3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<?xml version="1.0"?>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<!DOCTYPE modulesynopsis SYSTEM "/style/modulesynopsis.dtd">

a7835c7a8cf86045fdaee65dc2839bfe6314fb1end<?xml-stylesheet type="text/xsl" href="/style/manual.en.xsl"?>

a7835c7a8cf86045fdaee65dc2839bfe6314fb1end

117a9c5156c08125e2060ff892adac4634b7ad2dnd

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<modulesynopsis metafile="mod_rewrite.xml.meta">

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<name>mod_rewrite</name>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<description>Provides a rule-based rewriting engine to rewrite requested

3fa58e00171aebf3b2cfa90035ed530f5b1f651dsliveURLs on the fly</description>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<status>Extension</status>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<sourcefile>mod_rewrite.c</sourcefile>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<identifier>rewrite_module</identifier>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<compatibility>Available in Apache 1.3 and later</compatibility>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<summary>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <p>The <module>mod_rewrite</module> module uses a rule-based rewriting

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive engine, based on a regular-expression parser, to rewrite requested URLs on

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive the fly. By default, <module>mod_rewrite</module> maps a URL to a filesystem

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive path. However, it can also be used to redirect one URL to another URL, or

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive to invoke an internal proxy fetch.</p>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <p><module>mod_rewrite</module> provides a flexible and powerful way to

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive manipulate URLs using an unlimited number of rules. Each rule can have an

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive unlimited number of attached rule conditions, to allow you to rewrite URL

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive based on server variables, environment variables, HTTP headers, or time

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive stamps.</p>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <p><module>mod_rewrite</module> operates on the full URL path, including the

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive path-info section. A rewrite rule can be invoked in

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <code>httpd.conf</code> or in <code>.htaccess</code>. The path generated

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive by a rewrite rule can include a query string, or can lead to internal

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive sub-processing, external request redirection, or internal proxy

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive throughput.</p>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <p>Further details, discussion, and examples, are provided in the

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <a href="/rewrite/">detailed mod_rewrite documentation</a>.</p>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive</summary>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<directivesynopsis>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<name>RewriteEngine</name>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<description>Enables or disables runtime rewriting engine</description>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<syntax>RewriteEngine on|off</syntax>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<default>RewriteEngine off</default>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<contextlist><context>server config</context><context>virtual host</context>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<context>directory</context><context>.htaccess</context></contextlist>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<override>FileInfo</override>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<usage>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <p>The <directive>RewriteEngine</directive> directive enables or

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive disables the runtime rewriting engine. If it is set to

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <code>off</code> this module does no runtime processing at

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive all. It does not even update the <code>SCRIPT_URx</code>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive environment variables.</p>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <p>Use this directive to disable the module instead of

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive commenting out all the <directive

1cb160a981947e75a8353da3fe40a653aa87100eslive module="mod_rewrite">RewriteRule</directive> directives!</p>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

46d1ef8cb385aa2f519ce7d355afc51f144bd938slive <p>Note that rewrite configurations are not

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive inherited by virtual hosts. This means that you need to have a

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <code>RewriteEngine on</code> directive for each virtual host

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive in which you wish to use rewrite rules.</p>

1cb160a981947e75a8353da3fe40a653aa87100eslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <p><directive>RewriteMap</directive> directives of the type <code>prg</code>

1cb160a981947e75a8353da3fe40a653aa87100eslive are not started during server initialization if they're defined in a

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive context that does not have <directive>RewriteEngine</directive> set to

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <code>on</code></p>

46d1ef8cb385aa2f519ce7d355afc51f144bd938slive</usage>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive</directivesynopsis>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<directivesynopsis>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<name>RewriteOptions</name>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<description>Sets some special options for the rewrite engine</description>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<syntax>RewriteOptions <var>Options</var></syntax>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<contextlist><context>server config</context><context>virtual host</context>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<context>directory</context><context>.htaccess</context></contextlist>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<override>FileInfo</override>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<compatibility><code>MaxRedirects</code> is no longer available in version 2.1 and

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslivelater</compatibility>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<usage>

5e9423b4ca454c6416a2dc465dea1b1d34cec7a9slive

5e9423b4ca454c6416a2dc465dea1b1d34cec7a9slive <p>The <directive>RewriteOptions</directive> directive sets some

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive special options for the current per-server or per-directory

58842e03db54033d15cc224d997f467abc88a97aslive configuration. The <em>Option</em> string can currently

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive only be one of the following:</p>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <dl>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <dt><code>inherit</code></dt>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <dd>This forces the current configuration to inherit the

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive configuration of the parent. In per-virtual-server context,

46d1ef8cb385aa2f519ce7d355afc51f144bd938slive this means that the maps, conditions and rules of the main

1c6a10274e908898347be82bc82bc7ae18c66410slive server are inherited. In per-directory context this means

1c6a10274e908898347be82bc82bc7ae18c66410slive that conditions and rules of the parent directory's

1c6a10274e908898347be82bc82bc7ae18c66410slive <code>.htaccess</code> configuration or

1c6a10274e908898347be82bc82bc7ae18c66410slive <directive type="section" module="core">Directory</directive>

1c6a10274e908898347be82bc82bc7ae18c66410slive sections are inherited. The inherited rules are virtually copied

1c6a10274e908898347be82bc82bc7ae18c66410slive to the section where this directive is being used. If used in

1c6a10274e908898347be82bc82bc7ae18c66410slive combination with local rules, the inherited rules are copied behind

1c6a10274e908898347be82bc82bc7ae18c66410slive the local rules. The position of this directive - below or above

1c6a10274e908898347be82bc82bc7ae18c66410slive of local rules - has no influence on this behavior. If local

1c6a10274e908898347be82bc82bc7ae18c66410slive rules forced the rewriting to stop, the inherited rules won't

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive be processed.</dd>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive </dl>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive</usage>

46d1ef8cb385aa2f519ce7d355afc51f144bd938slive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive</directivesynopsis>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<directivesynopsis>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<name>RewriteLog</name>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<description>Sets the name of the file used for logging rewrite engine

3fa58e00171aebf3b2cfa90035ed530f5b1f651dsliveprocessing</description>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<syntax>RewriteLog <em>file-path</em></syntax>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<contextlist><context>server config</context><context>virtual host</context>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive</contextlist>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<usage>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <p>The <directive>RewriteLog</directive> directive sets the name

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive of the file to which the server logs any rewriting actions it

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive performs. If the name does not begin with a slash

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive ('<code>/</code>') then it is assumed to be relative to the

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <em>Server Root</em>. The directive should occur only once per

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive server config.</p>

01979b991e320f79fe2c1ae2afc298e8651bd69aslive

01979b991e320f79fe2c1ae2afc298e8651bd69aslive<note> To disable the logging of

01979b991e320f79fe2c1ae2afc298e8651bd69aslive rewriting actions it is not recommended to set

01979b991e320f79fe2c1ae2afc298e8651bd69aslive <em>Filename</em> to <code>/dev/null</code>, because

01979b991e320f79fe2c1ae2afc298e8651bd69aslive although the rewriting engine does not then output to a

01979b991e320f79fe2c1ae2afc298e8651bd69aslive logfile it still creates the logfile output internally.

