="directive-dict.html#Syntax"
- rel="Help"><strong>Syntax:</strong></a> RewriteLock
- <em>file-path</em><br />
- <a href="directive-dict.html#Default"
- rel="Help"><strong>Default:</strong></a> <em>None</em><br />
- <a href="directive-dict.html#Context"
- rel="Help"><strong>Context:</strong></a> server config<br />
- <a href="directive-dict.html#Override"
- rel="Help"><strong>Override:</strong></a> <em>Not
- applicable</em><br />
- <a href="directive-dict.html#Status"
- rel="Help"><strong>Status:</strong></a> Extension<br />
- <a href="directive-dict.html#Module"
- rel="Help"><strong>Module:</strong></a> mod_rewrite.c<br />
- <a href="directive-dict.html#Compatibility"
- rel="Help"><strong>Compatibility:</strong></a> Apache
- 1.3<br />
-
-
- <p>This directive sets the filename for a synchronization
- lockfile which mod_rewrite needs to communicate with
- <samp>RewriteMap</samp> <em>programs</em>. Set this lockfile
- to a local path (not on a NFS-mounted device) when you want
- to use a rewriting map-program. It is not required for other
- types of rewriting maps.</p>
- <hr noshade="noshade" size="1" />
-
- <h3><a id="RewriteMap" name="RewriteMap">RewriteMap</a></h3>
- <a href="directive-dict.html#Syntax"
- rel="Help"><strong>Syntax:</strong></a> RewriteMap
- <em>MapName</em> <em>MapType</em>:<em>MapSource</em><br />
- <a href="directive-dict.html#Default"
- rel="Help"><strong>Default:</strong></a> not used per
- default<br />
- <a href="directive-dict.html#Context"
- rel="Help"><strong>Context:</strong></a> server config,
- virtual host<br />
- <a href="directive-dict.html#Override"
- rel="Help"><strong>Override:</strong></a> <em>Not
- applicable</em><br />
- <a href="directive-dict.html#Status"
- rel="Help"><strong>Status:</strong></a> Extension<br />
- <a href="directive-dict.html#Module"
- rel="Help"><strong>Module:</strong></a> mod_rewrite.c<br />
- <a href="directive-dict.html#Compatibility"
- rel="Help"><strong>Compatibility:</strong></a> Apache 1.2
- (partially), Apache 1.3<br />
-
-
- <p>The <code>RewriteMap</code> directive defines a
- <em>Rewriting Map</em> which can be used inside rule
- substitution strings by the mapping-functions to
- insert/substitute fields through a key lookup. The source of
- this lookup can be of various types.</p>
-
- <p>The <a id="mapfunc" name="mapfunc"><em>MapName</em></a> is
- the name of the map and will be used to specify a
- mapping-function for the substitution strings of a rewriting
- rule via one of the following constructs:</p>
-
- <blockquote>
- <strong><code>${</code> <em>MapName</em> <code>:</code>
- <em>LookupKey</em> <code>}</code><br />
- <code>${</code> <em>MapName</em> <code>:</code>
- <em>LookupKey</em> <code>|</code> <em>DefaultValue</em>
- <code>}</code></strong>
- </blockquote>
- When such a construct occurs the map <em>MapName</em> is
- consulted and the key <em>LookupKey</em> is looked-up. If the
- key is found, the map-function construct is substituted by
- <em>SubstValue</em>. If the key is not found then it is
- substituted by <em>DefaultValue</em> or by the empty string
- if no <em>DefaultValue</em> was specified.
-
- <p>The following combinations for <em>MapType</em> and
- <em>MapSource</em> can be used:</p>
-
- <ul>
- <li>
- <strong>Standard Plain Text</strong><br />
- MapType: <code>txt</code>, MapSource: Unix filesystem
- path to valid regular file
-
- <p>This is the standard rewriting map feature where the
- <em>MapSource</em> is a plain ASCII file containing
- either blank lines, comment lines (starting with a '#'
- character) or pairs like the following - one per
- line.</p>
-
- <blockquote>
- <strong><em>MatchingKey</em>
- <em>SubstValue</em></strong>
- </blockquote>
-
- <p>Example:</p>
-
- <table border="0" cellspacing="1" cellpadding="5"
- bgcolor="#F0F0F0">
- <tr>
- <td>
-<pre>
-##
-## map.txt -- rewriting map
-##
-
-Ralf.S.Engelschall rse # Bastard Operator From Hell
-Mr.Joe.Average joe # Mr. Average
-</pre>
- </td>
- </tr>
- </table>
-
- <table border="0" cellspacing="1" cellpadding="5"
- bgcolor="#F0F0F0">
- <tr>
- <td>
-<pre>
-RewriteMap real-to-user txt:/path/to/file/map.txt
-</pre>
- </td>
- </tr>
- </table>
- </li>
-
- <li>
- <strong>Randomized Plain Text</strong><br />
- MapType: <code>rnd</code>, MapSource: Unix filesystem
- path to valid regular file
-
- <p>This is identical to the Standard Plain Text variant
- above but with a special post-processing feature: After
- looking up a value it is parsed according to contained
- ``<code>|</code>'' characters which have the meaning of
- ``or''. In other words they indicate a set of
- alternatives from which the actual returned value is
- chosen randomly. Although this sounds crazy and useless,
- it was actually designed for load balancing in a reverse
- proxy situation where the looked up values are server
- names. Example:</p>
-
- <table border="0" cellspacing="1" cellpadding="5"
- bgcolor="#F0F0F0">
- <tr>
- <td>
-<pre>
-##
-## map.txt -- rewriting map
-##
-
-static www1|www2|www3|www4
-dynamic www5|www6
-</pre>
- </td>
- </tr>
- </table>
-
- <table border="0" cellspacing="1" cellpadding="5"
- bgcolor="#F0F0F0">
- <tr>
- <td>
-<pre>
-RewriteMap servers rnd:/path/to/file/map.txt
-</pre>
- </td>
- </tr>
- </table>
- </li>
-
- <li>
- <strong>Hash File</strong><br />
- MapType: <code>dbm</code>, MapSource: Unix filesystem
- path to valid regular file
-
- <p>Here the source is a binary NDBM format file
- containing the same contents as a <em>Plain Text</em>
- format file, but in a special representation which is
- optimized for really fast lookups. You can create such a
- file with any NDBM tool or with the following Perl
- script:</p>
-
- <table border="0" cellspacing="1" cellpadding="5"
- bgcolor="#F0F0F0">
- <tr>
- <td>
-<pre>
-#!/path/to/bin/perl
-##
-## txt2dbm -- convert txt map to dbm format
-##
-
-use NDBM_File;
-use Fcntl;
-
-($txtmap, $dbmmap) = @ARGV;
-
-open(TXT, "&lt;$txtmap") or die "Couldn't open $txtmap!\n";
-tie (%DB, 'NDBM_File', $dbmmap,O_RDWR|O_TRUNC|O_CREAT, 0644) or die "Couldn't create $dbmmap!\n";
-
-while (&lt;TXT&gt;) {
- next if (/^\s*#/ or /^\s*$/);
- $DB{$1} = $2 if (/^\s*(\S+)\s+(\S+)/);
-}
-
-untie %DB;
-close(TXT);
-</pre>
- </td>
- </tr>
- </table>
-
- <table border="0" cellspacing="1" cellpadding="5"
- bgcolor="#F0F0F0">
- <tr>
- <td>
-<pre>
-$ txt2dbm map.txt map.db
-</pre>
- </td>
- </tr>
- </table>
- </li>
-
- <li>
- <strong>Internal Function</strong><br />
- MapType: <code>int</code>, MapSource: Internal Apache
- function
-
- <p>Here the source is an internal Apache function.
