Google Git Google Git
Sign in
apache/httpd/refs/heads/docs-modern-css/./docs/manual/mod/mod_rewrite.xml
blob: 14c8b621a18317eced86bf4495bd66daa93b28ab [file]
<?xml version="1.0"?>
<!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
<?xml-stylesheet type="text/xsl" href="../style/manual.en.xsl"?>
<!-- $LastChangedRevision$ -->
<!--
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements. See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<modulesynopsis metafile="mod_rewrite.xml.meta">
<name>mod_rewrite</name>
<description>Provides a rule-based rewriting engine to rewrite requested
URLs on the fly</description>
<status>Extension</status>
<sourcefile>mod_rewrite.c</sourcefile>
<identifier>rewrite_module</identifier>
<summary>
<p>The <module>mod_rewrite</module> module uses a rule-based rewriting
engine, based on a PCRE regular-expression parser, to rewrite requested URLs on
the fly. By default, <module>mod_rewrite</module> maps a URL to a filesystem
path. However, it can also be used to redirect one URL to another URL, or
to invoke an internal proxy fetch.</p>
<p>It provides a flexible and powerful way to manipulate URLs using an
unlimited number of rules. Each rule can have an
unlimited number of attached rule conditions, to allow you to rewrite URLs
based on <a href="#rewritecond">server variables</a> (including HTTP
headers, connection details, and timestamps), environment variables,
or other request properties. Rules can operate on the
<a href="directive-dict.html#Syntax">URL-path</a> (including any
<a href="core.html#acceptpathinfo">trailing pathname information</a>)
and can also alter the
<a href="../expr.html#vars">query string</a>.</p>
<p>A rewrite rule
can be invoked in the server configuration files, or in <glossary
ref="perdirectory">per-directory</glossary> context. The substitution
string of a rewrite rule can include a query string, and a rule can lead to internal
sub-processing, external request redirection, or internal proxy
throughput.</p>
<p>Further details, discussion, and examples, are provided in the
detailed <a href="../rewrite/">Guide to mod_rewrite</a>.</p>
</summary>
<seealso><a href="../rewrite/">Guide to mod_rewrite</a></seealso>
<section id="logging"><title>Logging</title>
<p><module>mod_rewrite</module> offers detailed logging of its actions
at the <code>trace1</code> to <code>trace8</code> log levels. The
log level can be set specifically for <module>mod_rewrite</module>
using the <directive module="core">LogLevel</directive> directive: Up to
level <code>debug</code>, no actions are logged, while <code>trace8</code>
means that practically all actions are logged.</p>
<note>
Using a high trace log level for <module>mod_rewrite</module>
will slow down your Apache HTTP Server dramatically! Use a log
level higher than <code>trace2</code> only for debugging!
</note>
<example><title>Example</title>
<highlight language="config">
LogLevel alert rewrite:trace3
</highlight>
</example>
<note><title>RewriteLog</title>
<p>Those familiar with earlier versions of
<module>mod_rewrite</module> will no doubt be looking for the
<code>RewriteLog</code> and <code>RewriteLogLevel</code>
directives. Since the release of httpd 2.4, these directives
have been replaced with the per-module logging configuration
provided by <directive module="core">LogLevel</directive>.
</p>
<p>To get just the <module>mod_rewrite</module>-specific log
messages, pipe the log file through grep:</p>
<example>
<highlight language="sh">
tail -f error_log|fgrep '[rewrite:'
</highlight>
</example>
</note>
</section>
<directivesynopsis>
<name>RewriteEngine</name>
<description>Enables or disables runtime rewriting engine</description>
<syntax>RewriteEngine on|off</syntax>
<default>RewriteEngine off</default>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context></contextlist>
<override>FileInfo</override>
<usage>
<p>The <directive>RewriteEngine</directive> 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 rules in a particular context,
rather than commenting out all the <directive
module="mod_rewrite">RewriteRule</directive> directives.</p>
<p>Note that rewrite configurations are not
inherited by virtual hosts. This means that you need to have a
<code>RewriteEngine on</code> directive for each virtual host
in which you wish to use rewrite rules.</p>
<p><directive module="mod_rewrite">RewriteMap</directive> directives
of the type <code>prg</code>
are not started during server initialization if they're defined in a
context that does not have <directive>RewriteEngine</directive> set to
<code>on</code></p>
</usage>
</directivesynopsis>
<directivesynopsis>
<name>RewriteOptions</name>
<description>Sets some special options for the rewrite engine</description>
<syntax>RewriteOptions <var>Options</var></syntax>
<contextlist><context>server config</context><context>virtual host</context>
<context>directory</context><context>.htaccess</context></contextlist>
<override>FileInfo</override>
<usage>
<p>The <directive>RewriteOptions</directive> directive sets some
special options for the current per-server or per-directory
configuration. The <em>Option</em> string can currently
only be one of the following:</p>
<dl>
<dt><code>Inherit</code></dt>
<dd>
<p>This forces the current configuration to inherit the
configuration of the parent. In per-virtual-server context,
this means that the maps, conditions and rules of the main
server are inherited. In per-directory context this means
that conditions and rules of the parent directory's
<code>.htaccess</code> configuration or
<directive type="section" module="core">Directory</directive>
sections are inherited. The inherited rules are virtually copied
to the section where this directive is being used. If used in
combination with local rules, the inherited rules are copied behind
the local rules. The position of this directive - below or above
of local rules - has no influence on this behavior. If local
rules forced the rewriting to stop, the inherited rules won't
be processed.</p>
<note type="warning">
Rules inherited from the parent scope are applied
<strong>after</strong> rules specified in the child scope.