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <strong>This will slow down the server with no advantage

01979b991e320f79fe2c1ae2afc298e8651bd69aslive to the administrator!</strong> To disable logging either

01979b991e320f79fe2c1ae2afc298e8651bd69aslive remove or comment out the <directive>RewriteLog</directive>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive directive or use <code>RewriteLogLevel 0</code>!

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive</note>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<note type="securitywarning"><title>Security</title>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dsliveSee the <a href="/misc/security_tips.html">Apache Security Tips</a>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslivedocument for details on how your security could be compromised if the

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslivedirectory where logfiles are stored is writable by anyone other than

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslivethe user that starts the server.

01979b991e320f79fe2c1ae2afc298e8651bd69aslive</note>

01979b991e320f79fe2c1ae2afc298e8651bd69aslive

01979b991e320f79fe2c1ae2afc298e8651bd69aslive<example><title>Example</title>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dsliveRewriteLog "/usr/local/var/apache/logs/rewrite.log"

01979b991e320f79fe2c1ae2afc298e8651bd69aslive</example>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive</usage>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive</directivesynopsis>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<directivesynopsis>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<name>RewriteLogLevel</name>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<description>Sets the verbosity of the log file used by the rewrite

3fa58e00171aebf3b2cfa90035ed530f5b1f651dsliveengine</description>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<syntax>RewriteLogLevel <em>Level</em></syntax>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<default>RewriteLogLevel 0</default>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<contextlist><context>server config</context><context>virtual host</context>

368bcafaedaee463f769c1b5f3547b9970df90d0slive</contextlist>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

b3137f48abe3090c5531392e57ff0fefd76f59ebnd<usage>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <p>The <directive>RewriteLogLevel</directive> directive sets the

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive verbosity level of the rewriting logfile. The default level 0

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive means no logging, while 9 or more means that practically all

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive actions are logged.</p>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <p>To disable the logging of rewriting actions simply set

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <em>Level</em> to 0. This disables all rewrite action

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive logs.</p>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<note> Using a high value for

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <em>Level</em> will slow down your Apache server

b3137f48abe3090c5531392e57ff0fefd76f59ebnd dramatically! Use the rewriting logfile at a

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive <em>Level</em> greater than 2 only for debugging!

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive</note>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<example><title>Example</title>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dsliveRewriteLogLevel 3

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive</example>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive</usage>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive</directivesynopsis>

46d1ef8cb385aa2f519ce7d355afc51f144bd938slive

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<directivesynopsis>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<name>RewriteLock</name>

3fa58e00171aebf3b2cfa90035ed530f5b1f651dslive<description>Sets the name of the lock file used for <directive

1cb160a981947e75a8353da3fe40a653aa87100eslivemodule="mod_rewrite">RewriteMap</directive>

1cb160a981947e75a8353da3fe40a653aa87100eslivesynchronization</description>

1cb160a981947e75a8353da3fe40a653aa87100eslive<syntax>RewriteLock <em>file-path</em></syntax>

1cb160a981947e75a8353da3fe40a653aa87100eslive<contextlist><context>server config</context></contextlist>

1cb160a981947e75a8353da3fe40a653aa87100eslive

1cb160a981947e75a8353da3fe40a653aa87100eslive<usage>

1cb160a981947e75a8353da3fe40a653aa87100eslive <p>This directive sets the filename for a synchronization

b3137f48abe3090c5531392e57ff0fefd76f59ebnd lockfile which mod_rewrite needs to communicate with <directive

1cb160a981947e75a8353da3fe40a653aa87100eslive module="mod_rewrite">RewriteMap</directive>

1cb160a981947e75a8353da3fe40a653aa87100eslive <em>programs</em>. Set this lockfile to a local path (not on a

1cb160a981947e75a8353da3fe40a653aa87100eslive NFS-mounted device) when you want to use a rewriting

1cb160a981947e75a8353da3fe40a653aa87100eslive map-program. It is not required for other types of rewriting

1cb160a981947e75a8353da3fe40a653aa87100eslive maps.</p>

1cb160a981947e75a8353da3fe40a653aa87100eslive</usage>

1cb160a981947e75a8353da3fe40a653aa87100eslive

1cb160a981947e75a8353da3fe40a653aa87100eslive</directivesynopsis>

1cb160a981947e75a8353da3fe40a653aa87100eslive

1cb160a981947e75a8353da3fe40a653aa87100eslive<directivesynopsis>

1cb160a981947e75a8353da3fe40a653aa87100eslive<name>RewriteMap</name>

1cb160a981947e75a8353da3fe40a653aa87100eslive<description>Defines a mapping function for key-lookup</description>

1cb160a981947e75a8353da3fe40a653aa87100eslive<syntax>RewriteMap <em>MapName</em> <em>MapType</em>:<em>MapSource</em>

1cb160a981947e75a8353da3fe40a653aa87100eslive</syntax>

1cb160a981947e75a8353da3fe40a653aa87100eslive<contextlist><context>server config</context><context>virtual host</context>

1cb160a981947e75a8353da3fe40a653aa87100eslive</contextlist>

1cb160a981947e75a8353da3fe40a653aa87100eslive<compatibility>The choice of different dbm types is available in

1cb160a981947e75a8353da3fe40a653aa87100esliveApache 2.0.41 and later</compatibility>

1cb160a981947e75a8353da3fe40a653aa87100eslive

1cb160a981947e75a8353da3fe40a653aa87100eslive<usage>

1cb160a981947e75a8353da3fe40a653aa87100eslive <p>The <directive>RewriteMap</directive> directive defines a

1cb160a981947e75a8353da3fe40a653aa87100eslive <em>Rewriting Map</em> which can be used inside rule

1cb160a981947e75a8353da3fe40a653aa87100eslive substitution strings by the mapping-functions to

1cb160a981947e75a8353da3fe40a653aa87100eslive insert/substitute fields through a key lookup. The source of

1cb160a981947e75a8353da3fe40a653aa87100eslive this lookup can be of various types.</p>

1cb160a981947e75a8353da3fe40a653aa87100eslive

1cb160a981947e75a8353da3fe40a653aa87100eslive <p>The <a id="mapfunc" name="mapfunc"><em>MapName</em></a> is