- Currently you cannot create your own, but the following
- functions already exists:</p>
-
- <ul>
- <li><strong>toupper</strong>:<br />
- Converts the looked up key to all upper case.</li>
-
- <li><strong>tolower</strong>:<br />
- Converts the looked up key to all lower case.</li>
-
- <li><strong>escape</strong>:<br />
- Translates special characters in the looked up key to
- hex-encodings.</li>
-
- <li><strong>unescape</strong>:<br />
- Translates hex-encodings in the looked up key back to
- special characters.</li>
- </ul>
- </li>
-
- <li>
- <strong>External Rewriting Program</strong><br />
- MapType: <code>prg</code>, MapSource: Unix filesystem
- path to valid regular file
-
- <p>Here the source is a program, not a map file. To
- create it you can use the language of your choice, but
- the result has to be a executable (<em>i.e.</em>, either
- object-code or a script with the magic cookie trick
- '<code>#!/path/to/interpreter</code>' as the first
- line).</p>
-
- <p>This program is started once at startup of the Apache
- servers and then communicates with the rewriting engine
- over its <code>stdin</code> and <code>stdout</code>
- file-handles. For each map-function lookup it will
- receive the key to lookup as a newline-terminated string
- on <code>stdin</code>. It then has to give back the
- looked-up value as a newline-terminated string on
- <code>stdout</code> or the four-character string
- ``<code>NULL</code>'' if it fails (<em>i.e.</em>, there
- is no corresponding value for the given key). A trivial
- program which will implement a 1:1 map (<em>i.e.</em>,
- key == value) could be:</p>
-
- <table border="0" cellspacing="1" cellpadding="5"
- bgcolor="#F0F0F0">
- <tr>
- <td>
-<pre>
-#!/usr/bin/perl
-$| = 1;
-while (&lt;STDIN&gt;) {
- # ...put here any transformations or lookups...
- print $_;
-}
-</pre>
- </td>
- </tr>
- </table>
-
- <p>But be very careful:<br />
- </p>
-
- <ol>
- <li>``<em>Keep it simple, stupid</em>'' (KISS), because
- if this program hangs it will hang the Apache server
- when the rule occurs.</li>
-
- <li>Avoid one common mistake: never do buffered I/O on
- <code>stdout</code>! This will cause a deadloop! Hence
- the ``<code>$|=1</code>'' in the above example...</li>
-
- <li>Use the <samp>RewriteLock</samp> directive to
- define a lockfile mod_rewrite can use to synchronize
- the communication to the program. By default no such
- synchronization takes place.</li>
- </ol>
- </li>
- </ul>
- The <code>RewriteMap</code> directive can occur more than
- once. For each mapping-function use one
- <code>RewriteMap</code> directive to declare its rewriting
- mapfile. While you cannot <strong>declare</strong> a map in
- per-directory context it is of course possible to
- <strong>use</strong> this map in per-directory context.
-
- <table width="70%" border="0" bgcolor="#E0E0F0"
- cellspacing="0" cellpadding="10">
- <tr>
- <td><strong>Note:</strong> For plain text and DBM format
- files the looked-up keys are cached in-core until the
- <code>mtime</code> of the mapfile changes or the server
- does a restart. This way you can have map-functions in
- rules which are used for <strong>every</strong> request.