</note>
</dd>
<dt><code>InheritBefore</code></dt>
<dd>
<p> Like <code>Inherit</code> above, but the rules from the parent scope
are applied <strong>before</strong> rules specified in the child scope.<br />
Available in Apache HTTP Server 2.3.10 and later.</p>
</dd>
<dt><code>InheritDown</code></dt>
<dd>
<p>If this option is enabled, all child configurations will inherit
the configuration of the current configuration. It is equivalent to
specifying <code>RewriteOptions Inherit</code> in all child
configurations. See the <code>Inherit</code> option for more details
on how the parent-child relationships are handled.<br />
Available in Apache HTTP Server 2.4.8 and later.</p>
</dd>
<dt><code>InheritDownBefore</code></dt>
<dd>
<p>Like <code>InheritDown</code> above, but the rules from the current
scope are applied <strong>before</strong> rules specified in any child's
scope.<br />
Available in Apache HTTP Server 2.4.8 and later.</p>
</dd>
<dt><code>IgnoreInherit</code></dt>
<dd>
<p>This option forces the current and child configurations to ignore
all rules that would be inherited from a parent specifying
<code>InheritDown</code> or <code>InheritDownBefore</code>.<br />
Available in Apache HTTP Server 2.4.8 and later.</p>
</dd>
<dt><code>AllowNoSlash</code></dt>
<dd>
<p>By default, <module>mod_rewrite</module> will ignore URLs that map to a
directory on disk but lack a trailing slash, in the expectation that
the <module>mod_dir</module> module will issue the client with a redirect to
the canonical URL with a trailing slash.</p>
<p>When the <directive module="mod_dir">DirectorySlash</directive> directive
is set to off, the <code>AllowNoSlash</code> option can be enabled to ensure
that rewrite rules are no longer ignored. This option makes it possible to
apply rewrite rules within .htaccess files that match the directory without
a trailing slash, if so desired.<br />
Available in Apache HTTP Server 2.4.0 and later.</p>
</dd>
<dt><code>AllowAnyURI</code></dt>
<dd>
<p>When <directive module="mod_rewrite">RewriteRule</directive>
is used in <code>VirtualHost</code> or server context with
version 2.2.22 or later of httpd, <module>mod_rewrite</module>
will only process the rewrite rules if the request URI is a <a
href="directive-dict.html#Syntax">URL-path</a>. This avoids
some security issues where particular rules could allow
"surprising" pattern expansions (see <a
href="http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-3368">CVE-2011-3368</a>
and <a
href="http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-4317">CVE-2011-4317</a>).
To lift the restriction on matching a URL-path, the
<code>AllowAnyURI</code> option can be enabled, and
<module>mod_rewrite</module> will apply the rule set to any
request URI string, regardless of whether that string matches
the URL-path grammar required by the HTTP specification.<br />
Available in Apache HTTP Server 2.4.3 and later.</p>
<note type="warning">
<title>Security Warning</title>
<p>Enabling this option will make the server vulnerable to
security issues if used with rewrite rules which are not
carefully authored. It is <strong>strongly recommended</strong>
that this option is not used. In particular, beware of input
strings containing the '<code>@</code>' character which could
change the interpretation of the transformed URI, as per the
above CVE names.</p>
</note>
</dd>
<dt><code>MergeBase</code></dt>
<dd>
<p>With this option, the value of <directive module="mod_rewrite"
>RewriteBase</directive> is copied from where it's explicitly defined
into any sub-directory or sub-location that doesn't define its own
<directive module="mod_rewrite">RewriteBase</directive>. This was the
default behavior in 2.4.0 through 2.4.3, and the flag to restore it is
available Apache HTTP Server 2.4.4 and later.</p>
</dd>
<dt><code>IgnoreContextInfo</code></dt>
<dd>
<p>When a relative substitution is made
in directory (htaccess) context and <directive module="mod_rewrite"
>RewriteBase</directive> has not been set, this module uses some
extended URL and filesystem context information to change the
relative substitution back into a URL. Modules such as
<module>mod_userdir</module> and <module>mod_alias</module>
supply this extended context info. Available in 2.4.16 and later.</p>
</dd>
<dt><code>LegacyPrefixDocRoot</code></dt>
<dd>
<p>Prior to 2.4.26, if a substitution was an absolute URL that matched
the current virtual host, the URL might first be reduced to a URL-path
and then later reduced to a local path. Since the URL can be reduced
to a local path, the path should be prefixed with the document root.
This prevents a file such as /tmp/myfile from being accessed when a
request is made to http://host/file/myfile with the following
<directive module="mod_rewrite">RewriteRule</directive>.</p>
<highlight language="config">
RewriteRule /file/(.*) http://localhost/tmp/$1
</highlight>
<p>This option allows the old behavior to be used where the document
root is not prefixed to a local path that was reduced from a
URL. Available in 2.4.26 and later.</p>
</dd>
<dt><code>LongURLOptimization</code></dt>
<dd>
<p>This option reduces memory usage of long, unoptimized rule sets
that repeatedly expand long values in RewriteCond and RewriteRule
variables. Available in 2.5 and later.</p>
</dd>
</dl>
</usage>
</directivesynopsis>
<directivesynopsis>
<name>RewriteMap</name>
<description>Defines a mapping function for key-lookup</description>
<syntax>RewriteMap <em>MapName</em> <em>MapType</em>:<em>MapSource</em>
[<em>MapTypeOptions</em>]
</syntax>
<contextlist><context>server config</context><context>virtual host</context>
</contextlist>
<compatibility>The 3rd parameter, MapTypeOptions, is only available in Apache httpd
2.4.29 and later.</compatibility>
<usage>
<p>The <directive>RewriteMap</directive> directive defines a
<em>Rewriting Map</em> which can be used inside rule
substitution strings by the mapping-functions to
insert/substitute fields through a key lookup. The source of
this lookup can be of various types.</p>
<p>The <a id="mapfunc" name="mapfunc"><em>MapName</em></a> is
the name of the map and will be used to specify a
mapping-function for the substitution strings of a rewriting
rule via one of the following constructs:</p>
<p class="indent">
<strong><code>${</code> <em>MapName</em> <code>:</code>
<em>LookupKey</em> <code>}</code><br />
<code>${</code> <em>MapName</em> <code>:</code>
<em>LookupKey</em> <code>|</code> <em>DefaultValue</em>
<code>}</code></strong>
</p>
<p>When such a construct occurs, the map <em>MapName</em> is
consulted and the key <em>LookupKey</em> is looked-up. If the
key is found, the map-function construct is substituted by
<em>SubstValue</em>. If the key is not found then it is
substituted by <em>DefaultValue</em> or by the empty string
if no <em>DefaultValue</em> was specified. Empty values
behave as if the key was absent, therefore it is not possible
to distinguish between empty-valued keys and absent keys.</p>
<p>For example, you might define a
<directive>RewriteMap</directive> as:</p>
<highlight language="config">
RewriteMap examplemap "txt:/path/to/file/map.txt"
</highlight>
<p>You would then be able to use this map in a
<directive module="mod_rewrite">RewriteRule</directive> as follows:</p>
<highlight language="config">
RewriteRule "^/ex/(.*)" "${examplemap:$1}"
</highlight>
<p>The meaning of the <em>MapTypeOptions</em> argument depends on
particular <em>MapType</em>. See the
<a href="../rewrite/rewritemap.html">Using RewriteMap</a> for
more information.</p>