1cb160a981947e75a8353da3fe40a653aa87100eslive the name of the map and will be used to specify a

mapping-function for the substitution strings of a rewriting

rule via one of the following constructs:</p>

<p class="indent">

<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>

</p>

<p>When such a construct occurs, the map <em>MapName</em> is

consulted and the key <em>LookupKey</em> is looked-up. If the

key is found, the map-function construct is substituted by

<em>SubstValue</em>. If the key is not found then it is

substituted by <em>DefaultValue</em> or by the empty string

if no <em>DefaultValue</em> was specified.</p>

<p>For example, you might define a

<directive>RewriteMap</directive> as:</p>

<example>

RewriteMap examplemap txt:/path/to/file/map.txt

</example>

<p>You would then be able to use this map in a

<directive>RewriteRule</directive> as follows:</p>

<example>

RewriteRule ^/ex/(.*) ${examplemap:$1}

</example>

<p>The following combinations for <em>MapType</em> and

<em>MapSource</em> can be used:</p>

<ul>

<li>

<strong>Standard Plain Text</strong><br />

MapType: <code>txt</code>, MapSource: Unix filesystem

path to valid regular file

<p>This is the standard rewriting map feature where the

<em>MapSource</em> is a plain ASCII file containing

either blank lines, comment lines (starting with a '#'

character) or pairs like the following - one per

line.</p>

<p class="indent">

<strong><em>MatchingKey</em>

<em>SubstValue</em></strong>

</p>

<example><title>Example</title>

<pre>

##

## map.txt -- rewriting map

##

Ralf.S.Engelschall rse # Bastard Operator From Hell

Mr.Joe.Average joe # Mr. Average

</pre>

</example>

<example>

RewriteMap real-to-user txt:/path/to/file/map.txt

</example>

</li>

<li>

<strong>Randomized Plain Text</strong><br />

MapType: <code>rnd</code>, MapSource: Unix filesystem

path to valid regular file

<p>This is identical to the Standard Plain Text variant

above but with a special post-processing feature: After

looking up a value it is parsed according to contained

``<code>|</code>'' characters which have the meaning of

``or''. In other words they indicate a set of

alternatives from which the actual returned value is

chosen randomly. For example, you might use the following map

file and directives to provide a random load balancing between

several back-end server, via a reverse-proxy. Images are sent

to one of the servers in the 'static' pool, while everything

else is sent to one of the 'dynamic' pool.</p>

<p>Example:</p>

<example><title>Rewrite map file</title>

<pre>

##

## map.txt -- rewriting map

##

static www1|www2|www3|www4

dynamic www5|www6

</pre>

</example>

<example><title>Configuration directives</title>

RewriteMap servers rnd:/path/to/file/map.txt<br />

<br />

RewriteRule ^/(.*\.(png|gif|jpg)) http://${servers:static}/$1

[NC,P,L]<br />

RewriteRule ^/(.*) http://${servers:dynamic}/$1 [P,L]

</example>

</li>

<li>

<strong>Hash File</strong><br /> MapType:

<code>dbm[=<em>type</em>]</code>, MapSource: Unix filesystem

path to valid regular file

<p>Here the source is a binary format DBM 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. The <em>type</em> can be sdbm, gdbm, ndbm, or

db depending on <a href="/install.html#dbm">compile-time

settings</a>. If the <em>type</em> is omitted, the

compile-time default will be chosen.</p>

<p>To create a dbm file from a source text file, use the <a

href="/programs/httxt2dbm.html">httxt2dbm</a> utility.</p>

<example>

$ httxt2dbm -i mapfile.txt -o mapfile.map

</example>

</li>

<li>

<strong>Internal Function</strong><br />

MapType: <code>int</code>, MapSource: Internal Apache

function

<p>Here, the source is an internal Apache function.

Currently you cannot create your own, but the following

functions already exist:</p>

<ul>

<li><strong>toupper</strong>:<br />

Converts the key to all upper case.</li>

<li><strong>tolower</strong>:<br />

Converts the key to all lower case.</li>

<li><strong>escape</strong>:<br />

Translates special characters in the key to

hex-encodings.</li>

<li><strong>unescape</strong>:<br />

Translates hex-encodings in the key back to

special characters.</li>

</ul>

</li>

<li>

<strong>External Rewriting Program</strong><br />

MapType: <code>prg</code>, MapSource: Unix filesystem

path to valid regular file

<p>Here the source is a program, not a map file. To

create it you can use a language of your choice, but

the result has to be an executable program (either

object-code or a script with the magic cookie trick

'<code>#!/path/to/interpreter</code>' as the first

line).</p>

<p>This program is started once, when the Apache server

is started, and then communicates with the rewriting engine

via its <code>stdin</code> and <code>stdout</code>

file-handles. For each map-function lookup it will

receive the key to lookup as a newline-terminated string

on <code>stdin</code>. It then has to give back the

looked-up value as a newline-terminated string on

<code>stdout</code> or the four-character string

``<code>NULL</code>'' if it fails (<em>i.e.</em>, there

is no corresponding value for the given key).</p>

<p>External rewriting programs are not started if they're defined in a

context that does not have <directive>RewriteEngine</directive> set to

<code>on</code></p>.

<p>A trivial program which will implement a 1:1 map (<em>i.e.</em>,

key == value) could be:</p>

<example>

<pre>

#!/usr/bin/perl

$| = 1;

while (&lt;STDIN&gt;) {

# ...put here any transformations or lookups...

print $_;

}

</pre>

</example>

<p>But be very careful:</p>

<ol>

<li>``<em>Keep it simple, stupid</em>'' (KISS).

If this program hangs, it will cause Apache to hang

when trying to use the relevant rewrite rule.</li>

<li>A common mistake is to use buffered I/O on

<code>stdout</code>. Avoid this, as it will cause a deadloop!

``<code>$|=1</code>'' is used above, to prevent this.</li>

<li>The <directive

module="mod_rewrite">RewriteLock</directive> directive can

be used to define a lockfile which mod_rewrite can use to synchronize

communication with the mapping program. By default no such

synchronization takes place.</li>

</ol>

</li>

<li>

<p><strong>SQL Query</strong><br />

MapType: <code>dbd</code> or <code>fastdbd</code>,

MapSource: An SQL SELECT statement that takes a single

argument and returns a single value.</p>

<p>This uses <module>mod_dbd</module> to implement a rewritemap

by lookup in an SQL database. There are two forms:

<code>fastdbd</code> caches database lookups internally,

<code>dbd</code> doesn't. So <code>dbd</code> incurs a

performance penalty but responds immediately if the database

contents are updated, while <code>fastdbd</code> is more

efficient but won't re-read database contents until server

restart.</p>

<p>If a query returns more than one row, a random row from

the result set is used.</p>

<example>

<title>Example</title>

RewriteMap myquery "fastdbd:SELECT destination FROM rewrite WHERE source = %s"

</example>

</li>

</ul>

<p>The <directive>RewriteMap</directive> directive can occur more than

once. For each mapping-function use one

<directive>RewriteMap</directive> 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>

<note><title>Note</title> For plain text and DBM format files the

looked-up keys are cached in-core until the <code>mtime</code> of the

mapfile changes or the server does a restart. This way you can have

map-functions in rules which are used for <strong>every</strong>

request. This is no problem, because the external lookup only happens

once!