- This is no problem, because the external lookup only
- happens once!</td>
- </tr>
- </table>
- <hr noshade="noshade" size="1" />
-
- <h3><a id="RewriteBase"
- name="RewriteBase">RewriteBase</a></h3>
- <a href="directive-dict.html#Syntax"
- rel="Help"><strong>Syntax:</strong></a> RewriteBase
- <em>URL-path</em><br />
- <a href="directive-dict.html#Default"
- rel="Help"><strong>Default:</strong></a> <em>default is the
- physical directory path</em><br />
- <a href="directive-dict.html#Context"
- rel="Help"><strong>Context:</strong></a> directory,
- .htaccess<br />
- <a href="directive-dict.html#Override"
- rel="Help"><strong>Override:</strong></a>
- <em>FileInfo</em><br />
- <a href="directive-dict.html#Status"
- rel="Help"><strong>Status:</strong></a> Extension<br />
- <a href="directive-dict.html#Module"
- rel="Help"><strong>Module:</strong></a> mod_rewrite.c<br />
- <a href="directive-dict.html#Compatibility"
- rel="Help"><strong>Compatibility:</strong></a> Apache
- 1.2<br />
-
-
- <p>The <code>RewriteBase</code> directive explicitly sets the
- base URL for per-directory rewrites. As you will see below,
- <code>RewriteRule</code> can be used in per-directory config
- files (<code>.htaccess</code>). There it will act locally,
- <em>i.e.</em>, the local directory prefix is stripped at this
- stage of processing and your rewriting rules act only on the
- remainder. At the end it is automatically added back to the
- path.</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>But at most websites URLs are NOT
- directly related to physical filename paths, so this
- assumption will usually be wrong!</strong> There you have to
- use the <code>RewriteBase</code> directive to specify the
- correct URL-prefix.</p>
-
- <table width="70%" border="0" bgcolor="#E0E0F0"
- cellspacing="0" cellpadding="10">
- <tr>
- <td><strong>Notice:</strong> If your webserver's URLs are
- <strong>not</strong> directly related to physical file
- paths, you have to use <code>RewriteBase</code> in every
- <code>.htaccess</code> files where you want to use
- <code>RewriteRule</code> directives.</td>
- </tr>
- </table>
-
- <p><strong>Example:</strong></p>
-
- <blockquote>
- Assume the following per-directory config file:
-
- <table border="0" cellspacing="1" cellpadding="5"
- bgcolor="#F0F0F0">
- <tr>
- <td>
-<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>
-#
-
-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
-</pre>
- </td>
- </tr>
- </table>
-
- <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>
-
- <table width="70%" border="0" bgcolor="#E0E0F0"
- cellspacing="0" cellpadding="10">
- <tr>
- <td>
- <font size="-1"><strong>Note - For Apache
- hackers:</strong><br />
- The following list gives detailed information about
- the internal processing steps:</font>
-<pre>
-<font size="-1">Request:
- /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)
-
-Result:
- /abc/def/newstuff.html
-</font>
-</pre>
- <font size="-1">This seems very complicated but is
- the correct Apache internal processing, because the
- per-directory rewriting comes too late in the
- process. So, when it occurs the (rewritten) request
- has to be re-injected into the Apache kernel! BUT:
- While this seems like a serious overhead, it really
- isn't, because this re-injection happens fully
- internally to the Apache server and the same
- procedure is used by many other operations inside
- Apache. So, you can be sure the design and
- implementation is correct.</font>
- </td>
- </tr>
- </table>
- </blockquote>
- <hr noshade="noshade" size="1" />
-
- <h3><a id="RewriteCond"
- name="RewriteCond">RewriteCond</a></h3>
- <a href="directive-dict.html#Syntax"
- rel="Help"><strong>Syntax:</strong></a> RewriteCond
- <em>TestString</em> <em>CondPattern</em><br />
- <a href="directive-dict.html#Default"
- rel="Help"><strong>Default:</strong></a> <em>None</em><br />
- <a href="directive-dict.html#Context"
- rel="Help"><strong>Context:</strong></a> server config,
- virtual host, directory, .htaccess<br />
- <a href="directive-dict.html#Override"
- rel="Help"><strong>Override:</strong></a>
- <em>FileInfo</em><br />
- <a href="directive-dict.html#Status"
- rel="Help"><strong>Status:</strong></a> Extension<br />
- <a href="directive-dict.html#Module"
- rel="Help"><strong>Module:</strong></a> mod_rewrite.c<br />
- <a href="directive-dict.html#Compatibility"
- rel="Help"><strong>Compatibility:</strong></a> Apache 1.2
- (partially), Apache 1.3<br />
-
-
- <p>The <code>RewriteCond</code> directive defines a rule
- condition. Precede a <code>RewriteRule</code> directive with
- one or more <code>RewriteCond</code> directives. The
- following rewriting rule is only used if its pattern matches
- the current state of the URI <strong>and</strong> if these
- additional conditions apply too.</p>
-
- <p><em>TestString</em> is a string which can contains the
- following expanded constructs in addition to plain text:</p>
-
- <ul>
- <li>
- <strong>RewriteRule backreferences</strong>: These are
- backreferences of the form
-
- <blockquote>
- <strong><code>$N</code></strong>
- </blockquote>
- (0 &lt;= N &lt;= 9) which provide access to the grouped
- parts (parenthesis!) of the pattern from the
- corresponding <code>RewriteRule</code> directive (the one
- following the current bunch of <code>RewriteCond</code>
- directives).
- </li>
-
- <li>
- <strong>RewriteCond backreferences</strong>: These are
- backreferences of the form
-
- <blockquote>
- <strong><code>%N</code></strong>
- </blockquote>
- (1 &lt;= N &lt;= 9) which provide access to the grouped
- parts (parentheses!) of the pattern from the last matched
- <code>RewriteCond</code> directive in the current bunch
- of conditions.
- </li>
-
- <li>
- <strong>RewriteMap expansions</strong>: These are
- expansions of the form
-
- <blockquote>
- <strong><code>${mapname:key|default}</code></strong>
- </blockquote>
- See <a href="#mapfunc">the documentation for
- RewriteMap</a> for more details.
- </li>
-
- <li>
- <strong>Server-Variables</strong>: These are variables of
- the form
-
- <blockquote>
- <strong><code>%{</code> <em>NAME_OF_VARIABLE</em>
- <code>}</code></strong>
- </blockquote>
- where <em>NAME_OF_VARIABLE</em> can be a string taken
- from the following list:
-
- <table bgcolor="#F0F0F0" cellspacing="0" cellpadding="5">
- <tr>
- <td valign="TOP">
- <strong>HTTP headers:</strong>
-
- <p><font size="-1">HTTP_USER_AGENT<br />
- HTTP_REFERER<br />
- HTTP_COOKIE<br />
- HTTP_FORWARDED<br />
- HTTP_HOST<br />
- HTTP_PROXY_CONNECTION<br />
- HTTP_ACCEPT<br />
- </font></p>
- </td>
-
- <td valign="TOP">
- <strong>connection &amp; request:</strong>
-
- <p><font size="-1">REMOTE_ADDR<br />
- REMOTE_HOST<br />
- REMOTE_USER<br />
- REMOTE_IDENT<br />
- REQUEST_METHOD<br />
- SCRIPT_FILENAME<br />
- PATH_INFO<br />
- QUERY_STRING<br />
- AUTH_TYPE<br />
- </font></p>
- </td>
- </tr>
-
- <tr>
- <td valign="TOP">
- <strong>server internals:</strong>
-
- <p><font size="-1">DOCUMENT_ROOT<br />
- SERVER_ADMIN<br />
- SERVER_NAME<br />
- SERVER_ADDR<br />
- SERVER_PORT<br />
- SERVER_PROTOCOL<br />
- SERVER_SOFTWARE<br />
- </font></p>
- </td>
-
- <td valign="TOP">
- <strong>system stuff:</strong>
-
- <p><font size="-1">TIME_YEAR<br />
- TIME_MON<br />
- TIME_DAY<br />
- TIME_HOUR<br />
- TIME_MIN<br />
- TIME_SEC<br />
- TIME_WDAY<br />
- TIME<br />
- </font></p>
- </td>
-
- <td valign="TOP">
- <strong>specials:</strong>
-
- <p><font size="-1">API_VERSION<br />
- THE_REQUEST<br />
- REQUEST_URI<br />
- REQUEST_FILENAME<br />
- IS_SUBREQ<br />
- </font></p>
- </td>
- </tr>
- </table>
-
- <table width="70%" border="0" bgcolor="#E0E0F0"
- cellspacing="0" cellpadding="10">
- <tr>
- <td>
- <p><strong>Notice:</strong> These variables all
- correspond to the similarly named HTTP
- MIME-headers, C variables of the Apache server or
- <code>struct tm</code> fields of the Unix system.