<p>The following combinations for <em>MapType</em> and
<em>MapSource</em> can be used:</p>
<dl>
<dt>txt</dt>
<dd>A plain text file containing space-separated key-value
pairs, one per line. (<a href="../rewrite/rewritemap.html#txt">Details ...</a>)</dd>
<dt>rnd</dt>
<dd>Randomly selects an entry from a plain text file (<a href="../rewrite/rewritemap.html#rnd">Details ...</a>)</dd>
<dt>dbm</dt>
<dd>Looks up an entry in a dbm file containing name, value
pairs. Hash is constructed from a plain text file format using
the <code><a href="../programs/httxt2dbm.html">httxt2dbm</a></code>
utility. (<a href="../rewrite/rewritemap.html#dbm">Details ...</a>)</dd>
<dt>int</dt>
<dd>One of the four available internal functions provided by
<code>RewriteMap</code>: toupper, tolower, escape or
unescape. (<a href="../rewrite/rewritemap.html#int">Details ...</a>)</dd>
<dt>prg</dt>
<dd>Calls an external program or script to process the
rewriting. (<a href="../rewrite/rewritemap.html#prg">Details ...</a>)</dd>
<dt>dbd or fastdbd</dt>
<dd>A SQL SELECT statement to be performed to look up the
rewrite target. (<a href="../rewrite/rewritemap.html#dbd">Details ...</a>)</dd>
</dl>
<p>Further details, and numerous examples, may be found in the <a
href="../rewrite/rewritemap.html">RewriteMap HowTo</a></p>
</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 specifies the
URL prefix to be used for
<glossary ref="perdirectory">per-directory</glossary>
<directive module="mod_rewrite">RewriteRule</directive> directives that
substitute a relative path.</p>
<p> This directive is <em>required</em> when you use a relative path
in a substitution in <glossary ref="perdirectory">per-directory</glossary> context unless any
of the following conditions are true:</p>
<ul>
<li> The original request, and the substitution, are underneath the
<directive module="core">DocumentRoot</directive>
(as opposed to reachable by other means, such as
<directive module="mod_alias">Alias</directive>).</li>
<li> The directory-path for which the RewriteRule applies,
suffixed by the relative substitution, is also valid
as a URL-path on the server (this is rare).</li>
<li> In Apache HTTP Server 2.4.16 and later, this directive may be
omitted when the request is mapped via
<directive module="mod_alias">Alias</directive>
or <module>mod_userdir</module>.</li>
</ul>
</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> [<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>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>If the <em>CondPattern</em> is prefixed with a <code>!</code> the
condition is determined to be true only if the
<em>CondPattern</em> does not match.</p>
<!-- ============================================================ -->
<!-- TestString -->
<!-- ============================================================ -->
<p><a id="rewritecond-teststring" name="rewritecond-teststring"
></a><strong>TestString</strong></p>
<p><em>TestString</em> is a string which can contain the
following expanded constructs in addition to plain text:</p>
<!-- Backreferences -->
<p><a id="rewritecond-backreferences" name="rewritecond-backreferences"
></a><strong>Backreferences</strong></p>
<dl>
<dt><strong><code>$N</code></strong> &mdash; RewriteRule backreferences</dt>
<dd>Backreferences of the form <code>$N</code>
(0 &lt;= N &lt;= 9). $1 to $9 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. $0 provides
access to the whole string matched by that pattern.</dd>
<dt><strong><code>%N</code></strong> &mdash; RewriteCond backreferences</dt>
<dd>Backreferences of the form <code>%N</code>
(0 &lt;= N &lt;= 9). %1 to %9 provide access to the grouped
parts (again, in parentheses) of the pattern, from the last matched
<code>RewriteCond</code> in the current set
of conditions. %0 provides access to the whole string matched by
that pattern.</dd>
</dl>
<note>Backreferences are only defined if the pattern
matches. Thus, if the pattern is prefixed with
<code>!</code>, no backreferences are ever defined.
See <a href="../rewrite/tech.html#InternalRuleset">How the
Ruleset is Applied</a> for more details on the order in which
patterns are matched and backreferences populated.</note>
<!-- RewriteMap Expansions -->
<p><a id="rewritecond-mapexpansions" name="rewritecond-mapexpansions"
></a><strong>RewriteMap Expansions</strong></p>
<p>These are expansions of the form <strong><code
>${mapname:key|default}</code></strong>.
See <a href="#mapfunc">the documentation for
RewriteMap</a> for more details.</p>
<!-- Server and CGI Variables -->
<p><a id="rewritecond-servervars" name="rewritecond-servervars"
></a><strong>Server and CGI Variables</strong></p>
<p>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:</p>
<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_ACCEPT<br />
HTTP_COOKIE<br />
HTTP_FORWARDED<br />
HTTP_HOST<br />
HTTP_PROXY_CONNECTION<br />
HTTP_REFERER<br />
HTTP_USER_AGENT<br />
</td>
<td>
AUTH_TYPE<br />
CONN_REMOTE_ADDR<br />
CONTEXT_PREFIX<br />
CONTEXT_DOCUMENT_ROOT<br />
IPV6<br />
<glossary ref="pathinfo">PATH_INFO</glossary><br />
QUERY_STRING<br />
REMOTE_ADDR<br />
REMOTE_HOST<br />
REMOTE_IDENT<br />
REMOTE_PORT<br />
REMOTE_USER<br />
REQUEST_METHOD<br />
SCRIPT_FILENAME<br />
</td>
<td></td>
</tr>
<tr>
<th>server internals:</th> <th>date and time:</th> <th>specials:</th>
</tr>
<tr>
<td>
DOCUMENT_ROOT<br />
SCRIPT_GROUP<br />
SCRIPT_USER<br />
SERVER_ADDR<br />
SERVER_ADMIN<br />
SERVER_NAME<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 />
CONN_REMOTE_ADDR<br />
HTTPS<br />
IS_SUBREQ<br />
REMOTE_ADDR<br />
REQUEST_FILENAME<br />
REQUEST_SCHEME<br />
REQUEST_URI<br />
THE_REQUEST<br />
</td>
</tr>
</table>
<p>These variables all
correspond to the similarly named HTTP
MIME-headers, C variables of the Apache HTTP Server or
<code>struct tm</code> fields of the Unix system.
Most are documented in the
<a href="../expr.html#vars">Expressions doc</a>, in the
<a href="../env.html">Environment Variables doc</a>,
or the CGI specification (<rfc>3875</rfc>).</p>
<p>SERVER_NAME and SERVER_PORT depend on the values of
<directive module="core">UseCanonicalName</directive> and
<directive module="core">UseCanonicalPhysicalPort</directive>
respectively.</p>
<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 HTTP 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>
<p>Those that are special to <module>mod_rewrite</module>
include those below.</p>
<dl>
<dt><code>API_VERSION</code></dt>
<dd>This is the version of the Apache httpd 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 httpd in use (in
the release version of Apache httpd 1.3.14, for
instance, it is 19990320:10), but is mainly of
interest to module authors.</dd>
<dt><code>CONN_REMOTE_ADDR</code></dt>
<dd>Since 2.4.8: The peer IP address of the connection (see the
<module>mod_remoteip</module> module).</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>
<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>REMOTE_ADDR</code></dt>
<dd>The IP address of the remote host (see the
<module>mod_remoteip</module> module).</dd>
<dt><code>REQUEST_FILENAME</code></dt>
<dd>The full local filesystem path to the file or
script matching the request, if this has already
been determined by the server at the time
<code>REQUEST_FILENAME</code> is referenced. Otherwise,
such as when used in virtual host context, the same
value as <code>REQUEST_URI</code>. Depending on the value of
<directive module="core">AcceptPathInfo</directive>, the
server may have only used some leading components of the
<code>REQUEST_URI</code> to map the request to a file.