</note>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>RewriteBase</name>

<description>Sets the base URL for per-directory rewrites</description>

<syntax>RewriteBase <em>URL-path</em></syntax>

<default>None</default>

<contextlist><context>directory</context><context>.htaccess</context>

</contextlist>

<override>FileInfo</override>

<usage>

<p>The <directive>RewriteBase</directive> directive explicitly

sets the base URL for per-directory rewrites.

When you use a <directive module="mod_rewrite">RewriteRule</directive>

in a <code>.htaccess</code> file, <module>mod_rewrite</module> strips off

the local directory prefix before processing, then rewrites the rest of

the URL. When the rewrite is completed, <module>mod_rewrite</module>

automatically adds the local directory prefix back on to the path.</p>

<p>If your URL path does not exist on the filesystem,

you must use <directive>RewriteBase</directive> in every

<code>.htaccess</code> file where you want to use <directive

module="mod_rewrite">RewriteRule</directive> directives. </p>

<p>The example below demonstrates how to map

http://example.com/foo/index.html to

/home/www/example/newsite.html, in a <code>.htaccess</code> file. This

assumes that the content available at

http://example.com/ is on disk at /home/www/example/</p>

<example>

<pre>

RewriteEngine On

RewriteBase /foo/

RewriteRule ^index\.html$ newsite.html

</pre>

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>RewriteCond</name>

<description>Defines a condition under which rewriting will take place

</description>

<syntax> RewriteCond

<em>TestString</em> <em>CondPattern</em></syntax>

<contextlist><context>server config</context><context>virtual host</context>

<context>directory</context><context>.htaccess</context></contextlist>

<override>FileInfo</override>

<usage>

<p>The <directive>RewriteCond</directive> directive defines a

rule condition. One or more <directive>RewriteCond</directive>

can precede a <directive module="mod_rewrite">RewriteRule</directive>

directive. The following rule is then only used if both

the current state of the URI matches its pattern, <strong

>and</strong> if these conditions are met.</p>

<p><em>TestString</em> is a string which can contain the

following expanded constructs in addition to plain text:</p>

<ul>

<li>

<strong>RewriteRule backreferences</strong>: These are

backreferences of the form <strong><code>$N</code></strong>

(0 &lt;= N &lt;= 9), which provide access to the grouped

parts (in parentheses) of the pattern, from the

<code>RewriteRule</code> which is subject to the current

set of <code>RewriteCond</code> conditions.

</li>

<li>

<strong>RewriteCond backreferences</strong>: These are

backreferences of the form <strong><code>%N</code></strong>

(1 &lt;= N &lt;= 9), which provide access to the grouped

parts (again, in parentheses) of the pattern, from the last matched

<code>RewriteCond</code> in the current set

of conditions.

</li>

<li>

<strong>RewriteMap expansions</strong>: These are

expansions of the form <strong><code

>${mapname:key|default}</code></strong>.

See <a href="#mapfunc">the documentation for

RewriteMap</a> for more details.

</li>

<li>

<strong>Server-Variables</strong>: These are variables of

the form

<strong><code>%{</code> <em>NAME_OF_VARIABLE</em>

<code>}</code></strong>

where <em>NAME_OF_VARIABLE</em> can be a string taken

from the following list:

<table>

<columnspec><column width=".3"/><column width=".3"/>

<column width=".3"/></columnspec>

<tr>

<th>HTTP headers:</th> <th>connection &amp; request:</th> <th></th>

</tr>

<tr>

<td>

HTTP_USER_AGENT<br />

HTTP_REFERER<br />

HTTP_COOKIE<br />

HTTP_FORWARDED<br />

HTTP_HOST<br />

HTTP_PROXY_CONNECTION<br />

HTTP_ACCEPT<br />

</td>

<td>

REMOTE_ADDR<br />

REMOTE_HOST<br />

REMOTE_PORT<br />

REMOTE_USER<br />

REMOTE_IDENT<br />

REQUEST_METHOD<br />

SCRIPT_FILENAME<br />

PATH_INFO<br />

QUERY_STRING<br />

AUTH_TYPE<br />

</td>

<td></td>

</tr>

<tr>

<th>server internals:</th> <th>date and time:</th> <th>specials:</th>

</tr>

<tr>

<td>

DOCUMENT_ROOT<br />

SERVER_ADMIN<br />

SERVER_NAME<br />

SERVER_ADDR<br />

SERVER_PORT<br />

SERVER_PROTOCOL<br />

SERVER_SOFTWARE<br />

</td>

<td>

TIME_YEAR<br />

TIME_MON<br />

TIME_DAY<br />

TIME_HOUR<br />

TIME_MIN<br />

TIME_SEC<br />

TIME_WDAY<br />

TIME<br />

</td>

<td>

API_VERSION<br />

THE_REQUEST<br />

REQUEST_URI<br />

REQUEST_FILENAME<br />

IS_SUBREQ<br />

HTTPS<br />

</td>

</tr>

</table>

<p>These variables all

correspond to the similarly named HTTP

MIME-headers, C variables of the Apache server or

<code>struct tm</code> fields of the Unix system.

Most are documented elsewhere in the Manual or in

the CGI specification. Those that are special to

mod_rewrite include those below.</p>

<note>

<dl>

<dt><code>IS_SUBREQ</code></dt>

<dd>Will contain the text "true" if the request

currently being processed is a sub-request,

"false" otherwise. Sub-requests may be generated

by modules that need to resolve additional files

or URIs in order to complete their tasks.</dd>

<dt><code>API_VERSION</code></dt>

<dd>This is the version of the Apache module API

(the internal interface between server and

module) in the current httpd build, as defined in

include/ap_mmn.h. The module API version

corresponds to the version of Apache in use (in

the release version of Apache 1.3.14, for

instance, it is 19990320:10), but is mainly of

interest to module authors.</dd>

<dt><code>THE_REQUEST</code></dt>

<dd>The full HTTP request line sent by the

browser to the server (e.g., "<code>GET

/index.html HTTP/1.1</code>"). This does not

include any additional headers sent by the

browser.</dd>

<dt><code>REQUEST_URI</code></dt>

<dd>The resource requested in the HTTP request

line. (In the example above, this would be

"/index.html".)</dd>

<dt><code>REQUEST_FILENAME</code></dt>

<dd>The full local filesystem path to the file or

script matching the request.</dd>

<dt><code>HTTPS</code></dt>

<dd>Will contain the text "on" if the connection is

using SSL/TLS, or "off" otherwise. (This variable

can be safely used regardless of whether or not

<module>mod_ssl</module> is loaded).</dd>

</dl>

</note>

</li>

</ul>

<p>Other things you should be aware of:</p>

<ol>

<li>

<p>The variables SCRIPT_FILENAME and REQUEST_FILENAME

contain the same value - the value of the

<code>filename</code> field of the internal

<code>request_rec</code> structure of the Apache server.