- Most are documented elsewhere in the Manual or in
- the CGI specification. Those that are special to
- mod_rewrite include:</p>
-
- <dl>
- <dt><code>IS_SUBREQ</code></dt>
-
- <dd>Will contain the text "true" if the request
- currently being processed is a sub-request,
- "false" otherwise. Sub-requests may be generated
- by modules that need to resolve additional files
- or URIs in order to complete their tasks.</dd>
-
- <dt><code>API_VERSION</code></dt>
-
- <dd>This is the version of the Apache module API
- (the internal interface between server and
- module) in the current httpd build, as defined in
- 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>
- </dl>
- </td>
- </tr>
- </table>
- </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>%{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
- standard <em>Extended 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 <samp>""</samp> (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>
-
- <table width="70%" border="0" bgcolor="#E0E0F0"
- cellspacing="0" cellpadding="10">
- <tr>
- <td><strong>Notice:</strong> All of these tests can
- also be prefixed by an exclamation mark ('!') to
- negate their meaning.</td>
- </tr>
- </table>
- </li>
- </ol>
-
- <p>Additionally you can set special flags for
- <em>CondPattern</em> by appending</p>
-
- <blockquote>
- <strong><code>[</code><em>flags</em><code>]</code></strong>
- </blockquote>
- as the third argument to the <code>RewriteCond</code>
- directive. <em>Flags</em> is a comma-separated list of the
- following flags:
-
- <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:
-
- <blockquote>
-<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>
- </blockquote>
- Without this flag you would have to write the cond/rule
- three times.
- </li>
- </ul>
-
- <p><strong>Example:</strong></p>
-
- <blockquote>
- To rewrite the Homepage of a site according to the
- ``<code>User-Agent:</code>'' header of the request, you can
- use the following:
-
- <blockquote>
-<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>
- </blockquote>
- 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.
- </blockquote>
- <hr noshade="noshade" size="1" />
-
- <h3><a id="RewriteRule"
- name="RewriteRule">RewriteRule</a></h3>
- <a href="directive-dict.html#Syntax"
- rel="Help"><strong>Syntax:</strong></a> RewriteRule
- <em>Pattern</em> <em>Substitution</em><br />
- <a href="directive-dict.html#Default"
- rel="Help"><strong>Default:</strong></a> <em>None</em><br />
- <a href="directive-dict.html#Context"
- rel="Help"><strong>Context:</strong></a> server config,
- virtual host, directory, .htaccess<br />
- <a href="directive-dict.html#Override"
- rel="Help"><strong>Override:</strong></a>
- <em>FileInfo</em><br />
- <a href="directive-dict.html#Status"
- rel="Help"><strong>Status:</strong></a> Extension<br />
- <a href="directive-dict.html#Module"
- rel="Help"><strong>Module:</strong></a> mod_rewrite.c<br />
- <a href="directive-dict.html#Compatibility"
- rel="Help"><strong>Compatibility:</strong></a> Apache 1.2
- (partially), Apache 1.3<br />
-
-
- <p>The <code>RewriteRule</code> directive is the real
- rewriting workhorse. The directive can occur more than once.