</dd>
<dt><code>REQUEST_SCHEME</code></dt>
<dd>Will contain the scheme of the request (usually
"http" or "https"). This value can be influenced with
<directive module="core">ServerName</directive>.</dd>
<dt><code>REQUEST_URI</code></dt>
<dd>The path component of the requested URI,
such as "/index.html". This notably excludes the
query string which is available as its own variable
named <code>QUERY_STRING</code>. The value returned for
<code>REQUEST_URI</code>
has already been %-decoded, to re-encode it pass it through
the "escape" <a href="#mapfunc">mapping-function</a>.
Note that this server variable differs from the CGI
environment variable of the same name: in a CGI context,
<code>REQUEST_URI</code> contains the full original URI
from the request line, including the query string. See
the <directive module="core">CGIVar</directive>
directive for details.
</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. This value has not been unescaped
(decoded), unlike most other variables below.</dd>
</dl>
<!-- Prefixed Variable Lookups -->
<p><a id="rewritecond-prefixed" name="rewritecond-prefixed"
></a><strong>Prefixed Variable Lookups</strong></p>
<p>In addition to the server variables above, the
<code>%{<em>PREFIX</em>:<em>name</em>}</code> syntax provides
access to additional sources:</p>
<dl>
<dt><strong><code>%{ENV:variable}</code></strong></dt>
<dd>Where <em>variable</em> can be
any environment variable. This is looked-up via internal
Apache httpd structures and (if not found there) via
<code>getenv()</code> from the Apache httpd server process.</dd>
<dt><strong><code>%{SSL:variable}</code></strong></dt>
<dd>Where <em>variable</em> is the
name of an <a href="mod_ssl.html#envvars">SSL environment
variable</a>. This 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>. These variables are available even without
setting the <code>StdEnvVars</code> option of the
<directive module="mod_ssl">SSLOptions</directive> directive.</dd>
<dt><strong><code>%{HTTP:header}</code></strong></dt>
<dd>Where <em>header</em> can be
any HTTP MIME-header name. This 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 an HTTP header is used in a condition, this header is added to
the Vary header of the response in case the condition evaluates
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></dd>
</dl>
<!-- Look-ahead Sub-requests -->
<p><a id="rewritecond-lookahead" name="rewritecond-lookahead"
></a><strong>Look-ahead Sub-requests</strong></p>
<p>These forms perform an internal sub-request to determine the
final value of a variable that is not yet available at the current
stage of processing:</p>
<dl>
<dt><a id="LA-U" name="LA-U"><strong><code>%{LA-U:variable}</code></strong></a></dt>
<dd>Performs an internal (URL-based) sub-request to determine the final
value of <em>variable</em>. This can be used to access
a 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
<module>mod_rewrite</module> operates).</p>
<p>On the other hand, because <module>mod_rewrite</module> implements
its <glossary ref="perdirectory">per-directory</glossary> context 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></dd>
<dt><strong><code>%{LA-F:variable}</code></strong></dt>
<dd>Performs an internal (filename-based) sub-request to determine
the final value of <em>variable</em>. Most of the time, this is
the same as LA-U above.</dd>
</dl>
<!-- Expression Syntax -->
<p><a id="rewritecond-expr" name="rewritecond-expr"
></a><strong>Expression Syntax</strong></p>
<p>If the <em>TestString</em> has the special value <code>expr</code>,
the <em>CondPattern</em> will be treated as an
<a href="../expr.html">ap_expr</a>. HTTP headers referenced in the
expression will be added to the Vary header if the <code>novary</code>
flag is not given.</p>
<!-- ============================================================ -->
<!-- CondPattern -->
<!-- ============================================================ -->
<p><a id="rewritecond-condpattern" name="rewritecond-condpattern"
></a><strong>CondPattern</strong></p>
<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><em>CondPattern</em> is usually a
<glossary ref="regex">regular expression</glossary>, but there is
additional syntax available to perform other useful tests against
the <em>Teststring</em>:</p>
<!-- Negation -->
<p>You can prefix the pattern string with a
'<code>!</code>' character (exclamation mark) to negate the result
of the condition, no matter what kind of <em>CondPattern</em> is used.
</p>
<!-- String Comparisons -->
<p><a id="rewritecond-stringcomp" name="rewritecond-stringcomp"
></a><strong>String Comparisons</strong></p>
<dl>
<dt><strong>&lt;CondPattern</strong></dt>
<dd>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>.</dd>
<dt><strong>&gt;CondPattern</strong></dt>
<dd>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>.</dd>
<dt><strong>=CondPattern</strong></dt>
<dd>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.</dd>
<dt><strong>&lt;=CondPattern</strong></dt>
<dd>Lexicographically less than or equal to<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>, or is equal to <em>CondPattern</em>
(the two strings are equal, character for character).</dd>
<dt><strong>&gt;=CondPattern</strong></dt>
<dd>Lexicographically greater than or equal to<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>, or is equal to <em>CondPattern</em>
(the two strings are equal, character for character).</dd>
</dl>
<note><title>Note</title>
The string comparison operator is part of the <em>CondPattern</em>
argument and must be included in the quotes if those are used. Eg.
