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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 index 44ed3239cf2..118ea068ccd 100644 --- a/usr.sbin/httpd/htdocs/manual/mod/mod_rewrite.html +++ b/usr.sbin/httpd/htdocs/manual/mod/mod_rewrite.html @@ -2,10 +2,10 @@ <!--%hypertext --> <!-- mod_rewrite.html --> <!-- Documentation for the mod_rewrite Apache module --> -<html> -<head> -<title>Apache module mod_rewrite</title> -</head> +<HTML> +<HEAD> +<TITLE>Apache module mod_rewrite</TITLE> +</HEAD> <!-- Background white, links blue (unvisited), navy (visited), red (active) --> <BODY @@ -15,305 +15,777 @@ VLINK="#000080" ALINK="#FF0000" > +<BLOCKQUOTE><!-- page indentation --> <DIV ALIGN="CENTER"> <IMG SRC="../images/sub.gif" ALT="[APACHE DOCUMENTATION]"> <H3> - Apache HTTP Server Version 1.2 + Apache HTTP Server Version 1.3 </H3> </DIV> -<h1 ALIGN="CENTER">Module mod_rewrite</h1> - -This module is contained in the <code>mod_rewrite.c</code> file, with Apache -1.2 and later. It provides a rule-based rewriting engine to rewrite requested -URLs on the fly. <code>mod_rewrite</code> is not compiled into the server by -default. To use <code>mod_rewrite</code> you have to enable the following line -in the server build Configuration file: -<pre> - Module rewrite_module mod_rewrite.o -</pre> - -<h2>Summary</h2> - -This module uses a rule-based rewriting engine (based on a -regular-expression parser) to rewrite requested URLs on the fly. - -<p> -It supports an unlimited number of additional rule conditions (which can -operate on a lot of variables, including HTTP headers) for granular -matching and external database lookups (either via plain text -tables, DBM hash files or external processes) for advanced URL -substitution. - -<p> -It operates on the full URLs (including the PATH_INFO part) both in per-server -context (httpd.conf) and per-dir context (.htaccess) and even can generate -QUERY_STRING parts on result. The rewritten result can lead to internal -sub-processing, external request redirection or to internal proxy throughput. - -<p> -This module was originally written in April 1996 and -gifted exclusively to the The Apache Group in July 1997 by -<p> -<blockquote> - <i>Ralf S. Engelschall</i><br> - <a href="mailto:rse@engelschall.com"><tt>rse@engelschall.com</tt></a><br> - <a href="http://www.engelschall.com/"><tt>www.engelschall.com</tt></a> -</blockquote> - -<!--%hypertext --> -<HR> -<!--/%hypertext --> - -<p> -<h2>Directives</h2> - -<ul> - <li><a href="#RewriteEngine">RewriteEngine</a> - <li><a href="#RewriteOptions">RewriteOptions</a> - <li><a href="#RewriteLog">RewriteLog</a> - <li><a href="#RewriteLogLevel">RewriteLogLevel</a> - <li><a href="#RewriteMap">RewriteMap</a> - <li><a href="#RewriteBase">RewriteBase</a> - <li><a href="#RewriteCond">RewriteCond</a> - <li><a href="#RewriteRule">RewriteRule</a> -</ul> - -<!--%hypertext --> -<hr> -<!--/%hypertext --> - - -<center> -<a name="Configuration"> -<h1>Configuration Directives</h1> -</a> -</center> +<BR> +<H1 ALIGN="CENTER">Module mod_rewrite<BR>URL Rewriting Engine</H1> + +This module is contained in the <CODE>mod_rewrite.c</CODE> file, with Apache +1.2 and later. It provides a rule-based rewriting engine to rewrite requested +URLs on the fly. It is not compiled into the server by default. To use +<CODE>mod_rewrite</CODE> you have to enable the following line in the server +build <CODE>Configuration</CODE> file: +<PRE> + AddModule modules/standard/mod_rewrite.o +</PRE> + +<P> +<HR 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> +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 even can 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> +But all this functionality and flexibility has its drawback: complexity. So +don't expect to understand this module in it's whole in just one day. + +<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> + +<P> +<HR NOSHADE SIZE=1> + +<H2>Table Of Contents</H2> + +<P> +<STRONG>Internal Processing</STRONG> +<UL> + <LI><A HREF="#InternalAPI">API Phases</A> + <LI><A HREF="#InternalRuleset">Ruleset Processing</A> + <LI><A HREF="#InternalBackRefs">Regex Back-Reference Availability</A> +</UL> +<P> +<STRONG>Configuration Directives</STRONG> +<UL> + <LI><A HREF="#RewriteEngine">RewriteEngine</A> + <LI><A HREF="#RewriteOptions">RewriteOptions</A> + <LI><A HREF="#RewriteLog">RewriteLog</A> + <LI><A HREF="#RewriteLogLevel">RewriteLogLevel</A> + <LI><A HREF="#RewriteLock">RewriteLock</A> + <LI><A HREF="#RewriteMap">RewriteMap</A> + <LI><A HREF="#RewriteBase">RewriteBase</A> + <LI><A HREF="#RewriteCond">RewriteCond</A> + <LI><A HREF="#RewriteRule">RewriteRule</A> +</UL> +<STRONG>Miscellaneous</STRONG> +<UL> + <LI><A HREF="#EnvVar">Environment Variables</A> + <LI><A HREF="#Solutions">Practical Solutions</A> +</UL> + +<P> +<HR NOSHADE SIZE=1> + +<CENTER> +<H1><A NAME="Internal">Internal Processing</A></H1> +</CENTER> + +<P> +<HR 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. + +<H2><A 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 was read and 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>) where read, +but before the content handler is activated. + +<P> +So, after a request comes in and Apache has determined the corresponding +server (or virtual server) the rewriting engine start 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 either rewrites URLs 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 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: + +<OL> +<LI>The API currently provides only a URL-to-filename hook. Although + mod_rewrite rewrites URLs to URLs, URLs to filenames and even + filenames to filenames. 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 + then the API intends for it. +<P> +<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 were translated to filenames (this + has to be this way, because <CODE>.htaccess</CODE> files stay in the + filesystem, so processing has already been reached this stage of + processing). 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 it 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 leads + to a new processing of the API phases from the beginning. + <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. +</OL> + +<P> +Don't forget these two points! + +<H2><A 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 while 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. Just 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 order. And this order is not very obvious. The +rule is this: The rewriting engine loops through the ruleset rule by rule +(<CODE>RewriteRule</CODE> directives!) and when a particular rule matched it +optionally loops through existing corresponding conditions +(<CODE>RewriteCond</CODE> directives). Because of historical reasons the +conditions are given first, the control flow is a little bit 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> -<a name="RewriteEngine"><h3>RewriteEngine</h3></a> -<strong>Syntax:</strong> <code>RewriteEngine</code> {<code>on,off</code>}<br> -<strong>Default:</strong> <strong><code>RewriteEngine off</code></strong><br> -<strong>Context:</strong> server config, virtual host, per-directory config<br> -<p> +<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> matched, 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 exists, it starts an inner loop for processing