- Each directive then defines one single rewriting rule. The
- <strong>definition order</strong> of these rules is
- <strong>important</strong>, because this order is used when
- applying the rules at run-time.</p>
-
- <p><a id="patterns" name="patterns"><em>Pattern</em></a> can
- be (for Apache 1.1.x a System V8 and for Apache 1.2.x and
- later a POSIX) <a id="regexp" name="regexp">regular
- expression</a> which gets applied to the current URL. Here
- ``current'' means the value of the URL when this rule gets
- applied. This may not be the originally requested URL,
- because any number of rules may already
- have matched and made alterations to it.</p>
-
- <p>Some hints about the syntax of regular expressions:</p>
-
- <table bgcolor="#F0F0F0" cellspacing="0" cellpadding="5">
- <tr>
- <td valign="TOP">
-<pre>
-<strong>Text:</strong>
- <strong><code>.</code></strong> Any single character
- <strong><code>[</code></strong>chars<strong><code>]</code></strong> Character class: One of chars
- <strong><code>[^</code></strong>chars<strong><code>]</code></strong> Character class: None of chars
- text1<strong><code>|</code></strong>text2 Alternative: text1 or text2
-
-<strong>Quantifiers:</strong>
- <strong><code>?</code></strong> 0 or 1 of the preceding text
- <strong><code>*</code></strong> 0 or N of the preceding text (N &gt; 0)
- <strong><code>+</code></strong> 1 or N of the preceding text (N &gt; 1)
-
-<strong>Grouping:</strong>
- <strong><code>(</code></strong>text<strong><code>)</code></strong> Grouping of text
- (either to set the borders of an alternative or
- for making backreferences where the <strong>N</strong>th group can
- be used on the RHS of a RewriteRule with <code>$</code><strong>N</strong>)
-
-<strong>Anchors:</strong>
- <strong><code>^</code></strong> Start of line anchor
- <strong><code>$</code></strong> End of line anchor
-
-<strong>Escaping:</strong>
- <strong><code>\</code></strong>char escape that particular char
- (for instance to specify the chars "<code>.[]()</code>" <em>etc.</em>)
-</pre>
- </td>
- </tr>
- </table>
-
- <p>For more information about regular expressions either have
- a look at your local regex(3) manpage or its
- <code>src/regex/regex.3</code> copy in the Apache 1.3
- distribution. If you are interested in more detailed
- information about regular expressions and their variants
- (POSIX regex, Perl regex, <em>etc.</em>) have a look at the
- following dedicated book on this topic:</p>
-
- <blockquote>
- <em>Mastering Regular Expressions</em><br />
- Jeffrey E.F. Friedl<br />
- Nutshell Handbook Series<br />
- O'Reilly &amp; Associates, Inc. 1997<br />
- ISBN 1-56592-257-3<br />
- </blockquote>
-
- <p>Additionally in mod_rewrite the NOT character
- ('<code>!</code>') is a possible pattern prefix. This gives
- you the ability to negate a pattern; to say, for instance:
- ``<em>if the current URL does <strong>NOT</strong> match this
- pattern</em>''. This can be used for exceptional cases, where
- it is easier to match the negative pattern, or as a last
- default rule.</p>
-
- <table width="70%" border="0" bgcolor="#E0E0F0"
- cellspacing="0" cellpadding="10">
- <tr>
- <td><strong>Notice:</strong> When using the NOT character
- to negate a pattern you cannot have grouped wildcard
- parts in the pattern. This is impossible because when the
- pattern does NOT match, there are no contents for the
- groups. In consequence, if negated patterns are used, you
- cannot use <code>$N</code> in the substitution
- string!</td>
- </tr>
- </table>
-
- <p><a id="rhs" name="rhs"><em>Substitution</em></a> of a
- rewriting rule is the string which is substituted for (or
- replaces) the original URL for which <em>Pattern</em>
- matched. Beside plain text you can use</p>
-
- <ol>
- <li>back-references <code>$N</code> to the RewriteRule
- pattern</li>
-
- <li>back-references <code>%N</code> to the last matched
- RewriteCond pattern</li>
-
- <li>server-variables as in rule condition test-strings
- (<code>%{VARNAME}</code>)</li>
-
- <li><a href="#mapfunc">mapping-function</a> calls
- (<code>${mapname:key|default}</code>)</li>
- </ol>
- Back-references are <code>$</code><strong>N</strong>
- (<strong>N</strong>=0..9) identifiers which will be replaced
- by the contents of the <strong>N</strong>th group of the
- matched <em>Pattern</em>. The server-variables are the same
- as for the <em>TestString</em> of a <code>RewriteCond</code>
- directive. The mapping-functions come from the
- <code>RewriteMap</code> directive and are explained there.
- These three types of variables are expanded in the order of
- the above list.
-
- <p>As already mentioned above, all the rewriting rules are
- applied to the <em>Substitution</em> (in the order of
- definition in the config file). The URL is <strong>completely
- replaced</strong> by the <em>Substitution</em> and the
- rewriting process goes on until there are no more rules
- unless explicitly terminated by a
- <code><strong>L</strong></code> flag - see below.</p>
-
- <p>There is a special substitution string named
- '<code>-</code>' which means: <strong>NO
- substitution</strong>! Sounds silly? No, it is useful to
- provide rewriting rules which <strong>only</strong> match
- some URLs but do no substitution, <em>e.g.</em>, in
- conjunction with the <strong>C</strong> (chain) flag to be
- able to have more than one pattern to be applied before a
- substitution occurs.</p>
-
- <p>One more note: You can even create URLs in the
- substitution string containing a query string part. Just use
- a question mark inside the substitution string to indicate
- that the following stuff should be re-injected into the
- QUERY_STRING. When you want to erase an existing query
- string, end the substitution string with just the question
- mark.</p>
-
- <table width="70%" border="0" bgcolor="#E0E0F0"
- cellspacing="0" cellpadding="10">
- <tr>
- <td><strong>Note</strong>: There is a special feature:
- When you prefix a substitution field with
- <code>http://</code><em>thishost</em>[<em>:thisport</em>]
- then <strong>mod_rewrite</strong> automatically strips it
- out. This auto-reduction on implicit external redirect
- URLs is a useful and important feature when used in
- combination with a mapping-function which generates the
- hostname part. Have a look at the first example in the
- example section below to understand this.</td>
- </tr>
- </table>
-
- <table width="70%" border="0" bgcolor="#E0E0F0"
- cellspacing="0" cellpadding="10">
- <tr>
- <td><strong>Remember:</strong> An unconditional external
- redirect to your own server will not work with the prefix
- <code>http://thishost</code> because of this feature. To
- achieve such a self-redirect, you have to use the
- <strong>R</strong>-flag (see below).</td>
- </tr>
- </table>
-
- <p>Additionally you can set special flags for
- <em>Substitution</em> by appending</p>
-
- <blockquote>
- <strong><code>[</code><em>flags</em><code>]</code></strong>
- </blockquote>
- as the third argument to the <code>RewriteRule</code>
- directive. <em>Flags</em> is a comma-separated list of the
- following flags:
-
- <ul>
- <li>
- '<strong><code>redirect|R</code>
- [=<em>code</em>]</strong>' (force <a id="redirect"
- name="redirect"><strong>r</strong>edirect</a>)<br />