<highlight language="config">
RewriteCond %{HTTP_USER_AGENT} "=This Robot/1.0"
</highlight>
</note>
<!-- Integer Comparisons -->
<p><a id="rewritecond-intcomp" name="rewritecond-intcomp"
></a><strong>Integer Comparisons</strong></p>
<dl>
<dt><strong>-eq</strong></dt>
<dd>Is numerically <strong>eq</strong>ual to<br />
The <em>TestString</em> is treated as an integer, and is
numerically compared to the <em>CondPattern</em>. True if
the two are numerically equal.</dd>
<dt><strong>-ge</strong></dt>
<dd>Is numerically <strong>g</strong>reater than or <strong>e</strong>qual to<br />
The <em>TestString</em> is treated as an integer, and is
numerically compared to the <em>CondPattern</em>. True if
the <em>TestString</em> is numerically greater than or equal
to the <em>CondPattern</em>.</dd>
<dt><strong>-gt</strong></dt>
<dd>Is numerically <strong>g</strong>reater <strong>t</strong>han<br />
The <em>TestString</em> is treated as an integer, and is
numerically compared to the <em>CondPattern</em>. True if
the <em>TestString</em> is numerically greater than
the <em>CondPattern</em>.</dd>
<dt><strong>-le</strong></dt>
<dd>Is numerically <strong>l</strong>ess than or <strong>e</strong>qual to<br />
The <em>TestString</em> is treated as an integer, and is
numerically compared to the <em>CondPattern</em>. True if
the <em>TestString</em> is numerically less than or equal
to the <em>CondPattern</em>. Avoid confusion with the
<strong>-l</strong> by using the <strong>-L</strong> or
<strong>-h</strong> variant.</dd>
<dt><strong>-lt</strong></dt>
<dd>Is numerically <strong>l</strong>ess <strong>t</strong>han<br />
The <em>TestString</em> is treated as an integer, and is
numerically compared to the <em>CondPattern</em>. True if
the <em>TestString</em> is numerically less than
the <em>CondPattern</em>. Avoid confusion with the
<strong>-l</strong> by using the <strong>-L</strong> or
<strong>-h</strong> variant.</dd>
<dt><strong>-ne</strong></dt>
<dd>Is numerically <strong>n</strong>ot <strong>e</strong>qual to<br />
The <em>TestString</em> is treated as an integer, and is
numerically compared to the <em>CondPattern</em>. True if
the two are numerically different. This is equivalent to
<code>!-eq</code>.</dd>
</dl>
<!-- File Attribute Tests -->
<p><a id="rewritecond-fileattr" name="rewritecond-fileattr"
></a><strong>File Attribute Tests</strong></p>
<dl>
<dt><strong>-d</strong></dt>
<dd>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.
</dd>
<dt><strong>-f</strong></dt>
<dd>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.
</dd>
<dt><strong>-F</strong></dt>
<dd>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!
</dd>
<dt><strong>-h</strong></dt>
<dd>Is symbolic link, bash convention.<br />
See <strong>-l</strong>.
</dd>
<dt><strong>-l</strong></dt>
<dd>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. May also
use the bash convention of <strong>-L</strong> or
<strong>-h</strong> if there's a possibility of confusion
such as when using the <strong>-lt</strong> or
<strong>-le</strong> tests.
</dd>
<dt><strong>-L</strong></dt>
<dd>Is symbolic link, bash convention.<br />
See <strong>-l</strong>.</dd>
<dt><strong>-s</strong></dt>
<dd>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.</dd>
<dt><strong>-U</strong></dt>
<dd><p>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!</p>
<p> This flag <em>only</em> returns information about things
like access control, authentication, and authorization. This flag
<em>does not</em> return information about the status code the
configured handler (static file, CGI, proxy, etc.) would have
returned.</p> </dd>
<dt><strong>-x</strong></dt>
<dd>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.</dd>
</dl>
<p>For example:</p>
<highlight language="config">
RewriteCond /var/www/%{REQUEST_URI} !-f
RewriteRule ^(.+) /other/archive/$1 [R]
</highlight>
<!-- Expression Evaluation in CondPattern -->
<p><a id="rewritecond-expr-pattern" name="rewritecond-expr-pattern"
></a><strong>Expression Evaluation</strong></p>
<p>If the <em>TestString</em> has the special value <code>expr</code>, the
<em>CondPattern</em> will be treated as an
<a href="../expr.html">ap_expr</a>.</p>
<p>
In the below example, <code>-strmatch</code> is used to
compare the <code>REFERER</code> against the site hostname,
to block unwanted hotlinking.
</p>
<highlight language="config">
RewriteCond expr "! %{HTTP_REFERER} -strmatch '*://%{HTTP_HOST}/*'"
RewriteRule "^/images" "-" [F]
</highlight>
<!-- ============================================================ -->
<!-- Flags -->
<!-- ============================================================ -->
<p><a id="rewritecond-flags" name="rewritecond-flags"
></a><strong>Flags</strong></p>
<p>You can set special flags for <em>CondPattern</em> by appending
<strong><code>[</code><em>flags</em><code>]</code></strong>
as the third argument to the <directive>RewriteCond</directive>
directive, where <em>flags</em> is a comma-separated list of any of the
following flags:</p>
<dl>
<dt>'<strong><code>nocase|NC</code></strong>'</dt>
<dd>(<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.</dd>
<dt>'<strong><code>ornext|OR</code></strong>'</dt>
<dd>(<strong>or</strong> next condition)<br />
Use this to combine rule conditions with a local OR
instead of the implicit AND. Typical example:
<highlight language="config">
RewriteCond "%{REMOTE_HOST}" "^host1" [OR]
RewriteCond "%{REMOTE_HOST}" "^host2" [OR]
RewriteCond "%{REMOTE_HOST}" "^host3"
RewriteRule ...some special stuff for any of these hosts...
</highlight>
Without this flag you would have to write the condition/rule
pair three times.
</dd>
<dt>'<strong><code>novary|NV</code></strong>'</dt>
<dd>(<strong>n</strong>o <strong>v</strong>ary)<br />
If an 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.
</dd>
</dl>
<!-- ============================================================ -->
<!-- Example -->
<!-- ============================================================ -->
<p><a id="rewritecond-examples" name="rewritecond-examples"
></a><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>
<highlight language="config">
RewriteCond "%{HTTP_USER_AGENT}" "(iPhone|Blackberry|Android)"
RewriteRule "^/$" "/homepage.mobile.html" [L]
RewriteRule "^/$" "/homepage.std.html" [L]
</highlight>
<p>Explanation: If you use a browser which identifies itself
as a mobile browser (note that the example is incomplete, as
there are many other mobile platforms), the mobile version of
the homepage is served. Otherwise, the standard page is served.
</p>
<p>By default, multiple <directive>RewriteCond</directive>s
are evaluated in sequence with an implied logical <strong>AND</strong>.
If a condition fails, in the absence of an
<strong><code>OR</code></strong> flag, the entire ruleset is abandoned,
and further conditions are not evaluated.
</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 <a id="regexp" name="regexp"><glossary ref="regex">regular
expression</glossary></a>. What this pattern is compared against varies depending
on where the <directive>RewriteRule</directive> directive is defined. </p>
<p>If the pattern is prefixed with a <code>!</code> the
substitution will be performed only if the
<em>pattern</em> does not match.</p>
<note><title><a id="what_is_matched" name="what_is_matched">What is matched?</a></title>
<ul>
<li><p>In <directive module="core">VirtualHost</directive> context,
The <em>Pattern</em> will initially be matched against the part of the
URL after the hostname and port, and before the query string (e.g. "/app1/index.html").