them in order +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 condition is available. If all conditions matched processing is +continued with the substitution of the URL with <EM>Substitution</EM>. + +<H2><A NAME="InternalBackRefs">Regex Back-Reference Availability</A></H2> + +One important thing here has to be remembered: Whenever you +use parenthesis in <EM>Pattern</EM> or in one of the <EM>CondPattern</EM> +back-reference are internally created which can be used with the +strings <CODE>$N</CODE> and <CODE>%N</CODE> (see below). And these +are available for creating the strings <EM>Substitution</EM> and +<EM>TestCond</EM>. Figure 2 shows at which locations the back-references are +transfered to for expansion. + +<P> +<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> -The <tt>RewriteEngine</tt> 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 <tt>SCRIPT_URx</tt> +<P> +We know, this was a crash course of mod_rewrite's internal processing. But +you will benefit from this knowledge when reading the following documentation +of the available directives. + +<P> +<HR NOSHADE SIZE=1> + +<CENTER> +<H1><A NAME="Configuration">Configuration Directives</A></H1> +</CENTER> + +<P> +<HR NOSHADE SIZE=1> + +<H3><A NAME="RewriteEngine">RewriteEngine</A></H3> +<A + HREF="directive-dict.html#Syntax" + REL="Help" +><STRONG>Syntax:</STRONG></A> + <CODE>RewriteEngine</CODE> {<CODE>on,off</CODE>}<BR> +<A + HREF="directive-dict.html#Default" + REL="Help" +><STRONG>Default:</STRONG></A> + <STRONG><CODE>RewriteEngine off</CODE></STRONG><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 <tt>RewriteRule</tt> directives! - -<p> -<hr noshade size=1> -<p> - -<a name="RewriteOptions"><h3>RewriteOptions</h3></a> -<strong>Syntax:</strong> <code>RewriteOptions</code> <em>Option</em> ...<br> -<strong>Default:</strong> -<em>None</em>-<br> -<strong>Context:</strong> server config, virtual host, per-directory config<br> -<p> - -The <tt>RewriteOption</tt> directive sets some special options for the -current per-server or per-directory configuration. The <em>Option</em> +all <CODE>RewriteRule</CODE> directives! + +<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 you wish to use it in. + +<P> +<HR NOSHADE SIZE=1> +<P> + +<H3><A NAME="RewriteOptions">RewriteOptions</A></H3> +<A + HREF="directive-dict.html#Syntax" + REL="Help" +><STRONG>Syntax:</STRONG></A> <CODE>RewriteOptions</CODE> <EM>Option</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> 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>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: -<ul> -<li>'<strong><code>inherit</code></strong>'<br> +<UL> +<LI>'<STRONG><CODE>inherit</CODE></STRONG>'<BR> 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 gets inherited. In per-directory context this means that conditions and rules of the parent directory's - <tt>.htaccess</tt> configuration gets inherited. -</ul> - -<p> -<hr noshade size=1> -<p> - -<a name="RewriteLog"><h3>RewriteLog</h3></a> -<strong>Syntax:</strong> <code>RewriteLog</code> <em>Filename</em><br> -<strong>Default:</strong> -<em>None</em>-<br> -<strong>Context:</strong> server config, virtual host<br> -<p> - -The <tt>RewriteLog</tt> directive sets the name of the file to which the + <CODE>.htaccess</CODE> configuration gets inherited. +</UL> + +<P> +<HR NOSHADE SIZE=1> +<P> + +<H3><A NAME="RewriteLog">RewriteLog</A></H3> +<A + HREF="directive-dict.html#Syntax" + REL="Help" +><STRONG>Syntax:</STRONG></A> <CODE>RewriteLog</CODE> <EM>Filename</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 ('<tt>/</tt>') then it is assumed to be relative to the -<em>Server Root</em>. The directive should occur only once per server +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="#f0f0f0" cellspacing=0 cellpadding=10> -<tr><td> -To disable the logging of rewriting actions it is not recommended -to set <em>Filename</em> -to <code>/dev/null</code>, because although the rewriting engine does +<P> +<TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10> +<TR><TD> +<STRONG>Notice</STRONG>: To disable the logging of rewriting actions it is +not recommended to set <EM>Filename</EM> +to <CODE>/dev/null</CODE>, because although the rewriting engine does not create output to a logfile it still creates the logfile -output internally. <b>This will slow down the server with no advantage to the -administrator!</b> +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 -<tt>RewriteLog</tt> directive or use <tt>RewriteLogLevel 0</tt>! -</td></tr> -</table> - -<p> -<table width="70%" border=0 bgcolor="#fff0f0" cellspacing=0 cellpadding=10> -<tr><td> -SECURITY: See the <a -href="../misc/security_tips.html">Apache Security -Tips</a> document for details on why your security could be compromised if the +<CODE>RewriteLog</CODE> directive or use <CODE>RewriteLogLevel 0</CODE>! +</TD></TR> +</TABLE> + +<P> +<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> +</TD></TR> +</TABLE> -<p> -<b>Example:</b> -<blockquote> -<pre> +<P> +<STRONG>Example:</STRONG> +<BLOCKQUOTE> +<PRE> RewriteLog "/usr/local/var/apache/logs/rewrite.log" -</pre> -</blockquote> - -<p> -<hr noshade size=1> -<p> - -<a name="RewriteLogLevel"><h3>RewriteLogLevel</h3></a> -<strong>Syntax:</strong> <code>RewriteLogLevel</code> <em>Level</em><br> -<strong>Default:</strong> <strong><code>RewriteLogLevel 0</code></strong><br> -<strong>Context:</strong> server config, virtual host<br> -<p> - -The <tt>RewriteLogLevel</tt> directive set the verbosity level of the rewriting +</PRE> +</BLOCKQUOTE> + +<P> +<HR NOSHADE SIZE=1> +<P> + +<H3><A NAME="RewriteLogLevel">RewriteLogLevel</A></H3> +<A + HREF="directive-dict.html#Syntax" + REL="Help" +><STRONG>Syntax:</STRONG></A> <CODE>RewriteLogLevel</CODE> <EM>Level</EM><BR> +<A + HREF="directive-dict.html#Default" + REL="Help" +><STRONG>Default:</STRONG></A> <STRONG><CODE>RewriteLogLevel 0</CODE></STRONG> +<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 set 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> -To disable the logging of rewriting actions simply set <em>Level</em> to 0. +<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="#f0f0f0" cellspacing=0 cellpadding=10> -<tr><td> -<b>Notice:</b> Using a high value for <i>Level</i> will slow down your Apache +<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 only for debugging or at least -at <em>Level</em> not greater than 2! -</td></tr> -</table> +at <EM>Level</EM> not greater than 2! +</TD></TR> +</TABLE> -<p> -<b>Example:</b> -<blockquote> -<pre> +<P> +<STRONG>Example:</STRONG> +<BLOCKQUOTE> +<PRE> RewriteLogLevel 3 -</pre> -</blockquote> - -<p> -<hr noshade size=1> -<p> - -<a name="RewriteMap"><h3>RewriteMap</h3></a> -<strong>Syntax:</strong> <code>RewriteMap</code> <em>Mapname</em> <code>{txt,dbm,prg}:</code><em>Filename</em><br> -<strong>Default:</strong> not used per default<br> -<strong>Context:</strong> server config, virtual host<br> -<p> - -The <tt>RewriteMap</tt> directive defines an external <em>Rewriting Map</em> +</PRE> +</BLOCKQUOTE> + +<P> +<HR NOSHADE SIZE=1> +<P> + +<H3><A NAME="RewriteLock">RewriteLock</A></H3> +<A + HREF="directive-dict.html#Syntax" + REL="Help" +><STRONG>Syntax:</STRONG></A> <CODE>RewriteLock</CODE> <EM>Filename</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 1.3<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 +SAMP using all other types of rewriting maps. + +<P> +<HR NOSHADE SIZE=1> +<P> + +<H3><A NAME="RewriteMap">RewriteMap</A></H3> +<A + HREF="directive-dict.html#Syntax" + REL="Help" +><STRONG>Syntax:</STRONG></A> <CODE>RewriteMap</CODE> <EM>MapName </EM> + <EM>MapType</EM><CODE>:</CODE><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. -<p> +to insert/substitute fields through a key lookup. The source of this +lookup can be of various types. +<P> -The <a name="mapfunc"><em>Mapname</em></a> is the name of the map and will +The <A 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 - -<blockquote><strong> -<code>${</code> <em>Mapname</em> <code>:</code> <em>LookupKey</em> -<code>|</code> <em>DefaultValue</em> <code>}</code> -</strong></blockquote> - -When such a directive 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 directive is substituted by <em>SubstValue</em>. If -the key is not found then it is substituted by <em>DefaultValue</em>. - -<p> -The <em>Filename</em> must be a valid Unix filepath, containing one -of the following formats: - -<ol> -<li><b>Plain Text Format</b> - <p> - This is a ASCII file which contains either blank lines, comment lines - (starting with a '#' character) or - - <blockquote><strong> - <em>MatchingKey</em> <em>SubstValue</em> - </strong></blockquote> - - pairs - one per line. You can create such files either manually, - using your favorite editor, or by using the programs - <tt>mapcollect</tt> and <tt>mapmerge</tt> from the <tt>support</tt> - directory of the <b>mod_rewrite</b> distribution. - <p> - To declare such a map prefix, <em>Filename</em> with a <code>txt:</code> - string as in the following example: - -<p> -<table border=0 cellspacing=1 cellpadding=5 bgcolor="#f0f0f0"> -<tr><td><pre> -# -# map.real-to-user -- maps realnames to usernames -# +rewriting rule via one of the following constructs: + +<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 +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: + +<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. + + <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 -Dr.Fred.Klabuster fred # Mr. DAU -</pre></td></tr> -</table> - -<p> -<table border=0 cellspacing=1 cellpadding=5 bgcolor="#f0f0f0"> -<tr><td><pre> -RewriteMap real-to-host txt:/path/to/file/map.real-to-user -</pre></td></tr> -</table> - -<p> -<li><b>DBM Hashfile Format</b> - <p> - This is a binary NDBM format file containing the - same contents as the <em>Plain Text Format</em> files. You can create - such a file with any NDBM tool or with the <tt>dbmmanage</tt> program - from the <tt>support</tt> directory of the Apache distribution. - <p> - To declare such a map prefix <em>Filename</em> with a <code>dbm:</code> - string. -<p> -<li><b>Program Format</b> - <p> - This is a Unix executable, not a lookup file. To create it you can use +Mr.Joe.Average joe # Mr. Average +</PRE></TD></TR> +</TABLE> + +<P> +<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> + +<P> +<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''. 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> + +<P> +<TABLE BORDER=0 CELLSPACING=1 CELLPADDING=5 BGCOLOR="#F0F0F0"> +<TR><TD><PRE> +RewriteMap servers rnd:/path/to/file/map.txt +</PRE></TD></TR> +</TABLE> + +<P> +<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 +## + +($txtmap, $dbmmap) = @ARGV; +open(TXT, "<$txtmap"); +dbmopen(%DB, $dbmmap, 0644); +while (<TXT>) { + next if (m|^s*#.*| or m|^s*$|); + $DB{$1} = $2 if (m|^\s*(\S+)\s+(\S+)$|); +} +dbmclose(%DB); +close(TXT)</PRE></TD></TR> + </TABLE> + <P> + <TABLE BORDER=0 CELLSPACING=1 CELLPADDING=5 BGCOLOR="#F0F0F0"> + <TR><TD><PRE>$ txt2dbm map.txt map.db </PRE></TD></TR> + </TABLE> +<P> +<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: + <UL> + <LI><STRONG>toupper</STRONG>:<BR> + Converts the looked up key to all upper case. + <LI><STRONG>tolower</STRONG>:<BR> + Converts the looked up key to all lower case. + <LI><STRONG>escape</STRONG>:<BR> + Translates special characters in the looked up key to hex-encodings. + <LI><STRONG>unescape</STRONG>:<BR> + Translates hex-encodings in the looked up key back to special characters. + </UL> +<P> +<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 Unix program, not a map file. To create it you can use the language of your choice, but the result has to be a run-able Unix - binary (i.e. either object-code or a script with the - magic cookie trick '<tt>#!/path/to/interpreter</tt>' as the first line). - <p> + 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> This program gets started once at startup of the Apache servers and then - communicates with the rewriting engine over its <tt>stdin</tt> and - <tt>stdout</tt> file-handles. For each map-function lookup it will + 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 - <tt>stdin</tt>. It then has to give back the looked-up value as a - newline-terminated string on <tt>stdout</tt> or the four-character string - ``<tt>NULL</tt>'' if it fails (i.e. there is no corresponding value + <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 - (i.e. key == value) could be: - <p> -<table border=0 cellspacing=1 cellpadding=5 bgcolor="#f0f0f0"> -<tr><td><pre> + (<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>) { @@ -321,90 +793,117 @@ while (<STDIN>) { # or lookups should occur... print $_; } -</pre></td></tr> -</table> - <p> - <b>But be very careful:</b><br> - <ol> - <li>``<i>Keep the program simple, stupid</i>'' (KISS), because +</PRE></TD></TR> +</TABLE> + <P> + But be very careful:<BR> + <OL> + <LI>``<EM>Keep the program simple, stupid</EM>'' (KISS), because if this program hangs it will lead to a hang of the Apache server when the rule occurs. - <li>Avoid one common mistake: never do buffered I/O on <tt>stdout</tt>! - This will cause a deadloop! Hence the ``<tt>$|=1</tt>'' in the above - example... - </ol> - <p> - To declare such a map prefix <em>Filename</em> with a <code>prg:</code> - string. -</ol> - -The <tt>RewriteMap</tt> directive can occur more than once. For each -mapping-function use one <tt>RewriteMap</tt> directive to declare its -rewriting mapfile. While you cannot <b>declare</b> a map in per-directory -context it is of course possible to <b>use</b> this map in per-directory -context. - -<p> -<table width="70%" border=0 bgcolor="#f0f0f0" cellspacing=0 cellpadding=10> -<tr><td> -For plain text and DBM format files the looked-up keys are cached in-core -until the <tt>mtime</tt> of the mapfile changes or the server does a + <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>Use the <SAMP>RewriteLock</SAMP> directive to define a lockfile + mod_rewrite can use to synchronize the communication to the program. + Per default no such synchronization takes place. + </OL> +</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. + +<P> +<TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10> +<TR><TD> +<STRONG>Notice:</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 <b>every</b> request. This is no problem, because the external lookup -only happens once! -</td></tr> -</table> - - -<p> -<hr noshade size=1> -<p> - -<a name="RewriteBase"><h3>RewriteBase</h3></a> -<strong>Syntax:</strong> <code>RewriteBase</code> <em>BaseURL</em><br> -<strong>Default:</strong> <em>default is the physical directory path</em><br> -<strong>Context:</strong> per-directory config<br> -<p> - -The <tt>RewriteBase</tt> directive explicitly sets the base URL for -per-directory rewrites. As you will see below, <tt>RewriteRule</tt> can be -used in per-directory config files (<tt>.htaccess</tt>). There it will act -locally, i.e. the local directory prefix is stripped at this stage of +for <STRONG>every</STRONG> request. This is no problem, because the +external lookup only happens once! +</TD></TR> +</TABLE> + +<P> +<HR NOSHADE SIZE=1> +<P> + +<H3><A NAME="RewriteBase">RewriteBase</A></H3> +<A + HREF="directive-dict.html#Syntax" + REL="Help" +><STRONG>Syntax:</STRONG></A> <CODE>RewriteBase</CODE> <EM>BaseURL</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. -<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. <b>But at most websites URLs are -<b>NOT</b> directly related to physical filename paths, so this assumption -will be usually be wrong!