The first name is the commonly known CGI variable name

while the second is the appropriate counterpart of

REQUEST_URI (which contains the value of the

<code>uri</code> field of <code>request_rec</code>).</p>

<p>If a substitution occurred and the rewriting continues,

the value of both variables will be updated accordingly.</p>

<p>If used in per-server context (<em>i.e.</em>, before the

request is mapped to the filesystem) SCRIPT_FILENAME and

REQUEST_FILENAME cannot contain the full local filesystem

path since the path is unknown at this stage of processing.

Both variables will initially contain the value of REQUEST_URI

in that case. In order to obtain the full local filesystem

path of the request in per-server context, use an URL-based

look-ahead <code>%{LA-U:REQUEST_FILENAME}</code> to determine

the final value of REQUEST_FILENAME.</p></li>

<li>

<code>%{ENV:variable}</code>, where <em>variable</em> can be

any environment variable, is also available.

This is looked-up via internal

Apache structures and (if not found there) via

<code>getenv()</code> from the Apache server process.</li>

<li>

<code>%{SSL:variable}</code>, where <em>variable</em> is the

name of an <a href="mod_ssl.html#envvars">SSL environment

variable</a>, can be used whether or not

<module>mod_ssl</module> is loaded, but will always expand to

the empty string if it is not. Example:

<code>%{SSL:SSL_CIPHER_USEKEYSIZE}</code> may expand to

<code>128</code>.</li>

<li>

<code>%{HTTP:header}</code>, where <em>header</em> can be

any HTTP MIME-header name, can always be used to obtain the

value of a header sent in the HTTP request.

Example: <code>%{HTTP:Proxy-Connection}</code> is

the value of the HTTP header

``<code>Proxy-Connection:</code>''.

<p>If a HTTP header is used in a condition this header is added to

the Vary header of the response in case the condition evaluates to

to true for the request. It is <strong>not</strong> added if the

condition evaluates to false for the request. Adding the HTTP header

to the Vary header of the response is needed for proper caching.</p>

<p>It has to be kept in mind that conditions follow a short circuit

logic in the case of the '<strong><code>ornext|OR</code></strong>' flag

so that certain conditions might not be evaluated at all.</p></li>

<li>

<code>%{LA-U:variable}</code> can be used for look-aheads which perform

an internal (URL-based) sub-request to determine the final

value of <em>variable</em>. This can be used to access

variable for rewriting which is not available at the current

stage, but will be set in a later phase.

<p>For instance, to rewrite according to the

<code>REMOTE_USER</code> variable from within the

per-server context (<code>httpd.conf</code> file) you must

use <code>%{LA-U:REMOTE_USER}</code> - this

variable is set by the authorization phases, which come

<em>after</em> the URL translation phase (during which mod_rewrite

operates).</p>

<p>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> in that context.</p></li>

<li>

<code>%{LA-F:variable}</code> can be used to perform an internal

(filename-based) sub-request, to determine the final value

of <em>variable</em>. Most of the time, this is the same as

LA-U above.</li>

</ol>

<p><em>CondPattern</em> is the condition pattern,

a regular expression which is applied to the

current instance of the <em>TestString</em>.

<em>TestString</em> is first evaluated, before being matched against

<em>CondPattern</em>.</p>

<p><strong>Remember:</strong> <em>CondPattern</em> is a

<em>perl compatible regular expression</em> with some

additions:</p>

<ol>

<li>You can prefix the pattern string with a

'<code>!</code>' character (exclamation mark) to specify a

<strong>non</strong>-matching pattern.</li>

<li>

There are some special variants of <em>CondPatterns</em>.

Instead of real regular expression strings you can also

use one of the following:

<ul>

<li>'<strong>&lt;CondPattern</strong>' (lexicographically

precedes)<br />

Treats the <em>CondPattern</em> as a plain string and

compares it lexicographically to <em>TestString</em>. True if

<em>TestString</em> lexicographically precedes

<em>CondPattern</em>.</li>

<li>'<strong>&gt;CondPattern</strong>' (lexicographically

follows)<br />

Treats the <em>CondPattern</em> as a plain string and

compares it lexicographically to <em>TestString</em>. True if

<em>TestString</em> lexicographically follows

<em>CondPattern</em>.</li>

<li>'<strong>=CondPattern</strong>' (lexicographically

equal)<br />

Treats the <em>CondPattern</em> as a plain string and

compares it lexicographically to <em>TestString</em>. True if

<em>TestString</em> is lexicographically equal to

<em>CondPattern</em> (the two strings are exactly

equal, character for character). If <em>CondPattern</em>

is <code>""</code> (two quotation marks) this

compares <em>TestString</em> to the empty string.</li>

<li>'<strong>-d</strong>' (is

<strong>d</strong>irectory)<br />

Treats the <em>TestString</em> as a pathname and tests

whether or not it exists, and is a directory.</li>

<li>'<strong>-f</strong>' (is regular

<strong>f</strong>ile)<br />

Treats the <em>TestString</em> as a pathname and tests

whether or not it exists, and is a regular file.</li>

<li>'<strong>-s</strong>' (is regular file, with

<strong>s</strong>ize)<br />

Treats the <em>TestString</em> as a pathname and tests

whether or not it exists, and is a regular file with size greater

than zero.</li>

<li>'<strong>-l</strong>' (is symbolic

<strong>l</strong>ink)<br />

Treats the <em>TestString</em> as a pathname and tests

whether or not it exists, and is a symbolic link.</li>

<li>'<strong>-x</strong>' (has e<strong>x</strong>ecutable

permissions)<br />

Treats the <em>TestString</em> as a pathname and tests

whether or not it exists, and has executable permissions.

These permissions are determined according to

the underlying OS.</li>

<li>'<strong>-F</strong>' (is existing file, via

subrequest)<br />

Checks whether or not <em>TestString</em> is a valid file,

accessible via all the server's currently-configured

access controls for that path. This uses an internal

subrequest to do the check, so use it with care -

it can impact your server's performance!</li>

<li>'<strong>-U</strong>' (is existing URL, via

subrequest)<br />

Checks whether or not <em>TestString</em> is a valid URL,

accessible via all the server's currently-configured

access controls for that path. This uses an internal

subrequest to do the check, so use it with care -

it can impact your server's performance!</li>

</ul>

<note><title>Note:</title>

All of these tests can

also be prefixed by an exclamation mark ('!') to

negate their meaning.

</note>

</li>

<li>You can also set special flags for

<em>CondPattern</em> by appending

<strong><code>[</code><em>flags</em><code>]</code></strong>

as the third argument to the <code>RewriteCond</code>

directive, where <em>flags</em> is a comma-separated list of any of the

following flags:

<ul>

<li>'<strong><code>nocase|NC</code></strong>'

(<strong>n</strong>o <strong>c</strong>ase)<br />

This makes the test case-insensitive - differences

between 'A-Z' and 'a-z' are ignored, both in the

expanded <em>TestString</em> and the <em>CondPattern</em>.

