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<title>RewriteRule Flags - Apache HTTP Server Version 2.4</title>
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<a href="http://www.apache.org/">Apache</a> &gt; <a href="http://httpd.apache.org/">HTTP Server</a> &gt; <a href="http://httpd.apache.org/docs/">Documentation</a> &gt; <a href="../">Version 2.4</a> &gt; <a href="./">Rewrite</a></div><div id="page-content"><div id="preamble"><h1>RewriteRule Flags</h1>
<div class="toplang">
<p><span>Available Languages: </span><a href="../en/rewrite/flags.html" title="English">&nbsp;en&nbsp;</a> |
<a href="../fr/rewrite/flags.html" hreflang="fr" rel="alternate" title="Français">&nbsp;fr&nbsp;</a></p>
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<p>This document discusses the flags which are available to the
<code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> directive,
providing detailed explanations and examples.</p>
</div>
<div id="quickview"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#introduction">Introduction</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_b">B (escape backreferences)</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_bnp">BNP|backrefnoplus (don't escape space to +)</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_c">C|chain</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_co">CO|cookie</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_dpi">DPI|discardpath</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_e">E|env</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_end">END</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_f">F|forbidden</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_g">G|gone</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_h">H|handler</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_l">L|last</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_n">N|next</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_nc">NC|nocase</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_ne">NE|noescape</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_ns">NS|nosubreq</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_p">P|proxy</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_pt">PT|passthrough</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_qsa">QSA|qsappend</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_qsd">QSD|qsdiscard</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_qsl">QSL|qslast</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_r">R|redirect</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_s">S|skip</a></li>
<li><img alt="" src="../images/down.gif" /> <a href="#flag_t">T|type</a></li>
</ul><h3>See also</h3><ul class="seealso"><li><a href="../mod/mod_rewrite.html">Module documentation</a></li><li><a href="intro.html">mod_rewrite introduction</a></li><li><a href="remapping.html">Redirection and remapping</a></li><li><a href="access.html">Controlling access</a></li><li><a href="vhosts.html">Virtual hosts</a></li><li><a href="proxy.html">Proxying</a></li><li><a href="rewritemap.html">Using RewriteMap</a></li><li><a href="advanced.html">Advanced techniques</a></li><li><a href="avoid.html">When not to use mod_rewrite</a></li><li><a href="#comments_section">Comments</a></li></ul></div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="introduction" id="introduction">Introduction</a></h2>
<p>A <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> can have
its behavior modified by one or more flags. Flags are included in
square brackets at the end of the rule, and multiple flags are separated
by commas.</p>
<pre class="prettyprint lang-config">RewriteRule pattern target [Flag1,Flag2,Flag3]</pre>


<p>Each flag (with a few exceptions) has a short form, such as
<code>CO</code>, as well as a longer form, such as <code>cookie</code>. 
While it is most common to use
the short form, it is recommended that you familiarize yourself with the
long form, so that you remember what each flag is supposed to do.
Some flags take one or more arguments. Flags are not case sensitive.</p>

<p>Flags that alter metadata associated with the request (T=, H=, E=)
have no affect in per-directory and htaccess context, when a substitution
(other than '-') is performed during the same round of rewrite processing.
</p>

<p>Presented here are each of the available flags, along with an example
of how you might use them.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_b" id="flag_b">B (escape backreferences)</a></h2>
<p>The [B] flag instructs <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> to escape non-alphanumeric
characters before applying the transformation.</p>
<p>In 2.4.26 and later, you can limit the escaping to specific characters
in backreferences by listing them: <code>[B=#?;]</code>. Note: The space
character can be used in the list of characters to escape, but it cannot be
the last character in the list.</p>

<p><code>mod_rewrite</code> has to unescape URLs before mapping them,
so backreferences are 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>

<pre class="prettyprint lang-config">RewriteRule "^search/(.*)$" "/search.php?term=$1"</pre>


<p>Given a search term of 'x &amp; y/z', a browser will encode it as
'x%20%26%20y%2Fz', making the request 'search/x%20%26%20y%2Fz'. Without the B
flag, this rewrite rule will map to 'search.php?term=x &amp; y/z', which
isn't a valid URL, and so would be encoded as
<code>search.php?term=x%20&amp;y%2Fz=</code>, which is not what was intended.</p>