</b> There you have to use the <tt>RewriteBase</tt> -directive to specify the correct URL-prefix. - -<p> -<table width="70%" border=0 bgcolor="#fff0f0" cellspacing=0 cellpadding=10> -<tr><td> -So, if your webserver's URLs are <b>not</b> directly -related to physical file paths, you have to use <tt>RewriteBase</tt> in every -<tt>.htaccess</tt> files where you want to use <tt>RewriteRule</tt> +<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 +<STRONG>NOT</STRONG> directly related to physical filename paths, so this +assumption will be 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> +</TD></TR> +</TABLE> -<p> -<b>Example:</b> +<P> +<STRONG>Example:</STRONG> -<blockquote> +<BLOCKQUOTE> Assume the following per-directory config file: -<p> -<table border=0 cellspacing=1 cellpadding=5 bgcolor="#f0f0f0"> -<tr><td><pre> +<P> +<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, i.e. the server -# has a 'Alias /xyz /abc/def' directive e.g. +# 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 @@ -415,35 +914,36 @@ RewriteBase /xyz # now the rewriting rules RewriteRule ^oldstuff\.html$ newstuff.html -</pre></td></tr> -</table> - -<p> -In the above example, a request to <tt>/xyz/oldstuff.html</tt> gets correctly -rewritten to the physical file <tt>/abc/def/newstuff.html</tt>. - -<p> -<table width="70%" border=0 bgcolor="#fff0f0" cellspacing=0 cellpadding=10> -<tr><td> -<font size=-1> -<b>For the Apache hackers:</b><br> +</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>Notice - For the Apache hackers:</STRONG><BR> The following list gives detailed information about the internal processing steps: -<p> -<pre> +<P> +<PRE> Request: /xyz/oldstuff.html Internal Processing: - /xyz/oldstuff.html -> /abc/def/oldstuff.html (per-server Alias) - /abc/def/oldstuff.html -> /abc/def/newstuff.html (per-dir RewriteRule) - /abc/def/newstuff.html -> /xyz/newstuff.html (per-dir RewriteBase) - /xyz/newstuff.html -> /abc/def/newstuff.html (per-server Alias) + /xyz/oldstuff.html -> /abc/def/oldstuff.html (per-server Alias) + /abc/def/oldstuff.html -> /abc/def/newstuff.html (per-dir RewriteRule) + /abc/def/newstuff.html -> /xyz/newstuff.html (per-dir RewriteBase) + /xyz/newstuff.html -> /abc/def/newstuff.html (per-server Alias) Result: /abc/def/newstuff.html -</pre> +</PRE> This seems very complicated but is the correct Apache internal processing, because the per-directory rewriting comes too late in the process. So, @@ -452,263 +952,343 @@ kernel! BUT: While this seems like a serious overhead, it really isn't, because this re-injection happens fully internal 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> +</FONT> +</TD></TR> +</TABLE> + +</BLOCKQUOTE> + + +<P> +<HR NOSHADE SIZE=1> +<P> + +<H3><A NAME="RewriteCond">RewriteCond</A></H3> +<A + HREF="directive-dict.html#Syntax" + REL="Help" +><STRONG>Syntax:</STRONG></A> <CODE>RewriteCond</CODE> <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. -</blockquote> +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> +<EM>TestString</EM> is a string which can contains the following +expanded constructs in addition to plain text: -<p> -<hr noshade size=1> -<p> +<UL> +<LI><STRONG>RewriteRule backreferences</STRONG>: These are backreferences of + the form -<a name="RewriteCond"><h3>RewriteCond</h3></a> -<strong>Syntax:</strong> <code>RewriteCond</code> <em>TestString</em> <em>CondPattern</em><br> -<strong>Default:</strong> -<em>None</em>-<br> -<strong>Context:</strong> server config, virtual host, per-directory config<br> -<p> +<BLOCKQUOTE><STRONG> +<CODE>$N</CODE> +</STRONG></BLOCKQUOTE> -The <tt>RewriteCond</tt> directive defines a rule condition. Precede a -<tt>RewriteRule</tt> directive with one or more <tt>RewriteCond</tt> -directives. +(1 <= 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). -The following rewriting rule is only used if its pattern matches the current -state of the URI <b>AND</b> if these additional conditions apply, too. +<P> +<LI><STRONG>RewriteCond backreferences</STRONG>: These are backreferences of +the form + +<BLOCKQUOTE><STRONG> +<CODE>%N</CODE> +</STRONG></BLOCKQUOTE> -<p> -<em>TestString</em> is a string which contains server-variables of the form +(1 <= N <= 9) which provide access to the grouped parts (parenthesis!) of +the pattern from the last matched <CODE>RewriteCond</CODE> directive in the +current bunch of conditions. -<blockquote><strong> -<tt>%{</tt> <em>NAME_OF_VARIABLE</em> <tt>}</tt> -</strong></blockquote> +<P> +<LI><STRONG>Server-Variables</STRONG>: These are variables + of the form -where <em>NAME_OF_VARIABLE</em> can be a string +<BLOCKQUOTE><STRONG> +<CODE>%{</CODE> <EM>NAME_OF_VARIABLE</EM> <CODE>}</CODE> +</STRONG></BLOCKQUOTE> + +where <EM>NAME_OF_VARIABLE</EM> can be a string of the following list: -<p> -<table bgcolor="#f0f0f0" cellspacing=0 cellpadding=5> -<tr> -<td valign=top> -<b>HTTP headers:</b><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> -</td> - -<td valign=top> -<b>connection & request:</b><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> -</td> - -</tr> -<tr> - -<td valign=top> -<b>server internals:</b><p> -<font size=-1> -DOCUMENT_ROOT<br> -SERVER_ADMIN<br> -SERVER_NAME<br> -SERVER_PORT<br> -SERVER_PROTOCOL<br> -SERVER_SOFTWARE<br> -SERVER_VERSION<br> -</font> -</td> - -<td valign=top> -<b>system stuff:</b><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> -</td> - -<td valign=top> -<b>specials:</b><p> -<font size=-1> -API_VERSION<br> -THE_REQUEST<br> -REQUEST_URI<br> -REQUEST_FILENAME<br> -IS_SUBREQ<br> -</font> -</td> -</tr> -</table> - - -<p> -<table width="70%" border=0 bgcolor="#f0f0f0" cellspacing=0 cellpadding=10> -<tr><td> -These variables all correspond to the similar named HTTP MIME-headers, C -variables of the Apache server or <tt>struct tm</tt> fields of the Unix -system. -</td></tr> -</table> - -<p> +<P> +<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> +</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> +</TD> + +</TR> +<TR> + +<TD VALIGN=TOP> +<STRONG>server internals:</STRONG><P> +<FONT SIZE=-1> +DOCUMENT_ROOT<BR> +SERVER_ADMIN<BR> +SERVER_NAME<BR> +SERVER_PORT<BR> +SERVER_PROTOCOL<BR> +SERVER_SOFTWARE<BR> +</FONT> +</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> +</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> +</TD> +</TR> +</TABLE> + +<P> +<TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10> +<TR><TD> +<STRONG>Notice:</STRONG> These variables all correspond