This flag is effective only for comparisons between

<em>TestString</em> and <em>CondPattern</em>. It has no

effect on filesystem and subrequest checks.</li>

<li>

'<strong><code>ornext|OR</code></strong>'

(<strong>or</strong> next condition)<br />

Use this to combine rule conditions with a local OR

instead of the implicit AND. Typical example:

<example>

<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>

</example>

Without this flag you would have to write the condition/rule

pair three times.

</li>

<li>'<strong><code>novary|NV</code></strong>'

(<strong>n</strong>o <strong>v</strong>ary)<br />

If a HTTP header is used in the condition, this flag prevents

this header from being added to the Vary header of the response. <br />

Using this flag might break proper caching of the response if

the representation of this response varies on the value of this header.

So this flag should be only used if the meaning of the Vary header

is well understood.

</li>

</ul>

</li>

</ol>

<p><strong>Example:</strong></p>

<p>To rewrite the Homepage of a site according to the

``<code>User-Agent:</code>'' header of the request, you can

use the following: </p>

<example>

<pre>

RewriteCond %{HTTP_USER_AGENT} ^Mozilla.*

RewriteRule ^/$ /homepage.max.html [L]

RewriteCond %{HTTP_USER_AGENT} ^Lynx.*

RewriteRule ^/$ /homepage.min.html [L]

RewriteRule ^/$ /homepage.std.html [L]

</pre>

</example>

<p>Explanation: If you use a browser which identifies itself

as 'Mozilla' (including Netscape Navigator, Mozilla etc), then you

get the max homepage (which could include frames, or other special

features).

If you use the Lynx browser (which is terminal-based), then

you get the min homepage (which could be a version designed for

easy, text-only browsing).

If neither of these conditions apply (you use any other browser,

or your browser identifies itself as something non-standard), you get

the std (standard) homepage.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>RewriteRule</name>

<description>Defines rules for the rewriting engine</description>

<syntax>RewriteRule

<em>Pattern</em> <em>Substitution</em> [<em>flags</em>]</syntax>

<contextlist><context>server config</context><context>virtual host</context>

<context>directory</context><context>.htaccess</context></contextlist>

<override>FileInfo</override>

<usage>

<p>The <directive>RewriteRule</directive> directive is the real

rewriting workhorse. The directive can occur more than once,

with each instance defining a single rewrite rule. The

order in which these rules are defined is important - this is the order

in which they will be applied at run-time.</p>

<p><a id="patterns" name="patterns"><em>Pattern</em></a> is

a perl compatible <a id="regexp" name="regexp">regular

expression</a>. On the first RewriteRule it is applied to the (%-encoded)

<a href="/directive-dict.html#Syntax">URL-path</a> of the request;

subsequent patterns are applied to the output of the last matched

RewriteRule.</p>

<note><title>What is matched?</title>

<p>The <em>Pattern</em> will initially be matched against the part of the

URL after the hostname and port, and before the query string. If you wish

to match against the hostname, port, or query string, use a

<directive module="mod_rewrite">RewriteCond</directive> with the

<code>%{HTTP_HOST}</code>, <code>%{SERVER_PORT}</code>, or

<code>%{QUERY_STRING}</code> variables respectively.</p>

</note>

<p>For some hints on <glossary ref="regex">regular

expressions</glossary>, see

the <a href="/rewrite/intro.html#regex">mod_rewrite

Introduction</a>.</p>

<p>In mod_rewrite, the NOT character

('<code>!</code>') is also available as a possible pattern

prefix. This enables you to negate a pattern; to say, for instance:

``<em>if the current URL does <strong>NOT</strong> match this

pattern</em>''. This can be used for exceptional cases, where

it is easier to match the negative pattern, or as a last

default rule.</p>

<note><title>Note</title>

When using the NOT character to negate a pattern, you cannot include

grouped wildcard parts in that pattern. This is because, when the

pattern does NOT match (ie, the negation matches), there are no

contents for the groups. Thus, if negated patterns are used, you

cannot use <code>$N</code> in the substitution string!

</note>

<p>The <a id="rhs" name="rhs"><em>Substitution</em></a> of a

rewrite rule is the string that replaces the original URL-path that

was matched by <em>Pattern</em>. The <em>Substitution</em> may

be a:</p>

<dl>

<dt>file-system path</dt>

<dd>Designates the location on the file-system of the resource

to be delivered to the client.</dd>

<dt>URL-path</dt>

<dd>A <directive

module="core">DocumentRoot</directive>-relative path to the

resource to be served. Note that <module>mod_rewrite</module>

tries to guess whether you have specified a file-system path

or a URL-path by checking to see if the first segment of the

path exists at the root of the file-system. For example, if

you specify a <em>Substitution</em> string of

<code>/www/file.html</code>, then this will be treated as a

URL-path <em>unless</em> a directory named <code>www</code>

exists at the root or your file-system, in which case it will

be treated as a file-system path. If you wish other

URL-mapping directives (such as <directive

module="mod_alias">Alias</directive>) to be applied to the

resulting URL-path, use the <code>[PT]</code> flag as

described below.</dd>

<dt>Absolute URL</dt>

<dd>If an absolute URL is specified,

<module>mod_rewrite</module> checks to see whether the

hostname matches the current host. If it does, the scheme and

hostname are stripped out and the resulting path is treated as

a URL-path. Otherwise, an external redirect is performed for

the given URL. To force an external redirect back to the

current host, see the <code>[R]</code> flag below.</dd>

<dt><code>-</code> (dash)</dt>

<dd>A dash indicates that no substitution should be performed

(the existing path is passed through untouched). This is used

when a flag (see below) needs to be applied without changing

the path.</dd>

</dl>

<p>In addition to plain text, the <em>Substition</em> string can include</p>

<ol>

<li>back-references (<code>$N</code>) to the RewriteRule

pattern</li>

<li>back-references (<code>%N</code>) to the last matched

RewriteCond pattern</li>

<li>server-variables as in rule condition test-strings

(<code>%{VARNAME}</code>)</li>

<li><a href="#mapfunc">mapping-function</a> calls

(<code>${mapname:key|default}</code>)</li>

</ol>

<p>Back-references are identifiers of the form

<code>$</code><strong>N</strong>

(<strong>N</strong>=0..9), 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 above.</p>

<p>As already mentioned, all rewrite rules are

applied to the <em>Substitution</em> (in the order in which

they are defined

in the config file). The URL is <strong>completely

replaced</strong> by the <em>Substitution</em> and the

rewriting process continues until all rules have been applied,

or it is explicitly terminated by a

<code><strong>L</strong></code> flag.</p>

<note><title>Modifying the Query String</title>

<p>By default, the query string is passed through unchanged. You

can, however, create URLs in the substitution string containing

a query string part. Simply use a question mark inside the

substitution string to indicate that the following text should

be re-injected into the query string. When you want to erase an

existing query string, end the substitution string with just a

question mark. To combine new and old query strings, use the

<code>[QSA]</code> flag.</p>

</note>

<p>Additionally you can set special <a name="rewriteflags"

id="rewriteflags">actions</a> to be performed by

appending <strong><code>[</code><em>flags</em><code>]</code></strong>

as the third argument to the <code>RewriteRule</code>

directive. <em>Flags</em> is a comma-separated list, surround by square

brackets, of any of the following flags: </p>

<dl>

<dt>'<code>B</code>' (escape backreferences)</dt>

<dd><p>Apache has to unescape URLs before mapping them,

so backreferences will be unescaped at the time they are applied.