- Prefix <em>Substitution</em> with
- <code>http://thishost[:thisport]/</code> (which makes the
- new URL a URI) to force a external redirection. If no
- <em>code</em> is given a HTTP response of 302 (MOVED
- TEMPORARILY) is used. If you want to use other response
- codes in the range 300-400 just specify them as a number
- or use one of the following symbolic names:
- <code>temp</code> (default), <code>permanent</code>,
- <code>seeother</code>. Use it for rules which should
- canonicalize the URL and give it back to the client,
- <em>e.g.</em>, translate ``<code>/~</code>'' into
- ``<code>/u/</code>'' or always append a slash to
- <code>/u/</code><em>user</em>, etc.<br />
-
-
- <p><strong>Note:</strong> When you use this flag, make
- sure that the substitution field is a valid URL! If not,
- you are redirecting to an invalid location! And remember
- that this flag itself only prefixes the URL with
- <code>http://thishost[:thisport]/</code>, rewriting
- continues. Usually you also want to stop and do the
- redirection immediately. To stop the rewriting you also
- have to provide the 'L' flag.</p>
- </li>
-
- <li>'<strong><code>forbidden|F</code></strong>' (force URL
- to be <strong>f</strong>orbidden)<br />
- This forces the current URL to be forbidden,
- <em>i.e.</em>, it immediately sends back a HTTP response of
- 403 (FORBIDDEN). Use this flag in conjunction with
- appropriate RewriteConds to conditionally block some
- URLs.</li>
-
- <li>'<strong><code>gone|G</code></strong>' (force URL to be
- <strong>g</strong>one)<br />
- This forces the current URL to be gone, <em>i.e.</em>, it
- immediately sends back a HTTP response of 410 (GONE). Use
- this flag to mark pages which no longer exist as gone.</li>
-
- <li>
- '<strong><code>proxy|P</code></strong>' (force
- <strong>p</strong>roxy)<br />
- This flag forces the substitution part to be internally
- forced as a proxy request and immediately (<em>i.e.</em>,
- rewriting rule processing stops here) put through the <a
- href="mod_proxy.html">proxy module</a>. You have to make
- sure that the substitution string is a valid URI
- (<em>e.g.</em>, typically starting with
- <code>http://</code><em>hostname</em>) which can be
- handled by the Apache proxy module. If not you get an
- error from the proxy module. Use this flag to achieve a
- more powerful implementation of the <a
- href="mod_proxy.html#proxypass">ProxyPass</a> directive,
- to map some remote stuff into the namespace of the local
- server.
-
- <p>Notice: To use this functionality make sure you have
- the proxy module compiled into your Apache server
- program. If you don't know please check whether
- <code>mod_proxy.c</code> is part of the ``<code>httpd
- -l</code>'' output. If yes, this functionality is
- available to mod_rewrite. If not, then you first have to
- rebuild the ``<code>httpd</code>'' program with mod_proxy
- enabled.</p>
- </li>
-
- <li>'<strong><code>last|L</code></strong>'
- (<strong>l</strong>ast rule)<br />
- Stop the rewriting process here and don't apply any more
- rewriting rules. This corresponds to the Perl
- <code>last</code> command or the <code>break</code> command
- from the C language. Use this flag to prevent the currently
- rewritten URL from being rewritten further by following
- rules. For example, use it to rewrite the root-path URL
- ('<code>/</code>') to a real one, <em>e.g.</em>,
- '<code>/e/www/</code>'.</li>
-
- <li>'<strong><code>next|N</code></strong>'
- (<strong>n</strong>ext round)<br />
- Re-run the rewriting process (starting again with the
- first rewriting rule). Here the URL to match is again not
- the original URL but the URL from the last rewriting rule.
- This corresponds to the Perl <code>next</code> command or
- the <code>continue</code> command from the C language. Use
- this flag to restart the rewriting process, <em>i.e.</em>,
- to immediately go to the top of the loop.<br />
- <strong>But be careful not to create an infinite
- loop!</strong></li>
-
- <li>'<strong><code>chain|C</code></strong>'
- (<strong>c</strong>hained with next rule)<br />
- This flag chains the current rule with the next rule
- (which itself can be chained with the following rule,
- <em>etc.</em>). This has the following effect: if a rule
- matches, then processing continues as usual, <em>i.e.</em>,
- the flag has no effect. If the rule does
- <strong>not</strong> match, then all following chained
- rules are skipped. For instance, use it to remove the
- ``<code>.www</code>'' part inside a per-directory rule set
- when you let an external redirect happen (where the
- ``<code>.www</code>'' part should not to occur!).</li>
-
- <li>
- '<strong><code>type|T</code></strong>=<em>MIME-type</em>'
- (force MIME <strong>t</strong>ype)<br />
- Force the MIME-type of the target file to be
- <em>MIME-type</em>. For instance, this can be used to
- simulate the <code>mod_alias</code> directive
- <code>ScriptAlias</code> which internally forces all files
- inside the mapped directory to have a MIME type of
- ``<code>application/x-httpd-cgi</code>''.</li>
-
- <li>
- '<strong><code>nosubreq|NS</code></strong>' (used only if
- <strong>n</strong>o internal
- <strong>s</strong>ub-request)<br />
- This flag forces the rewriting engine to skip a
- rewriting rule if the current request is an internal
- sub-request. For instance, sub-requests occur internally
- in Apache when <code>mod_include</code> tries to find out
- information about possible directory default files
- (<code>index.xxx</code>). On sub-requests it is not
- always useful and even sometimes causes a failure to if
- the complete set of rules are applied. Use this flag to
- exclude some rules.<br />
-
-
- <p>Use the following rule for your decision: whenever you
- prefix some URLs with CGI-scripts to force them to be
- processed by the CGI-script, the chance is high that you
- will run into problems (or even overhead) on
- sub-requests. In these cases, use this flag.</p>
- </li>
-
- <li>'<strong><code>nocase|NC</code></strong>'
- (<strong>n</strong>o <strong>c</strong>ase)<br />
- This makes the <em>Pattern</em> case-insensitive,
- <em>i.e.</em>, there is no difference between 'A-Z' and
- 'a-z' when <em>Pattern</em> is matched against the current
- URL.</li>
-
- <li>'<strong><code>qsappend|QSA</code></strong>'
- (<strong>q</strong>uery <strong>s</strong>tring
- <strong>a</strong>ppend)<br />
- This flag forces the rewriting engine to append a query
- string part in the substitution string to the existing one
- instead of replacing it. Use this when you want to add more
- data to the query string via a rewrite rule.</li>
-
- <li>
- '<strong><code>noescape|NE</code></strong>'
- (<strong>n</strong>o URI <strong>e</strong>scaping of
- output)<br />
- This flag keeps mod_rewrite from applying the usual URI
- escaping rules to the result of a rewrite. Ordinarily,
- special characters (such as '%', '$', ';', and so on)
- will be escaped into their hexcode equivalents ('%25',
- '%24', and '%3B', respectively); this flag prevents this
- from being done. This allows percent symbols to appear in
- the output, as in
-<pre>
- RewriteRule /foo/(.*) /bar?arg=P1\%3d$1 [R,NE]
-
-</pre>
- which would turn '<code>/foo/zed</code>' into a safe
- request for '<code>/bar?arg=P1=zed</code>'.