to the similar named +HTTP MIME-headers, C variables of the Apache server or <CODE>struct tm</CODE> +fields of the Unix system. +</TD></TR> +</TABLE> + +</UL> + +<P> Special Notes: -<ol> -<li>The variables SCRIPT_FILENAME and REQUEST_FILENAME contain the same -value, i.e. the value of the <tt>filename</tt> field of the internal -<tt>request_rec</tt> structure of the Apache server. The first name is just the + +<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 <tt>uri</tt> -field of <tt>request_rec</tt>). - -<p> -<li>There is the special format: <tt>%{ENV:variable}</tt> where -<i>variable</i> can be any environment variable. This is looked-up via -internal Apache structures and (if not found there) via <tt>getenv()</tt> from -the Apache server process. - -<p> -<li>There is the special format: <tt>%{HTTP:header}</tt> where -<i>header</i> can be any HTTP MIME-header name. This is looked-up -from the HTTP request. Example: <tt>%{HTTP:Proxy-Connection}</tt> -is the value of the HTTP header ``<tt>Proxy-Connection:</tt>''. - -<p> -<li>There is the special format: <tt>%{LA-U:url}</tt> -for look-aheads like <tt>-U</tt>. This performs a internal sub-request to -look-ahead for the final value of <i>url</i>. - -<p> -<li>There is the special format: <tt>%{LA-F:file}</tt> -for look-aheads like <tt>-F</tt>. This performs a internal sub-request to -look-ahead for the final value of <i>file</i>. -</ol> - -<p> -<em>CondPattern</em> is the condition pattern, i.e. a regular expression -which gets applied to the current instance of the <em>TestString</em>, i.e. -<em>TestString</em> gets evaluated and then matched against -<em>CondPattern</em>. - -<p> -<b>Remember:</b> <em>CondPattern</em> is a standard -<em>Extended Regular Expression</em> with some additions: - -<ol> -<li>You can precede the pattern string with a '<tt>!</tt>' character -(exclamation mark) to specify a <b>non</b>-matching pattern. - -<p> -<li> -There are some special variants of <em>CondPatterns</em>. Instead of real +counterpart to REQUEST_URI (which contains the value of the <CODE>uri</CODE> +field of <CODE>request_rec</CODE>). + +<P> +<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. + +<P> +<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>''. + +<P> +<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 actually is 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. + +<P> +<LI>There is the special format: <CODE>%{LA-F:variable}</CODE> which perform an +internal (filename-based) sub-request to determine the final value of +<EM>variable</EM>. This is the most of the time the same as LA-U above. +</OL> + +<P> +<EM>CondPattern</EM> is the condition pattern, <EM>i.e.</EM>, a regular +expression +which gets applied to the current instance of the <EM>TestString</EM>, +<EM>i.e.</EM>, <EM>TestString</EM> gets evaluated and then matched against +<EM>CondPattern</EM>. + +<P> +<STRONG>Remember:</STRONG> <EM>CondPattern</EM> is a standard +<EM>Extended Regular Expression</EM> with some additions: + +<OL> +<LI>You can precede the pattern string with a '<CODE>!</CODE>' character +(exclamation mark) to specify a <STRONG>non</STRONG>-matching pattern. + +<P> +<LI> +There are some special variants of <EM>CondPatterns</EM>. Instead of real regular expression strings you can also use one of the following: -<p> -<ul> -<li>'<b><CondPattern</b>' (is lexicographically lower)<br> -Treats the <i>CondPattern</i> as a plain string and compares it -lexicographically to <i>TestString</i> and results in a true expression if -<i>TestString</i> is lexicographically lower then <i>CondPattern</i>. -<p> -<li>'<b>>CondPattern</b>' (is lexicographically greater)<br> -Treats the <i>CondPattern</i> as a plain string and compares it -lexicographically to <i>TestString</i> and results in a true expression if -<i>TestString</i> is lexicographically greater then <i>CondPattern</i>. -<p> -<li>'<b>=CondPattern</b>' (is lexicographically equal)<br> -Treats the <i>CondPattern</i> as a plain string and compares it -lexicographically to <i>TestString</i> and results in a true expression if -<i>TestString</i> is lexicographically equal to <i>CondPattern</i>, i.e the +<P> +<UL> +<LI>'<STRONG><CondPattern</STRONG>' (is lexicographically lower)<BR> +Treats the <EM>CondPattern</EM> as a plain string and compares it +lexicographically to <EM>TestString</EM> and results in a true expression if +<EM>TestString</EM> is lexicographically lower than <EM>CondPattern</EM>. +<P> +<LI>'<STRONG>>CondPattern</STRONG>' (is lexicographically greater)<BR> +Treats the <EM>CondPattern</EM> as a plain string and compares it +lexicographically to <EM>TestString</EM> and results in a true expression if +<EM>TestString</EM> is lexicographically greater than <EM>CondPattern</EM>. +<P> +<LI>'<STRONG>=CondPattern</STRONG>' (is lexicographically equal)<BR> +Treats the <EM>CondPattern</EM> as a plain string and compares it +lexicographically to <EM>TestString</EM> and results in a true expression if +<EM>TestString</EM> is lexicographically equal to <EM>CondPattern</EM>, i.e the two strings are exactly equal (character by character). -<p> -<li>'<b>-d</b>' (is <b>d</b>irectory)<br> -Treats the <i>TestString</i> as a pathname and +If <EM>CondPattern</EM> is just <SAMP>""</SAMP> (two quotation marks) this +compares <EM>TestString</EM> against the empty string. +<P> +<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. -<p> -<li>'<b>-f</b>' (is regular <b>f</b>ile)<br> -Treats the <i>TestString</i> as a pathname and +<P> +<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. -<p> -<li>'<b>-s</b>' (is regular file with <b>s</b>ize)<br> -Treats the <i>TestString</i> as a pathname and -tests if it exists and is a regular file with size greater then zero. -<p> -<li>'<b>-l</b>' (is symbolic <b>l</b>ink)<br> -Treats the <i>TestString</i> as a pathname and +<P> +<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. +<P> +<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. -<p> -<li>'<b>-F</b>' (is existing file via subrequest)<br> -Checks if <i>TestString</i> is a valid file and accessible via all the +<P> +<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! -<p> -<li>'<b>-U</b>' (is existing URL via subrequest)<br> -Checks if <i>TestString</i> is a valid URL and accessible via all the server's +<P> +<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 servers performance! -</ul> -<p> -Notice: All of these tests can also be prefixed by a not ('!') character +your server's performance! +</UL> +<P> +<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 a not ('!') character to negate their meaning. -</ol> +</TD></TR> +</TABLE> +</OL> -<p> -Additionally you can set special flags for <em>CondPattern</em> by appending +<P> +Additionally you can set special flags for <EM>CondPattern</EM> by appending -<blockquote><strong> -<code>[</code><em>flags</em><code>]</code> -</strong></blockquote> +<BLOCKQUOTE><STRONG> +<CODE>[</CODE><EM>flags</EM><CODE>]</CODE> +</STRONG></BLOCKQUOTE> -as the third argument to the <tt>RewriteCond</tt> directive. <em>Flags</em> +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>' (<b>n</b>o <b>c</b>ase)<br> - This makes the condition test case-insensitive, i.e. there is +<UL> +<LI>'<STRONG><CODE>nocase|NC</CODE></STRONG>' (<STRONG>n</STRONG>o <STRONG>c</STRONG>ase)<BR> + This makes the condition 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>. -<p> -<li>'<strong><code>ornext|OR</code></strong>' (<b>or</b> next condition)<br> + <EM>TestString</EM> and the <EM>CondPattern</EM>. +<P> +<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: - <p> -<blockquote><pre> + <P> +<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> +</PRE></BLOCKQUOTE> Without this flag you had to write down the cond/rule three times. -</ul> +</UL> -<p> -<b>Example:</b> -<blockquote> +<P> +<STRONG>Example:</STRONG> +<BLOCKQUOTE> -To rewrite the Homepage of a site according to the ``<tt>User-Agent:</tt>'' +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> +<BLOCKQUOTE><PRE> RewriteCond %{HTTP_USER_AGENT} ^Mozilla.