Using the B flag, non-alphanumeric characters in backreferences

will be escaped. For example, consider the rule:</p>

<example>

RewriteRule ^(/.*)$ /index.php?show=$1

</example>

<p>This will map <code>/C++</code> to

<code>/index.php?show=/C++</code>. But it will also map

<code>/C%2b%2b</code> to <code>/index.php?show=/C++</code>, because

the <code>%2b</code> has been unescaped. With the B flag, it will

instead map to <code>/index.php?show=/C%2b%2b</code>.</p>

<p>This escaping is particularly necessary in a proxy situation,

when the backend may break if presented with an unescaped URL.</p>

</dd>

<dt>'<code>chain|C</code>'

(chained with next rule)</dt><dd>

This flag chains the current rule with the next rule

(which itself can be chained with the following rule,

and so on). This has the following effect: if a rule

matches, then processing continues as usual -

the flag has no effect. If the rule does

<strong>not</strong> match, then all following chained

rules are skipped. For instance, it can be used to remove the

``<code>.www</code>'' part, inside a per-directory rule set,

when you let an external redirect happen (where the

``<code>.www</code>'' part should not occur!).</dd>

<dt>'<code>cookie|CO=</code><em>NAME</em>:<em>VAL</em>:<em>domain</em>[:<em>lifetime</em>[:<em>path</em>[:<em>secure</em>[:<em>httponly</em>]]]]'

(set cookie)</dt><dd>

This sets a cookie in the client's browser. The cookie's name

is specified by <em>NAME</em> and the value is

<em>VAL</em>. The <em>domain</em> field is the domain of the

cookie, such as '.apache.org', the optional <em>lifetime</em>

is the lifetime of the cookie in minutes (0 means expires at end

of session), and the optional

<em>path</em> is the path of the cookie. If <em>secure</em>

is set to 'secure', 'true' or '1', the cookie is only transmitted via secured

connections. If <em>httponly</em> is set to 'HttpOnly', 'true' or '1', the

<code>HttpOnly</code> flag is used, making the cookie inaccessible

to JavaScript code on browsers that support this feature.</dd>

<dt>'<code>discardpathinfo|DPI'

(discard PATH_INFO)</code></dt><dd>

<p>This flag is available from 2.2.12</p>

<p>In per-directory context, the URI each <directive>RewriteRule</directive>

compares against is the concatenation of the current values of the URI

and PATH_INFO.</p>

<p>The current URI can be the initial URI as requested by the client, the

result of a previous round of mod_rewrite processing, or the result of

a prior rule in the current round of mod_rewrite processing.</p>

<p>In contrast, the PATH_INFO that is appended to the URI before each

rule reflects only the value of PATH_INFO before this round of

mod_rewrite processing. As a consequence, if large portions

of the URI are matched and copied into a substitution in multiple

<directive>RewriteRule</directive> directives, without regard for

which parts of the URI came from the current PATH_INFO, the final

URI may have multiple copies of PATH_INFO appended to it.</p>

<p>Use this flag on any substitution where the PATH_INFO that resulted

from the previous mapping of this request to the filesystem is not of

interest. This flag permanently forgets the PATH_INFO established

before this round of mod_rewrite processing began. PATH_INFO will

not be recalculated until the current round of mod_rewrite processing

completes. Subsequent rules during this round of processing will see

only the direct result of substitutions, without any PATH_INFO

appended.</p></dd>

<dt>

'<code>env|E=</code><em>VAR</em>:<em>VAL</em>'

(set environment variable)</dt><dd>

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 later be dereferenced in many situations, most commonly

from within XSSI (via <code>&lt;!--#echo

var="VAR"--&gt;</code>) or CGI (<code>$ENV{'VAR'}</code>).

You can also dereference the variable in a later RewriteCond pattern, using

<code>%{ENV:VAR}</code>. Use this to strip

information from URLs, while maintaining a record of that information.</dd>

<dt>'<code>forbidden|F</code>' (force URL

to be forbidden)</dt><dd>

This forces the current URL to be forbidden - it immediately

sends back a HTTP response of 403 (FORBIDDEN).

Use this flag in conjunction with

appropriate RewriteConds to conditionally block some

URLs.</dd>

<dt>'<code>gone|G</code>' (force URL to be

gone)</dt><dd>

This forces the current URL to be gone - it

immediately sends back a HTTP response of 410 (GONE). Use

this flag to mark pages which no longer exist as gone.</dd>

<dt>

'<code>handler|H</code>=<em>Content-handler</em>'

(force Content handler)</dt><dd>

Force the Content-handler of the target file to be

<em>Content-handler</em>. For instance, this can be used to

simulate the <module>mod_alias</module> directive

<directive module="mod_alias">ScriptAlias</directive>,

which internally forces all files

inside the mapped directory to have a handler of

``<code>cgi-script</code>''.<br />

If used in per-directory context, there must not be a substitution

which changes the path. Use this flag in per-directory context only

with <code>-</code> (dash) as the substitution, otherwise the request

will fail.</dd>

<dt>'<code>last|L</code>'

(last rule)</dt><dd> Stop the rewriting process

here and don't apply any more rewrite rules. This corresponds

to the Perl <code>last</code> command or the

<code>break</code> command in C. Use this flag to prevent the

currently rewritten URL from being rewritten further by

following rules. Remember, however, that if the

<directive>RewriteRule</directive> generates an internal

redirect (which frequently occurs when rewriting in a

per-directory context), this will reinject the request and

will cause processing to be repeated starting from the first

<directive>RewriteRule</directive>.</dd>

<dt>'<code>next|N</code>'

(next round)</dt><dd>

Re-run the rewriting process (starting again with the

first rewriting rule). This time, the URL to match is no longer

the original URL, but rather the URL returned by the last rewriting rule.

This corresponds to the Perl <code>next</code> command or

the <code>continue</code> command in C. Use

this flag to restart the rewriting process -

to immediately go to the top of the loop.

<strong>Be careful not to create an infinite

loop!</strong></dd>

<dt>'<code>nocase|NC</code>'

(no case)</dt><dd>

This makes the <em>Pattern</em> case-insensitive,

ignoring difference between 'A-Z' and

'a-z' when <em>Pattern</em> is matched against the current

URL.</dd>

<dt>

'<code>noescape|NE</code>'

(no URI escaping of

output)</dt><dd>

This flag prevents mod_rewrite from applying the usual URI

escaping rules to the result of a rewrite. Ordinarily,

special characters (such as '%', '$', ';', and so on)

will be escaped into their hexcode equivalents ('%25',

'%24', and '%3B', respectively); this flag prevents this

from happening. This allows percent symbols to appear in

the output, as in

<example>

RewriteRule ^/foo/(.*) /bar?arg=P1\%3d$1 [R,NE]

</example>

which would turn '<code>/foo/zed</code>' into a safe

request for '<code>/bar?arg=P1=zed</code>'.