This is the (%-decoded) <a href="directive-dict.html#Syntax">URL-path</a>.</p></li>
<li><p>In <glossary ref="perdirectory">per-directory context</glossary>
(<directive module="core">Directory</directive> and .htaccess),
the <em>Pattern</em> is matched against only a partial path, for example a request
of "/app1/index.html" may result in comparison against "app1/index.html"
or "index.html" depending on the directory-path for which the
<directive>RewriteRule</directive> applies.</p>
<p>The directory-path to which the rule applies is stripped from the currently mapped
filesystem path before comparison (up to and including a trailing slash).
The net result of this <glossary ref="perdirectory">per-directory</glossary> prefix stripping is that rules in
this context only match against the portion of the currently mapped filesystem path
"below" the directory-path to which the rule applies.</p>
<p>Directives such as <directive module="core"
>DocumentRoot</directive> and <directive module="mod_alias">Alias</directive>, or even the
result of previous <directive>RewriteRule</directive> substitutions, determine
the currently mapped filesystem path.
</p>
</li>
<li><p>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></li>
</ul>
</note>
<note><title><glossary ref="perdirectory">Per-directory</glossary> Rewrites</title>
<ul>
<li>The rewrite engine may be used in <a
href="../howto/htaccess.html">.htaccess</a> files and in <directive type="section"
module="core">Directory</directive> sections, with some additional
complexity.</li>
<li>To enable the rewrite engine in this context, you need to set
<code>RewriteEngine On</code> <strong>and</strong>
at least one of the <code>FollowSymLinks</code> or
<code>SymLinksIfOwnerMatch</code>
<directive module="core">Options</directive> must be enabled. Note
that these options cannot be set in a distributed configuration file
(<code>.htaccess</code>) unless
<directive module="core">AllowOverride</directive> permits it
in the server configuration.</li>
<li>See the <directive module="mod_rewrite">RewriteBase</directive>
directive for more information regarding what prefix will be added back to
relative substitutions.</li>
<li> If you wish to match against the full URL-path in a
<glossary ref="perdirectory">per-directory</glossary> context
RewriteRule, use the <code>%{REQUEST_URI}</code> variable in
a <directive module="mod_rewrite">RewriteCond</directive>.</li>
<li>The removed prefix always ends with a slash, meaning the matching occurs against a string which
<em>never</em> has a leading slash. Therefore, a <em>Pattern</em> with <code>^/</code> never
matches in <glossary ref="perdirectory">per-directory</glossary> context.</li>
<li>Although rewrite rules are syntactically permitted in <directive
type="section" module="core">Location</directive> and <directive
type="section" module="core">Files</directive> sections
(including their regular expression counterparts), this
should never be necessary and is unsupported. A likely feature
to break in these contexts is relative substitutions.</li>
<li>The <directive module="core">If</directive> blocks
follow the rules of the <em>directory</em> context.</li>
<li>By default, mod_rewrite overrides rules when <a href="../sections.html#merging">
merging sections</a> belonging to the same context. The <directive
module="mod_rewrite">RewriteOptions</directive> directive can change this behavior,
for example using the <em>Inherit</em> setting.</li>
<li>The <directive module="mod_rewrite">RewriteOptions</directive> also regulates the
behavior of sections that are stated at the same nesting level of the configuration. In the
following example, by default only the RewriteRules stated in the second
<directive module="core">If</directive> block
are considered, since the first ones are overridden. Using <directive
module="mod_rewrite">RewriteOptions</directive> Inherit forces mod_rewrite to merge the two
sections and consider both set of statements, rather than only the last one.</li>
</ul>
<example>
<highlight language="config">
&lt;If "true"&gt;
# Without RewriteOptions Inherit, this rule is overridden by the next
# section and no redirect will happen for URIs containing 'foo'
RewriteRule foo http://example.com/foo [R]
&lt;/If&gt;
&lt;If "true"&gt;
RewriteRule bar http://example.com/bar [R]
&lt;/If&gt;
</highlight>
</example>
</note>
<p>For information on <glossary ref="regex">regular
expressions</glossary>, including the use of the
<code>!</code> prefix to negate a pattern, see the
<a href="../rewrite/intro.html#regex">Regular Expressions</a>
section of the mod_rewrite introduction.</p>
<p>The <a id="rhs" name="rhs"><em>Substitution</em></a> of a
rewrite rule is the string that replaces the URL-path (see
<a href="#what_is_matched">"What is matched?"</a> above)
when the rule's conditions are met. 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. A substitution beginning with
<code>/</code> is treated as a file-system path only in
server or virtual host context, and only when the first
component of the path exists in the file-system. In
<glossary ref="perdirectory">per-directory context</glossary>,
this guessing does not occur.</dd>
<dt>URL-path</dt>
<dd>A <directive
module="core">DocumentRoot</directive>-relative path to the
resource to be served. In server or virtual host context,
if the first segment of the path exists at the root of the
file-system, the substitution is treated as a file-system
path instead. For example, <code>/www/file.html</code> is
a URL-path unless a directory named <code>www</code> exists
at the root of the file-system. 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><p>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.</p>
<p>Note that a redirect (implicit or not) using an absolute URI
will include the requested query-string, to prevent this see the
<code>[QSD]</code> flag below.</p></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>
<note><title>How path substitutions are interpreted</title>
<p>Whether a path substitution is treated as a file-system path
or a URL-path depends on the context and whether it begins with
a slash:</p>
<ul>
<li><strong>Starts with <code>/</code>, server/vhost context:</strong>
Treated as a file-system path if the first path component exists
on disk; otherwise treated as a URL-path.</li>
<li><strong>Starts with <code>/</code>, <glossary ref="perdirectory">per-directory</glossary> context:</strong>
Always treated as a URL-path. No file-system guessing occurs.</li>
<li><strong>Does not start with <code>/</code> (relative),
server/vhost context:</strong> Treated as a URL-path relative
to the current request URI.</li>
<li><strong>Does not start with <code>/</code> (relative),
<glossary ref="perdirectory">per-directory</glossary> context:</strong> Treated as a URL-path relative
to the directory-path for which the <directive
module="core">Directory</directive> or <code>.htaccess</code>
applies. See <directive>RewriteBase</directive> for controlling
the prefix added to relative substitutions.</li>
</ul>
</note>
<p>In addition to plain text, the <em>Substitution</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). <code>$0</code> refers to the
entire string matched by the <em>Pattern</em>, while
<code>$1</code>..<code>$9</code> refer to the corresponding
captured groups from the matched <em>Pattern</em>.