* RewriteRule ^/$ /homepage.max.html [L] @@ -716,354 +1296,417 @@ RewriteCond %{HTTP_USER_AGENT} ^Lynx.* RewriteRule ^/$ /homepage.min.html [L] RewriteRule ^/$ /homepage.std.html [L] -</pre></blockquote> +</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, etc. If you use the Lynx browser (which is Terminal-based), then you -get the min homepage, which contains no images, no tables, etc. If you +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> - -<p> -<hr noshade size=1> -<p> - -<a name="RewriteRule"><h3>RewriteRule</h3></a> -<strong>Syntax:</strong> <code>RewriteRule</code> <em>Pattern</em> <em>Substitution</em><br> -<strong>Default:</strong> -<em>None</em>-<br> -<strong>Context:</strong> server config, virtual host, per-directory config<br> - -<p> -The <tt>RewriteRule</tt> directive is the real rewriting workhorse. The +</BLOCKQUOTE> + +<P> +<HR NOSHADE SIZE=1> +<P> + +<H3><A NAME="RewriteRule">RewriteRule</A></H3> +<A + HREF="directive-dict.html#Syntax" + REL="Help" +><STRONG>Syntax:</STRONG></A> <CODE>RewriteRule</CODE> <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 <b>definition order</b> of these rules is -<b>important</b>, because this order is used when applying the rules at +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> -<a name="patterns"><em>Pattern</em></a> can be (for Apache 1.1.x a System -V8 and for Apache 1.2.x a POSIX) <a name="regexp">regular expression</a> +<P> +<A NAME="patterns"><EM>Pattern</EM></A> can be (for Apache 1.1.x a System +V8 and for Apache 1.2.x a POSIX) <A 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 original requested URL, because there could be any number of rules before which already 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><code>^</code></strong> Start of line -<strong><code>$</code></strong> End of line -<strong><code>.</code></strong> Any single character -<strong><code>[</code></strong>chars<strong><code>]</code></strong> One of chars -<strong><code>[^</code></strong>chars<strong><code>]</code></strong> None of chars - -<strong><code>?</code></strong> 0 or 1 of the preceding char -<strong><code>*</code></strong> 0 or N of the preceding char -<strong><code>+</code></strong> 1 or N of the preceding char - -<strong><code>\</code></strong>char escape that specific char - (e.g. for specifying the chars "<code>.[]()</code>" etc.) - -<strong><code>(</code></strong>string<strong><code>)</code></strong> Grouping of chars (the <b>N</b>th group can be used on the RHS with <code>$</code><b>N</b>) -</pre> -</td> -</tr> -</table> - -<p> -Additionally the NOT character ('<tt>!</tt>') is a possible pattern -prefix. This gives you the ability to negate a pattern; to say, for instance: ``<i>if -the current URL does <b>NOT</b> match to this pattern</i>''. This can be used -for special cases where it is better to match the negative pattern or as a -last default rule. - -<p> -<table width="70%" border=0 bgcolor="#fff0f0" cellspacing=0 cellpadding=10> -<tr><td> -<b>Notice!</b> When using the NOT character to negate a pattern you cannot +<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 > 1) + <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. When you are interested in more detailed and deeper +information about regular expressions and its variants (POSIX regex, Perl +regex, <EM>etc.</EM>) have a look at the following dedicated book on this topic: + +<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 to this +pattern</EM>''. This can be used for special cases where it is better 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 <tt>$N</tt> in the +consequence, if negated patterns are used, you cannot use <CODE>$N</CODE> in the substitution string! -</td></tr> -</table> +</TD></TR> +</TABLE> -<p> -<a name="rhs"><em>Substitution</em></a> of a rewriting rule is the string +<P> +<A 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 - -<ol> -<li>pattern-group back-references (<code>$N</code>) -<li>server-variables as in rule condition test-strings (<code>%{VARNAME}</code>) -<li><a href="#mapfunc">mapping-function</a> calls (<code>${mapname:key|default}</code>) -</ol> - -Back-references are <code>$</code><b>N</b> (<b>N</b>=1..9) identifiers which -will be replaced by the contents of the <b>N</b>th group of the matched -<em>Pattern</em>. The server-variables are the same as for the -<em>TestString</em> of a <tt>RewriteCond</tt> directive. The -mapping-functions come from the <tt>RewriteMap</tt> directive and are +<EM>Pattern</EM> matched. Beside plain text you can use + +<OL> +<LI>back-references <CODE>$N</CODE> to the RewriteRule pattern +<LI>back-references <CODE>%N</CODE> to the last matched RewriteCond pattern +<LI>server-variables as in rule condition test-strings (<CODE>%{VARNAME}</CODE>) +<LI><A HREF="#mapfunc">mapping-function</A> calls (<CODE>${mapname:key|default}</CODE>) +</OL> + +Back-references are <CODE>$</CODE><STRONG>N</STRONG> (<STRONG>N</STRONG>=1..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> +<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 <b>completely replaced</b> by the <em>Substitution</em> and 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><b>L</b></code> flag - see below). +terminated by a <CODE><STRONG>L</STRONG></CODE> flag - see below). -<p> -There is a special substitution string named '<tt>-</tt>' which means: -<b>NO substitution</b>! Sounds silly? No, it is useful to provide rewriting -rules which <b>only</b> match some URLs but do no substitution, e.g. in -conjunction with the <b>C</b> (chain) flag to be able to have more than one +<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="#fff0f0" cellspacing=0 cellpadding=10> -<tr><td> -<b>Notice</b>: There is a special feature. When you prefix a substitution -field with <tt>http://</tt><em>thishost</em>[<em>:thisport</em>] then -<b>mod_rewrite</b> automatically strips it out. This auto-reduction on +<P> +<TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10> +<TR><TD> +<STRONG>Notice</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. -<p> -<b>Remember:</b> An unconditional external redirect to your own server will -not work with the prefix <tt>http://thishost</tt> because of this feature. -To achieve such a self-redirect, you have to use the <b>R</b>-flag (see +</TD></TR> +</TABLE> + +<P> +<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> +</TD></TR> +</TABLE> -<p> -Additionally you can set special flags for <em>Substitution</em> by appending +<P> +Additionally you can set special flags for <EM>Substitution</EM> by appending -<blockquote><strong> -<code>[</code><em>flags</em><code>]</code> -</strong></blockquote> +<BLOCKQUOTE><STRONG> +<CODE>[</CODE><EM>flags</EM><CODE>]</CODE> +</STRONG></BLOCKQUOTE> -as the third argument to the <tt>RewriteRule</tt> directive. <em>Flags</em> is a +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>[=<i>code</i>]</strong>' (force <a name="redirect"><b>r</b>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 <i>code</i> is given a HTTP response +<UL> +<LI>'<STRONG><CODE>redirect|R</CODE> [=<EM>code</EM>]</STRONG>' (force <A 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: <tt>temp</tt> (default), <tt>permanent</tt>, - <tt>seeother</tt>. + 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 gives it back to the client, e.g. translate - ``<code>/~</code>'' into ``<code>/u/</code>'' or always append a slash to - <code>/u/</code><em>user</em>, etc.