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diff --git a/usr.sbin/httpd/htdocs/manual/mod/mod_rewrite.html b/usr.sbin/httpd/htdocs/manual/mod/mod_rewrite.html deleted file mode 100644 index 341426057cc..00000000000 --- a/usr.sbin/httpd/htdocs/manual/mod/mod_rewrite.html +++ /dev/null @@ -1,2117 +0,0 @@ -<!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, $dbmmap) = @ARGV; - -open(TXT, "<$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 $dbmmap!\n"; - -while (<TXT>) { - next if (/^\s*#/ or /^\s*$/); - $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 (<STDIN>) { - # ...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 -> /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 -</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>$N</code></strong> - </blockquote> - (0 <= N <= 9) which provide access to the grouped - parts (parenthesis!) of the pattern from the - corresponding <code>RewriteRule</code> directive (the one - following the current bunch of <code>RewriteCond</code> - directives). - </li> - - <li> - <strong>RewriteCond backreferences</strong>: These are - backreferences of the form - - <blockquote> - <strong><code>%N</code></strong> - </blockquote> - (1 <= N <= 9) which provide access to the grouped - parts (parentheses!) of the pattern from the last matched - <code>RewriteCond</code> directive in the current bunch - of conditions. - </li> - - <li> - <strong>RewriteMap expansions</strong>: These are - expansions of the form - - <blockquote> - <strong><code>${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 & 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><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>>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 > 0) - <strong><code>+</code></strong> 1 or N of the preceding text (N > 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 & 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$1 [PT] - Alias /def /ghi - -</pre> - If you omit the <code>PT</code> flag then - <code>mod_rewrite</code> will do its job fine, - <em>i.e.</em>, it rewrites <code>uri=/abc/...</code> to - <code>filename=/def/...</code> as a full API-compliant - URI-to-filename translator should do. Then - <code>mod_alias</code> comes and tries to do a - URI-to-filename transition which will not work. - - <p>Note: <strong>You have to use this flag if you want to - intermix directives of different modules which contain - URL-to-filename translators</strong>. The typical example - is the use of <code>mod_alias</code> and - <code>mod_rewrite</code>..</p> - - <table width="70%" border="0" bgcolor="#E0E0F0" - cellspacing="0" cellpadding="10"> - <tr> - <td><font size="-1"><strong>Note - For Apache - hackers:</strong><br /> - If the current Apache API had a filename-to-filename - hook additionally to the URI-to-filename hook then we - wouldn't need this flag! But without such a hook this - flag is the only solution. The Apache Group has - discussed this problem and will add such a hook in - Apache version 2.0.</font> </td> - </tr> - </table> - </li> - - <li>'<strong><code>skip|S</code></strong>=<em>num</em>' - (<strong>s</strong>kip next rule(s))<br /> - This flag forces the rewriting engine to skip the next - <em>num</em> rules in sequence when the current rule - matches. Use this to make pseudo if-then-else constructs: - The last rule of the then-clause becomes - <code>skip=N</code> where N is the number of rules in the - else-clause. (This is <strong>not</strong> the same as the - 'chain|C' flag!)</li> - - <li> - '<strong><code>env|E=</code></strong><em>VAR</em>:<em>VAL</em>' - (set <strong>e</strong>nvironment variable)<br /> - This forces an environment variable named <em>VAR</em> to - be set to the value <em>VAL</em>, where <em>VAL</em> can - contain regexp backreferences <code>$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><!--#echo - var="VAR"--></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> - |