Similarly, back-references
<code>%0</code>..<code>%9</code> refer to the most recently
matched
<directive module="mod_rewrite">RewriteCond</directive>
<em>CondPattern</em>: <code>%0</code> is the entire match and
<code>%1</code>..<code>%9</code> are the captured groups. The server variables are the same
as for the <em>TestString</em> of a
<directive module="mod_rewrite">RewriteCond</directive>
directive. The mapping-functions come from the
<directive module="mod_rewrite">RewriteMap</directive>
directive and are explained there.
These three types of variables are expanded in the order above.</p>
<p>Rewrite rules are applied to the results of previous rewrite
rules, in the order in which they are defined
in the config file. The URL-path or file-system path (see <a
href="#what_is_matched">"What is matched?"</a>, above) 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 an
<a href="../rewrite/flags.html#flag_l"><code><strong>L</strong></code> flag</a>,
or other flag which implies immediate termination, such as
<code><strong>END</strong></code> or
<code><strong>F</strong></code>.</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 <directive>RewriteRule</directive>
directive. <em>Flags</em> is a comma-separated list, surround by square
brackets, of any of the flags in the following table. More
details, and examples, for each flag, are available in the <a
href="../rewrite/flags.html">Rewrite Flags document</a>.</p>
<table border="1" style="zebra">
<tr><th>Flag and syntax</th>
<th>Function</th>
</tr>
<tr>
<td>B</td>
<td>Escape non-alphanumeric characters in backreferences <em>before</em>
applying the transformation. For similar escaping of server variables, see
the "escape" <a href="#mapfunc">mapping-function</a>.<em><a
href="../rewrite/flags.html#flag_b">details ...</a></em></td>
</tr>
<tr>
<td>BCTLS</td>
<td>Like [B], but only escape control characters and spaces.
<em><a href="../rewrite/flags.html#flag_bctls">details ...</a></em></td>
</tr>
<tr>
<td>BNE</td>
<td>Characters of [B] or [BCTLS] which should <strong>not</strong> be escaped.
<em><a href="../rewrite/flags.html#flag_bne">details ...</a></em></td>
</tr>
<tr>
<td>backrefnoplus|BNP</td>
<td>If backreferences are being escaped, spaces should be escaped to
%20 instead of +. Useful when the backreference will be used in the
path component rather than the query string.<em><a
href="../rewrite/flags.html#flag_bnp">details ...</a></em></td>
</tr>
<tr>
<td>chain|C</td>
<td>Rule is chained to the following rule. If the rule fails,
the rule(s) chained to it will be skipped. <em><a
href="../rewrite/flags.html#flag_c">details ...</a></em></td>
</tr>
<tr>
<td>cookie|CO=<em>NAME</em>:<em>VAL</em></td>
<td>Sets a cookie in the client browser. Full syntax is:
CO=<em>NAME</em>:<em>VAL</em>:<em>domain</em>[:<em>lifetime</em>[:<em>path</em>[:<em>secure</em>[:<em>httponly</em>[<em>samesite</em>]]]]] <em><a href="../rewrite/flags.html#flag_co">details ...</a></em>
</td>
</tr>
<tr>
<td>discardpath|DPI</td>
<td>Causes the PATH_INFO portion of the rewritten URI to be
discarded. <em><a href="../rewrite/flags.html#flag_dpi">details
...</a></em></td>
</tr>
<tr>
<td>END</td>
<td>Stop the rewriting process immediately and don't apply any
more rules. Also prevents further execution of rewrite rules
in <glossary ref="perdirectory">per-directory</glossary> context. (Available in 2.3.9 and later)
<em><a href="../rewrite/flags.html#flag_end">details ...</a></em></td>
</tr>
<tr>
<td>env|E=[!]<em>VAR</em>[:<em>VAL</em>]</td>
<td>Causes an environment variable <em>VAR</em> to be set (to the
value <em>VAL</em> if provided). The form !<em>VAR</em> causes
the environment variable <em>VAR</em> to be unset.
<em><a href="../rewrite/flags.html#flag_e">details ...</a></em></td>
</tr>
<tr>
<td>forbidden|F</td>
<td>Returns a 403 FORBIDDEN response to the client browser.
<em><a href="../rewrite/flags.html#flag_f">details ...</a></em></td>
</tr>
<tr>
<td>gone|G</td>
<td>Returns a 410 GONE response to the client browser. <em><a
href="../rewrite/flags.html#flag_g">details ...</a></em></td>
</tr>
<tr>
<td>Handler|H=<em>Content-handler</em></td>
<td>Causes the resulting URI to be sent to the specified
<em>Content-handler</em> for processing. <em><a
href="../rewrite/flags.html#flag_h">details ...</a></em></td>
</tr>
<tr>
<td>last|L</td>
<td>Stop the rewriting process immediately and don't apply any
more rules. Especially note caveats for <glossary ref="perdirectory">per-directory</glossary> context (see also the END flag). <em><a
href="../rewrite/flags.html#flag_l">details ...</a></em></td>
</tr>
<tr>
<td>next|N</td>
<td>Re-run the rewriting process, starting again with the first
rule, using the result of the ruleset so far as a starting
point. <em><a href="../rewrite/flags.html#flag_n">details
...</a></em></td>
</tr>
<tr>
<td>nocase|NC</td>
<td>Makes the pattern comparison case-insensitive.
<em><a href="../rewrite/flags.html#flag_nc">details ...</a></em></td>
</tr>
<tr>
<td>noescape|NE</td>
<td>Prevent mod_rewrite from applying hexcode escaping of
special characters in the result of rewrites that result in
redirection. <em>
<a href="../rewrite/flags.html#flag_ne">details ...</a></em></td>
</tr>
<tr>
<td>nosubreq|NS</td>
<td>Causes a rule to be skipped if the current request is an
internal sub-request. <em><a
href="../rewrite/flags.html#flag_ns">details ...</a></em></td>
</tr>
<tr>
<td>proxy|P</td>
<td>Force the substitution URL to be internally sent as a proxy
request. <em><a href="../rewrite/flags.html#flag_p">details
...</a></em></td>
</tr>
<tr>
<td>passthrough|PT</td>
<td>Forces the resulting URI to be passed back to the URL
mapping engine for processing of other URI-to-filename
translators, such as <code>Alias</code> or
<code>Redirect</code>. <em><a
href="../rewrite/flags.html#flag_pt">details ...</a></em></td>
</tr>
<tr>
<td>qsappend|QSA</td>
<td>Appends any query string from the original request URL to
any query string created in the rewrite target.<em><a
href="../rewrite/flags.html#flag_qsa">details ...</a></em></td>
</tr>
<tr>
<td>qsdiscard|QSD</td>
<td>Discard any query string attached to the incoming URI.