<br> - <p> - <b>Notice:</b> When you use this flag, make sure that the + canonicalize the URL and gives 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>Notice:</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>, but rewriting goes on. + URL with <CODE>http://thishost[:thisport]/</CODE>, but rewriting goes on. 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>'<strong><code>forbidden|F</code></strong>' (force URL to be <b>f</b>orbidden)<br> - This forces the current URL to be forbidden, i.e. it immediately sends +<P> +<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. -<p> -<li>'<strong><code>gone|G</code></strong>' (force URL to be <b>g</b>one)<br> - This forces the current URL to be gone, i.e. it immediately sends back a +<P> +<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 no longer existing pages as gone. -<p> -<li>'<strong><code>proxy|P</code></strong>' (force <b>p</b>roxy)<br> +<P> +<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 (i.e. rewriting rule processing stops here) put - through the proxy module. You have to make sure that the substitution - string is a valid URI (e.g. typically <tt>http://</tt>) 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 <tt>mod_proxy</tt> directive <tt>ProxyPass</tt>, to map - some remote stuff into the namespace of the local server. - <p> - Notice: <b>You really have to put <tt>ProxyRequests On</tt> into your - server configuration to prevent proxy requests from leading to core-dumps - inside the Apache kernel. If you have not compiled in the proxy module, - then there is no core-dump problem, because mod_rewrite checks for - existence of the proxy module and if lost forbids proxy URLs. </b> -<p> -<li>'<strong><code>last|L</code></strong>' (<b>l</b>ast rule)<br> + 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>'<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 + <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 which may be wrong. For - example, use it to rewrite the root-path URL ('<code>/</code>') to a real - one, e.g. '<code>/e/www/</code>'. -<p> -<li>'<strong><code>next|N</code></strong>' (<b>n</b>ext round)<br> + example, use it to rewrite the root-path URL ('<CODE>/</CODE>') to a real + one, <EM>e.g.</EM>, '<CODE>/e/www/</CODE>'. +<P> +<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, i.e. to - immediately go to the top of the loop. <br> - <b>But be careful not to create a deadloop!</b> -<p> -<li>'<strong><code>chain|C</code></strong>' (<b>c</b>hained with next rule)<br> + <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 a deadloop!</STRONG> +<P> +<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 - also be chained with its following rule, etc.). This has the following - effect: if a rule matches, then processing continues as usual, i.e. the - flag has no effect. If the rule does <b>not</b> match, then all following + also be chained with its 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 - ``<tt>.www</tt>'' part inside a per-directory rule set when you let an - external redirect happen (where the ``<tt>.www</tt>'' part should not to + ``<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!). -<p> -<li>'<strong><code>type|T</code></strong>=<em>mime-type</em>' (force MIME <b>t</b>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 old <tt>mod_alias</tt> - directive <tt>ScriptAlias</tt> which internally forces all files inside +<P> +<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 - ``<tt>application/x-httpd-cgi</tt>''. -<p> -<li>'<strong><code>nosubreq|NS</code></strong>' (used only if <b>n</b>o internal <b>s</b>ub-request)<br> + ``<CODE>application/x-httpd-cgi</CODE>''. +<P> +<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 <tt>mod_include</tt> tries to find out - information about possible directory default files (<tt>index.xxx</tt>). + 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> + 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>'<strong><code>qsappend|QSA</code></strong>' (<b>q</b>uery <b>s</b>tring - <b>a</b>ppend)<br> +<P> +<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. +<P> +<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. -<p> -<li>'<strong><code>passthrough|PT</code></strong>' (<b>p</b>ass <b>t</b>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 <tt>RewriteRule</tt> directives by - <tt>Alias</tt>, <tt>ScriptAlias</tt>, <tt>Redirect</tt>, etc. directives +<P> +<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 <tt>/abc</tt> to <tt>/def</tt> via the rewriting - engine of <tt>mod_rewrite</tt> and then <tt>/def</tt> to <tt>/ghi</tt> - with <tt>mod_alias</tt>: - <pre> + 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 <tt>PT</tt> flag then <tt>mod_rewrite</tt> - will do its job fine, i.e. it rewrites <tt>uri=/abc/...</tt> to - <tt>filename=/def/...</tt> as a full API-compliant URI-to-filename - translator should do. Then <tt>mod_alias</tt> comes and tries to do a + </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> - Notice: <b>You have to use this flag if you want to intermix directives - of different modules which contain URL-to-filename translators</b>. The - typical example is the use of <tt>mod_alias</tt> and - <tt>mod_rewrite</tt>.. -<p> -<table width="70%" border=0 bgcolor="#fff0f0" cellspacing=0 cellpadding=10> -<tr><td> + <P> + Notice: <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> - <b>For the Apache hackers:</b><br> + <STRONG>Notice - For the 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 hooks into Apache version 2.0. -</font> -</td></tr> -</table> -<p> -<li>'<strong><code>skip|S</code></strong>=<em>num</em>' (<b>s</b>kip next rule(s))<br> - This flag forces the rewriting engine to skip the next <em>num</em> rules +</FONT> +</TD></TR> +</TABLE> +<P> +<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 - a <tt>skip=N</tt> where N is the number of rules in the else-clause. - (This is <b>not</b> the same as the 'chain|C' flag!) -<p> -<li>'<strong><code>env|E=</code></strong><i>VAR</i>:<i>VAL</i>' (set <b>e</b>nvironment variable)<br> - This forces an environment variable named <i>VAR</i> to be set to the value - <i>VAL</i>, where <i>VAL</i> can contain regexp backreferences <tt>$N</tt> - which will be expanded. You can use this flag more than once to set more - than one variable. The variables can be later dereferenced at a lot of - situations, but the usual location will be from within XSSI (via - <tt><!