-
- <table width="70%" border="0" bgcolor="#E0E0F0"
- cellspacing="0" cellpadding="10">
- <tr>
- <td><strong>Notice:</strong> The
- <code>noescape</code> flag is only available with
- Apache 1.3.20 and later versions.</td>
- </tr>
- </table>
- </li>
-
- <li>
- '<strong><code>passthrough|PT</code></strong>'
- (<strong>p</strong>ass <strong>t</strong>hrough to next
- handler)<br />
- This flag forces the rewriting engine to set the
- <code>uri</code> field of the internal
- <code>request_rec</code> structure to the value of the
- <code>filename</code> field. This flag is just a hack to
- be able to post-process the output of
- <code>RewriteRule</code> directives by
- <code>Alias</code>, <code>ScriptAlias</code>,
- <code>Redirect</code>, <em>etc.</em> directives from
- other URI-to-filename translators. A trivial example to
- show the semantics: If you want to rewrite
- <code>/abc</code> to <code>/def</code> via the rewriting
- engine of <code>mod_rewrite</code> and then
- <code>/def</code> to <code>/ghi</code> with
- <code>mod_alias</code>:
-<pre>
- RewriteRule ^/abc(.*) /def$1 [PT]
- Alias /def /ghi
-
-</pre>
- If you omit the <code>PT</code> flag then
- <code>mod_rewrite</code> will do its job fine,
- <em>i.e.</em>, it rewrites <code>uri=/abc/...</code> to
- <code>filename=/def/...</code> as a full API-compliant
- URI-to-filename translator should do. Then
- <code>mod_alias</code> comes and tries to do a
- URI-to-filename transition which will not work.
-
- <p>Note: <strong>You have to use this flag if you want to
- intermix directives of different modules which contain
- URL-to-filename translators</strong>. The typical example
- is the use of <code>mod_alias</code> and
- <code>mod_rewrite</code>..</p>
- </li>
-
- <li>'<strong><code>skip|S</code></strong>=<em>num</em>'
- (<strong>s</strong>kip next rule(s))<br />
- This flag forces the rewriting engine to skip the next
- <em>num</em> rules in sequence when the current rule
- matches. Use this to make pseudo if-then-else constructs:
- The last rule of the then-clause becomes
- <code>skip=N</code> where N is the number of rules in the
- else-clause. (This is <strong>not</strong> the same as the
- 'chain|C' flag!)</li>
-
- <li>
- '<strong><code>env|E=</code></strong><em>VAR</em>:<em>VAL</em>'
- (set <strong>e</strong>nvironment variable)<br />
- This forces an environment variable named <em>VAR</em> to
- be set to the value <em>VAL</em>, where <em>VAL</em> can
- contain regexp backreferences <code>$N</code> and
- <code>%N</code> which will be expanded. You can use this
- flag more than once to set more than one variable. The
- variables can be later dereferenced in many situations, but
- usually from within XSSI (via <code>&lt;!--#echo
- var="VAR"--&gt;</code>) or CGI (<em>e.g.</em>
- <code>$ENV{'VAR'}</code>). Additionally you can dereference
- it in a following RewriteCond pattern via
- <code>%{ENV:VAR}</code>. Use this to strip but remember
- information from URLs.</li>
- </ul>
-
- <table width="70%" border="0" bgcolor="#E0E0F0"
- cellspacing="0" cellpadding="10">
- <tr>
- <td>
- <strong>Note:</strong> Never forget that
- <em>Pattern</em> is applied to a complete URL in
- per-server configuration files. <strong>But in
- per-directory configuration files, the per-directory
- prefix (which always is the same for a specific
- directory!) is automatically <em>removed</em> for the
- pattern matching and automatically <em>added</em> after
- the substitution has been done.</strong> This feature
- is essential for many sorts of rewriting, because
- without this prefix stripping you have to match the
- parent directory which is not always possible.
-
- <p>There is one exception: If a substitution string
- starts with ``<code>http://</code>'' then the directory
- prefix will <strong>not</strong> be added and an
- external redirect or proxy throughput (if flag
- <strong>P</strong> is used!) is forced!</p>
- </td>
- </tr>
- </table>
-
- <table width="70%" border="0" bgcolor="#E0E0F0"
- cellspacing="0" cellpadding="10">
- <tr>
- <td><strong>Note:</strong> To enable the rewriting engine
- for per-directory configuration files you need to set
- ``<code>RewriteEngine On</code>'' in these files
- <strong>and</strong> ``<code>Options
- FollowSymLinks</code>'' must be enabled. If your
- administrator has disabled override of
- <code>FollowSymLinks</code> for a user's directory, then
- you cannot use the rewriting engine. This restriction is
- needed for security reasons.</td>
- </tr>
- </table>
-
- <p>Here are all possible substitution combinations and their
- meanings:</p>
-
- <p><strong>Inside per-server configuration
- (<code>httpd.conf</code>)<br />
- for request ``<code>GET
- /somepath/pathinfo</code>'':</strong><br />
- </p>
-
- <table bgcolor="#F0F0F0" cellspacing="0" cellpadding="5">
- <tr>
- <td>
-<pre>
-<strong>Given Rule</strong> <strong>Resulting Substitution</strong>
----------------------------------------------- ----------------------------------
-^/somepath(.*) otherpath$1 not supported, because invalid!
-
-^/somepath(.*) otherpath$1 [R] not supported, because invalid!
-
-^/somepath(.*) otherpath$1 [P] not supported, because invalid!
----------------------------------------------- ----------------------------------
-^/somepath(.*) /otherpath$1 /otherpath/pathinfo
-
-^/somepath(.*) /otherpath$1 [R] http://thishost/otherpath/pathinfo
- via external redirection
-
-^/somepath(.*) /otherpath$1 [P] not supported, because silly!