<em><a href="../rewrite/flags.html#flag_qsd">details
...</a></em></td>
</tr>
<tr>
<td>qslast|QSL</td>
<td>Interpret the last (right-most) question mark as the query string
delimiter, instead of the first (left-most) as normally used.
Available in 2.4.19 and later.
<em><a href="../rewrite/flags.html#flag_qsl">details
...</a></em></td>
</tr>
<tr>
<td>redirect|R[=<em>code</em>]</td>
<td>Forces an external redirect, optionally with the specified
HTTP status code. <em><a
href="../rewrite/flags.html#flag_r">details ...</a></em>
</td>
</tr>
<tr>
<td>skip|S=<em>num</em></td>
<td>Tells the rewriting engine to skip the next <em>num</em>
rules if the current rule matches. <em><a
href="../rewrite/flags.html#flag_s">details ...</a></em></td>
</tr>
<tr>
<td>type|T=<em>MIME-type</em></td>
<td>Force the <glossary>MIME-type</glossary> of the target file
to be the specified type. <em><a
href="../rewrite/flags.html#flag_t">details ...</a></em></td>
</tr>
<tr>
<td>UnsafeAllow3F</td>
<td>Allows substitutions from URL's that may be unsafe.
<em><a href="../rewrite/flags.html#flag_unsafe_allow_3f">details ...</a></em>
</td>
</tr>
<tr>
<td>UnsafePrefixStat</td>
<td>Allows potentially unsafe substitutions from a leading variable or backreference to a filesystem path.
<em><a href="../rewrite/flags.html#flag_unsafe_prefix_stat">details ...</a></em><br />
<since>2.5.1</since>
</td>
</tr>
<tr>
<td>UNC</td>
<td>Prevents the merging of multiple leading slashes, as used by Windows UNC paths.
<em><a href="../rewrite/flags.html#flag_unc">details ...</a></em><br />
<since>2.5.1</since>
</td>
</tr>
</table>
<note><title>Home directory expansion</title>
<p> When the substitution string begins with a string
resembling "/~user" (via explicit text or backreferences), <module>mod_rewrite</module> 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>
<p>Here are the possible combinations of substitution string
form, context, and the [R] and [P] flags, and their
meanings:</p>
<p><strong>Outside <glossary ref="perdirectory">per-directory</glossary> configuration<br />
for request ``<code>GET
/somepath/pathinfo</code>'':</strong><br />
</p>
<table border="1" style="zebra">
<tr>
<th>Given Rule</th>
<th>Resulting Substitution</th>
</tr>
<tr>
<td>^/somepath(.*) otherpath$1</td>
<td>invalid, not supported</td>
</tr>
<tr>
<td>^/somepath(.*) otherpath$1 [R]</td>
<td>invalid, not supported</td>
</tr>
<tr>
<td>^/somepath(.*) otherpath$1 [P]</td>
<td>invalid, not supported</td>
</tr>
<tr>
<td>^/somepath(.*) /otherpath$1</td>
<td>/otherpath/pathinfo</td>
</tr>
<tr>
<td>^/somepath(.*) /otherpath$1 [R]</td>
<td>http://thishost/otherpath/pathinfo via external redirection</td>
</tr>
<tr>
<td>^/somepath(.*) /otherpath$1 [P]</td>
<td>doesn't make sense, not supported</td>
</tr>
<tr>
<td>^/somepath(.*) http://thishost/otherpath$1</td>
<td>/otherpath/pathinfo</td>
</tr>
<tr>
<td>^/somepath(.*) http://thishost/otherpath$1 [R]</td>
<td>http://thishost/otherpath/pathinfo via external redirection</td>
</tr>
<tr>
<td>^/somepath(.*) http://thishost/otherpath$1 [P]</td>
<td>doesn't make sense, not supported</td>
</tr>
<tr>
<td>^/somepath(.*) http://otherhost/otherpath$1</td>
<td>http://otherhost/otherpath/pathinfo via external redirection</td>
</tr>
<tr>
<td>^/somepath(.*) http://otherhost/otherpath$1 [R]</td>
<td>http://otherhost/otherpath/pathinfo via external redirection (the [R] flag is redundant)</td>
</tr>
<tr>
<td>^/somepath(.*) http://otherhost/otherpath$1 [P]</td>
<td>http://otherhost/otherpath/pathinfo via internal proxy</td>
</tr>
</table>
<p><strong>Inside <glossary ref="perdirectory">per-directory</glossary> configuration for
<code>/somepath</code><br />
(e.g., <code>.htaccess</code> or <code>&lt;Directory&gt;</code>, with
<code>RewriteBase "/somepath"</code>)<br />
for request ``<code>GET
/somepath/localpath/pathinfo</code>'':</strong><br />
</p>
<table border="1" style="zebra">
<tr>
<th>Given Rule</th>
<th>Resulting Substitution</th>
</tr>
<tr>
<td>^localpath(.*) otherpath$1</td>
<td>/somepath/otherpath/pathinfo</td>
</tr>
<tr>
<td>^localpath(.*) otherpath$1 [R]</td>
<td>http://thishost/somepath/otherpath/pathinfo via external
redirection</td>
</tr>
<tr>
<td>^localpath(.*) otherpath$1 [P]</td>
<td>doesn't make sense, not supported</td>
</tr>
<tr>
<td>^localpath(.*) /otherpath$1</td>
<td>/otherpath/pathinfo</td>
</tr>
<tr>
<td>^localpath(.*) /otherpath$1 [R]</td>
<td>http://thishost/otherpath/pathinfo via external redirection</td>
</tr>
<tr>
<td>^localpath(.*) /otherpath$1 [P]</td>
<td>doesn't make sense, not supported</td>
</tr>
<tr>
<td>^localpath(.*) http://thishost/otherpath$1</td>
<td>/otherpath/pathinfo</td>
</tr>
<tr>
<td>^localpath(.*) http://thishost/otherpath$1 [R]</td>
<td>http://thishost/otherpath/pathinfo via external redirection</td>
</tr>
<tr>
<td>^localpath(.*) http://thishost/otherpath$1 [P]</td>
<td>doesn't make sense, not supported</td>
</tr>
<tr>
<td>^localpath(.*) http://otherhost/otherpath$1</td>
<td>http://otherhost/otherpath/pathinfo via external redirection</td>
</tr>
<tr>
<td>^localpath(.*) http://otherhost/otherpath$1 [R]</td>
<td>http://otherhost/otherpath/pathinfo via external redirection (the [R] flag is redundant)</td>
</tr>
<tr>
<td>^localpath(.*) http://otherhost/otherpath$1 [P]</td>
<td>http://otherhost/otherpath/pathinfo via internal proxy</td>
</tr>
</table>
</usage>
</directivesynopsis>
</modulesynopsis>