--#echo var="VAR"--></tt>) or CGI (e.g. <tt>$ENV{'VAR'}</tt>). - But additionally you can also dereference it in a following RewriteCond - pattern via <tt>%{ENV:VAR}</tt>. Use this to strip but remember - information from URLs. -</ul> - -<p> -<table width="70%" border=0 bgcolor="#fff0f0" cellspacing=0 cellpadding=10> -<tr><td> -Remember: Never forget that <em>Pattern</em> gets applied to a complete URL -in per-server configuration files. <b>But in per-directory configuration + a <CODE>skip=N</CODE> where N is the number of rules in the else-clause. + (This is <STRONG>not</STRONG> the same as the 'chain|C' flag!) +<P> +<LI>'<STRONG><CODE>env|E=</CODE></STRONG><EM>VAR</EM>:<EM>VAL</EM>' (set <STRONG>e</STRONG>nvironment variable)<BR> + This forces an environment variable named <EM>VAR</EM> to be set to the + value <EM>VAL</EM>, where <EM>VAL</EM> can contain regexp backreferences + <CODE>$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 at a lot of situations, but the usual location will be from + within XSSI (via <CODE><!--#echo var="VAR"--></CODE>) or CGI (<EM>e.g.</EM> + <CODE>$ENV{'VAR'}</CODE>). But additionally you can also dereference it in a + following RewriteCond pattern via <CODE>%{ENV:VAR}</CODE>. Use this to strip + but remember information from URLs. +</UL> + +<P> +<TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10> +<TR><TD> +<STRONG>Notice:</STRONG> Never forget that <EM>Pattern</EM> gets 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!) gets automatically <em>removed</em> for the pattern matching and -automatically <em>added</em> after the substitution has been done.</b> This feature is +directory!) gets 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> +<P> There is one exception: If a substitution string starts with -``<tt>http://</tt>'' then the directory prefix will be <b>not</b> added and a -external redirect or proxy throughput (if flag <b>P</b> is used!) is forced! -</td></tr> -</table> - -<p> -<table width="70%" border=0 bgcolor="#fff0f0" cellspacing=0 cellpadding=10> -<tr><td> -Notice! To enable the rewriting engine for per-directory configuration files -you need to set ``<tt>RewriteEngine On</tt>'' in these files <b>and</b> -``<tt>Option FollowSymLinks</tt>'' enabled. If your administrator has -disabled override of <tt>FollowSymLinks</tt> for a user's directory, then +``<CODE>http://</CODE>'' then the directory prefix will be <STRONG>not</STRONG> added and a +external redirect or proxy throughput (if flag <STRONG>P</STRONG> is used!) is forced! +</TD></TR> +</TABLE> + +<P> +<TABLE WIDTH="70%" BORDER=0 BGCOLOR="#E0E0F0" CELLSPACING=0 CELLPADDING=10> +<TR><TD> +<STRONG>Notice:</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>Option FollowSymLinks</CODE>'' 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> +</TD></TR> +</TABLE> -<p> +<P> Here are all possible substitution combinations and their meanings: -<p> -<b>Inside per-server configuration (<tt>httpd.conf</tt>)<br> -for request ``<tt>GET /somepath/pathinfo</tt>'':</b><br> +<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> -<b>Given Rule</b> <b>Resulting Substitution</b> +<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! @@ -1094,23 +1737,23 @@ for request ``<tt>GET /somepath/pathinfo</tt>'':</b><br> ^/somepath(.*) http://otherhost/otherpath$1 [P] http://otherhost/otherpath/pathinfo via internal proxy -</pre> -</td> -</tr> -</table> - -<p> -<b>Inside per-directory configuration for <tt>/somepath</tt><br> -(i.e. file <tt>.htaccess</tt> in dir <tt>/physical/path/to/somepath</tt> containing -<tt>RewriteBase /somepath</tt>)<br> for -request ``<tt>GET /somepath/localpath/pathinfo</tt>'':</b><br> - -<p> -<table bgcolor="#f0f0f0" cellspacing=0 cellpadding=5> -<tr> -<td> -<pre> -<b>Given Rule</b> <b>Resulting Substitution</b> +</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 @@ -1142,90 +1785,103 @@ request ``<tt>GET /somepath/localpath/pathinfo</tt>'':</b><br> ^localpath(.*) http://otherhost/otherpath$1 [P] http://otherhost/otherpath/pathinfo via internal proxy -</pre> -</td> -</tr> -</table> - - -<p> -<b>Example:</b> -<p> -<blockquote> +</PRE> +</TD> +</TR> +</TABLE> + +<P> +<STRONG>Example:</STRONG> +<P> +<BLOCKQUOTE> We want to rewrite URLs of the form -<blockquote> -<code>/</code> <em>Language</em> -<code>/~</code> <em>Realname</em> -<code>/.../</code> <em>File</em> -</blockquote> +<BLOCKQUOTE> +<CODE>/</CODE> <EM>Language</EM> +<CODE>/~</CODE> <EM>Realname</EM> +<CODE>/.../</CODE> <EM>File</EM> +</BLOCKQUOTE> into -<blockquote> -<code>/u/</code> <em>Username</em> -<code>/.../</code> <em>File</em> -<code>.</code> <em>Language</em> -</blockquote> -<p> +<BLOCKQUOTE> +<CODE>/u/</CODE> <EM>Username</EM> +<CODE>/.../</CODE> <EM>File</EM> +<CODE>.</CODE> <EM>Language</EM> +</BLOCKQUOTE> +<P> We take the rewrite mapfile from above and save it under -<code>/anywhere/map.real-to-user</code>. Then we only have to add the +<CODE>/path/to/file/map.txt</CODE>. Then we only have to add the following lines to the Apache server configuration file: -<blockquote> -<pre> -RewriteLog /anywhere/rewrite.log -RewriteMap real-to-user txt:/anywhere/map.real-to-host +<BLOCKQUOTE> +<PRE> +RewriteLog /path/to/file/rewrite.log +RewriteMap real-to-user txt:/path/to/file/map.txt RewriteRule ^/([^/]+)/~([^/]+)/(.*)$ /u/${real-to-user:$2|nobody}/$3.$1 -</pre> -</blockquote> -</blockquote> +</PRE> +</BLOCKQUOTE> +</BLOCKQUOTE> -<!--%hypertext --> -<hr> -<!--/%hypertext --> +<P> +<HR NOSHADE SIZE=1> -<center> -<a name="Additional"> -<h1>Additional Features</h1> -</a> -</center> +<CENTER> +<H1><A NAME="Miscelleneous">Miscellaneous</A></H1> +</CENTER> -<a name="EnvVar"> -<h2>Environment Variables</h2> -</a> +<P> +<HR NOSHADE SIZE=1> + +<H2><A NAME="EnvVar">Environment Variables</A></H2> This module keeps track of two additional (non-standard) CGI/SSI environment -variables named <tt>SCRIPT_URL</tt> and <tt>SCRIPT_URI</tt>. These contain -the <em>logical</em> Web-view to the current resource, while the standard CGI/SSI -variables <tt>SCRIPT_NAME</tt> and <tt>SCRIPT_FILENAME</tt> contain the -<em>physical</em> System-view. - -<p> -Notice: These variables hold the URI/URL <em>as they were initially -requested</em>, i.e. in a state <em>before</em> any rewriting. This is +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>, in a state <EM>before</EM> any rewriting. This is important because the rewriting process is primarily used to rewrite logical URLs to physical pathnames. -<p> -<b>Example:</b> +<P> +<STRONG>Example:</STRONG> -<blockquote> -<pre> -SCRIPT_NAME=/v/sw/free/lib/apache/global/u/rse/.www/index.html +<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://en2.en.sdm.de/u/rse/ -</pre> -</blockquote> +SCRIPT_URI=http://en1.engelschall.com/u/rse/ +</PRE> +</BLOCKQUOTE> + +<P> +<HR NOSHADE SIZE=1> +<H2><A NAME="Solutions">Practical Solutions</A></H2> + +There is a comprehensive collection of practical solutions for URL-based +problems available by the author of mod_rewrite. Here you will find real-life +rulesets and additional information. + +<BLOCKQUOTE> +<STRONG>Apache URL Rewriting Guide</STRONG><BR> +<STRONG><A HREF="http://www.engelschall.com/pw/apache/rewriteguide/" + >http://www.engelschall.com/pw/apache/rewriteguide/</A></STRONG> +</BLOCKQUOTE> <HR> + <H3 ALIGN="CENTER"> - Apache HTTP Server Version 1.2 + 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> +</BLOCKQUOTE><!-- page indentation --> </BODY> </HTML> <!--/%hypertext --> |