----------------------------------------------- ----------------------------------
-^/somepath(.*) http://thishost/otherpath$1 /otherpath/pathinfo
-
-^/somepath(.*) http://thishost/otherpath$1 [R] http://thishost/otherpath/pathinfo
- via external redirection
-
-^/somepath(.*) http://thishost/otherpath$1 [P] not supported, because silly!
----------------------------------------------- ----------------------------------
-^/somepath(.*) http://otherhost/otherpath$1 http://otherhost/otherpath/pathinfo
- via external redirection
-
-^/somepath(.*) http://otherhost/otherpath$1 [R] http://otherhost/otherpath/pathinfo
- via external redirection
- (the [R] flag is redundant)
-
-^/somepath(.*) http://otherhost/otherpath$1 [P] http://otherhost/otherpath/pathinfo
- via internal proxy
-</pre>
- </td>
- </tr>
- </table>
-
- <p><strong>Inside per-directory configuration for
- <code>/somepath</code><br />
- (<em>i.e.</em>, file <code>.htaccess</code> in dir
- <code>/physical/path/to/somepath</code> containing
- <code>RewriteBase /somepath</code>)<br />
- for request ``<code>GET
- /somepath/localpath/pathinfo</code>'':</strong><br />
- </p>
-
- <table bgcolor="#F0F0F0" cellspacing="0" cellpadding="5">
- <tr>
- <td>
-<pre>
-<strong>Given Rule</strong> <strong>Resulting Substitution</strong>
----------------------------------------------- ----------------------------------
-^localpath(.*) otherpath$1 /somepath/otherpath/pathinfo
-
-^localpath(.*) otherpath$1 [R] http://thishost/somepath/otherpath/pathinfo
- via external redirection
-
-^localpath(.*) otherpath$1 [P] not supported, because silly!
----------------------------------------------- ----------------------------------
-^localpath(.*) /otherpath$1 /otherpath/pathinfo
-
-^localpath(.*) /otherpath$1 [R] http://thishost/otherpath/pathinfo
- via external redirection
-
-^localpath(.*) /otherpath$1 [P] not supported, because silly!
----------------------------------------------- ----------------------------------
-^localpath(.*) http://thishost/otherpath$1 /otherpath/pathinfo
-
-^localpath(.*) http://thishost/otherpath$1 [R] http://thishost/otherpath/pathinfo
- via external redirection
-
-^localpath(.*) http://thishost/otherpath$1 [P] not supported, because silly!
----------------------------------------------- ----------------------------------
-^localpath(.*) http://otherhost/otherpath$1 http://otherhost/otherpath/pathinfo
- via external redirection
-
-^localpath(.*) http://otherhost/otherpath$1 [R] http://otherhost/otherpath/pathinfo
- via external redirection
- (the [R] flag is redundant)
-
-^localpath(.*) http://otherhost/otherpath$1 [P] http://otherhost/otherpath/pathinfo
- via internal proxy
-</pre>
- </td>
- </tr>
- </table>
-
- <p><strong>Example:</strong></p>
-
- <blockquote>
- We want to rewrite URLs of the form
-
- <blockquote>
- <code>/</code> <em>Language</em> <code>/~</code>
- <em>Realname</em> <code>/.../</code> <em>File</em>
- </blockquote>
- into
-
- <blockquote>
- <code>/u/</code> <em>Username</em> <code>/.../</code>
- <em>File</em> <code>.</code> <em>Language</em>
- </blockquote>
-
- <p>We take the rewrite mapfile from above and save it under
- <code>/path/to/file/map.txt</code>. Then we only have to
- add the following lines to the Apache server configuration
- file:</p>
-
- <blockquote>
-<pre>
-RewriteLog /path/to/file/rewrite.log
-RewriteMap real-to-user txt:/path/to/file/map.txt
-RewriteRule ^/([^/]+)/~([^/]+)/(.*)$ /u/${real-to-user:$2|nobody}/$3.$1
-</pre>
- </blockquote>
- </blockquote>
- <hr noshade="noshade" size="1" />
-
- <center>
- <h1><a id="Miscelleneous"
- name="Miscelleneous">Miscellaneous</a></h1>
- </center>
- <hr noshade="noshade" size="1" />
-
- <h2><a id="EnvVar" name="EnvVar">Environment
- Variables</a></h2>
- This module keeps track of two additional (non-standard)
- CGI/SSI environment variables named <code>SCRIPT_URL</code>
- and <code>SCRIPT_URI</code>. These contain the
- <em>logical</em> Web-view to the current resource, while the
- standard CGI/SSI variables <code>SCRIPT_NAME</code> and
- <code>SCRIPT_FILENAME</code> contain the <em>physical</em>
- System-view.
-
- <p>Notice: These variables hold the URI/URL <em>as they were
- initially requested</em>, <em>i.e.</em>, <em>before</em> any
- rewriting. This is important because the rewriting process is
- primarily used to rewrite logical URLs to physical
- pathnames.</p>
-
- <p><strong>Example:</strong></p>
-
- <blockquote>
-<pre>
-SCRIPT_NAME=/sw/lib/w3s/tree/global/u/rse/.www/index.html
-SCRIPT_FILENAME=/u/rse/.www/index.html
-SCRIPT_URL=/u/rse/
-SCRIPT_URI=http://en1.engelschall.com/u/rse/
-</pre>
- </blockquote>
- <hr noshade="noshade" size="1" />
-
- <h2><a id="Solutions" name="Solutions">Practical
- Solutions</a></h2>
- We also have an <a href="../misc/rewriteguide.html">URL
- Rewriting Guide</a> available, which provides a collection of
- practical solutions for URL-based problems. There you can
- find real-life rulesets and additional information about
- mod_rewrite.
- </blockquote>
- <hr />
-
- <h3 align="CENTER">Apache HTTP Server Version 1.3</h3>
- <a href="./"><img src="../images/index.gif" alt="Index" /></a>
- <a href="../"><img src="../images/home.gif" alt="Home" /></a>
-
- <!-- page indentation -->
- <!--/%hypertext -->
- </body>
-</html>
-