</dd>

<dt>

'<code>nosubreq|NS</code>'

(not for internal

sub-requests)</dt><dd>

<p>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 <module>mod_dir</module> tries to find out

information about possible directory default files

(<code>index.xxx</code> files). On sub-requests it is not

always useful, and can even cause errors, if

the complete set of rules are applied. Use this flag to

exclude some rules.</p>

<p>To decide whether or not to use this rule: if you

prefix URLs with CGI-scripts, to force them to be

processed by the CGI-script, it's likely that you

will run into problems (or significant overhead) on

sub-requests. In these cases, use this flag.</p>

</dd>

<dt>

'<code>proxy|P</code>' (force

proxy)</dt><dd>

This flag forces the substitution part to be internally

sent as a proxy request and immediately (rewrite

processing stops here) put through the <a

href="mod_proxy.html">proxy module</a>. You must make

sure that the substitution string is a valid URI

(typically starting with

<code>http://</code><em>hostname</em>) which can be

handled by the Apache proxy module. If not, you will 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 remote content into the namespace of the local

server.

<p>Note: <module>mod_proxy</module> must be enabled in order

to use this flag.</p>

</dd>

<dt>

'<code>passthrough|PT</code>'

(pass through to next

handler)</dt><dd>

This flag forces the rewrite 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

enable post-processing of the output of

<code>RewriteRule</code> directives, using

<code>Alias</code>, <code>ScriptAlias</code>,

<code>Redirect</code>, and other directives from

various URI-to-filename translators. For example, to rewrite

<code>/abc</code> to <code>/def</code> using

<module>mod_rewrite</module>, and then

<code>/def</code> to <code>/ghi</code> using

<module>mod_alias</module>:

<example>

RewriteRule ^/abc(.*) /def$1 [PT]<br />

Alias /def /ghi

</example>

If you omit the <code>PT</code> flag,

<module>mod_rewrite</module> will rewrite

<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> will try to do a

URI-to-filename transition, which will fail.

<p>Note: <strong>You must use this flag if you want to

mix directives from different modules which allow

URL-to-filename translators</strong>. The typical example

is the use of <module>mod_alias</module> and

<module>mod_rewrite</module>.</p>

<p>The <code>PT</code> flag implies the <code>L</code> flag:

rewriting will be stopped in order to pass the request to

the next phase of processing.</p>

</dd>

<dt>'<code>qsappend|QSA</code>'

(query string

append)</dt><dd>

This flag forces the rewrite engine to append a query

string part of the substitution string to the existing string,

instead of replacing it. Use this when you want to add more

data to the query string via a rewrite rule.</dd>

<dt>'<code>redirect|R</code>

[=<em>code</em>]' (force <a id="redirect"

name="redirect">redirect</a>)</dt><dd>

<p>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) will be returned. If you want to use other

response codes, simply specify the appropriate number or use

one of the following symbolic names: <code>temp</code>

(default), <code>permanent</code>,

<code>seeother</code>. Use this for rules to canonicalize

the URL and return it to the client - to translate

``<code>/~</code>'' into ``<code>/u/</code>'', or to always

append a slash to <code>/u/</code><em>user</em>, etc.<br />

<strong>Note:</strong> When you use this flag, make sure

that the substitution field is a valid URL! Otherwise, you

will be redirecting to an invalid location. Remember that

this flag on its own will only prepend

<code>http://thishost[:thisport]/</code> to the URL, and

rewriting will continue. Usually, you will want to stop

rewriting at this point, and redirect immediately. To stop

rewriting, you should add the 'L' flag.</p>

<p>While this is typically used for redirects, any valid status

code can be given here. If the status code is outside the redirect

range (300-399), then the <em>Substitution</em> string is dropped

and rewriting is stopped as if the <code>L</code> flag was

used.</p>

</dd>

<dt>'<code>skip|S</code>=<em>num</em>'

(skip next rule(s))</dt><dd>

This flag forces the rewriting engine to skip the next

<em>num</em> rules in sequence, if the current rule

matches. Use this to make pseudo if-then-else constructs:

The last rule of the then-clause becomes

<code>skip=N</code>, where N is the number of rules in the

else-clause. (This is <strong>not</strong> the same as the

'chain|C' flag!)</dd>

<dt>

'<code>type|T</code>=<em>MIME-type</em>'

(force MIME type)</dt><dd>

Force the <glossary>MIME-type</glossary> of the target file to be

<em>MIME-type</em>. This can be used to

set up the content-type based on some conditions.

If used in per-directory context, use only <code>-</code> (dash)

as the substitution, otherwise the MIME-type set with this flag

is lost due to an internal re-processing.</dd>

</dl>

<note><title>Home directory expansion</title>

<p> When the substitution string begins with a string

resembling "/~user" (via explicit text or backreferences), mod_rewrite performs

home directory expansion independent of the presence or configuration

of <module>mod_userdir</module>.</p>

<p> This expansion does not occur when the <em>PT</em>

flag is used on the <directive module="mod_rewrite">RewriteRule</directive>

directive.</p>

</note>

<note><title>Per-directory Rewrites</title>

<p>The rewrite engine may be used in <a

href="/howto/htaccess.html">.htaccess</a> files. To enable the

rewrite engine for these files you need to set

"<code>RewriteEngine On</code>" <strong>and</strong>

"<code>Options FollowSymLinks</code>" must be enabled. If your

administrator has disabled override of <code>FollowSymLinks</code> for

a user's directory, then you cannot use the rewrite engine. This

restriction is required for security reasons.</p>

<p>When using the rewrite engine in <code>.htaccess</code> files the

per-directory prefix (which always is the same for a specific

directory) is automatically <em>removed</em> for the pattern matching

and automatically <em>added</em> after the substitution has been

done. This feature is essential for many sorts of rewriting; without

this, you would always have to match the parent directory, which is

not always possible. There is one exception: If a substitution string

starts with <code>http://</code>, then the directory prefix will

<strong>not</strong> be added, and an external redirect (or proxy

throughput, if using flag <strong>P</strong>) is forced. See the

<directive module="mod_rewrite">RewriteBase</directive> directive for

more information.</p>

<p>The rewrite engine may also be used in <directive type="section"

module="core">Directory</directive> sections with the same

prefix-matching rules as would be applied to <code>.htaccess</code>

files. It is usually simpler, however, to avoid the prefix substitution

complication by putting the rewrite rules in the main server or

virtual host context, rather than in a <directive type="section"

module="core">Directory</directive> section.</p>

<p>Although rewrite rules are syntactically permitted in <directive

type="section" module="core">Location</directive> and <directive

type="section" module="core">Files</directive> sections, this