<p>With the B flag set on this same rule, the parameters are re-encoded
before being passed on to the output URL, resulting in a correct mapping to
<code>/search.php?term=x%20%26%20y%2Fz</code>.</p>

<pre class="prettyprint lang-config">RewriteRule "^search/(.*)$" "/search.php?term=$1" [B,PT]</pre>


<p>Note that you may also need to set <code class="directive"><a href="../mod/core.html#allowencodedslashes">AllowEncodedSlashes</a></code> to <code>On</code> to get this
particular example to work, as httpd does not allow encoded slashes in URLs, and
returns a 404 if it sees one.</p>

<p>This escaping is particularly necessary in a proxy situation,
when the backend may break if presented with an unescaped URL.</p>

<p>An alternative to this flag is using a <code class="directive"><a href="../mod/mod_rewrite.html#rewritecond">RewriteCond</a></code> to capture against %{THE_REQUEST} which will capture
strings in the encoded form.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_bnp" id="flag_bnp">BNP|backrefnoplus (don't escape space to +)</a></h2>
<p>The [BNP] flag instructs <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> to escape the space character
in a backreference to %20 rather than '+'. Useful when the backreference
will be used in the path component rather than the query string.</p>

<p>This flag is available in version 2.4.26 and later.</p>

</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_c" id="flag_c">C|chain</a></h2>
<p>The [C] or [chain] flag indicates that the <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> is chained to the next
rule. That is, if the rule matches, then it is processed as usual and
control moves on to the next rule. However, if it does not match, then
the next rule, and any other rules that are chained together, are
skipped.</p>

</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_co" id="flag_co">CO|cookie</a></h2>
<p>The [CO], or [cookie] flag, allows you to set a cookie when a
particular <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code>
matches. The argument consists of three required fields and four optional
fields.</p>

<p>The full syntax for the flag, including all attributes, is as
follows:</p>

<div class="example"><p><code>
[CO=NAME:VALUE:DOMAIN:lifetime:path:secure:httponly]
</code></p></div>

<p>If a literal ':' character is needed in any of the cookie fields, an 
alternate syntax is available.  To opt-in to the alternate syntax, the cookie 
"Name" should be preceded with a ';' character, and field separators should be
specified as ';'.</p>

<div class="example"><p><code>
[CO=;NAME;VALUE:MOREVALUE;DOMAIN;lifetime;path;secure;httponly]
</code></p></div>

<p>You must declare a name, a value, and a domain for the cookie to be set.</p>

<dl>
<dt>Domain</dt>
<dd>The domain for which you want the cookie to be valid. This may be a
hostname, such as <code>www.example.com</code>, or it may be a domain,
such as <code>.example.com</code>. It must be at least two parts
separated by a dot. That is, it may not be merely <code>.com</code> or
<code>.net</code>. Cookies of that kind are forbidden by the cookie
security model.</dd>
</dl>

<p>You may optionally also set the following values:</p>

<dl>
<dt>Lifetime</dt>
<dd>The time for which the cookie will persist, in minutes.</dd>
<dd>A value of 0 indicates that the cookie will persist only for the
current browser session. This is the default value if none is
specified.</dd>

<dt>Path</dt>
<dd>The path, on the current website, for which the cookie is valid,
such as <code>/customers/</code> or <code>/files/download/</code>.</dd>
<dd>By default, this is set to <code>/</code> - that is, the entire
website.</dd>

<dt>Secure</dt>
<dd>If set to <code>secure</code>, <code>true</code>, or <code>1</code>,
the cookie will only be permitted to be translated via secure (https)
connections.</dd>

<dt>httponly</dt>
<dd>If set to <code>HttpOnly</code>, <code>true</code>, or
<code>1</code>, the cookie will have the <code>HttpOnly</code> flag set,
which means that the cookie is inaccessible to JavaScript code on
browsers that support this feature.</dd>
</dl>

<p>Consider this example:</p>

<pre class="prettyprint lang-config">RewriteEngine On
RewriteRule "^/index\.html" "-" [CO=frontdoor:yes:.example.com:1440:/]</pre>


<p>In the example give, the rule doesn't rewrite the request.
The "-" rewrite target tells mod_rewrite to pass the request
through unchanged. Instead, it sets a cookie
called 'frontdoor' to a value of 'yes'. The cookie is valid for any host
in the <code>.example.com</code> domain. It is set to expire in 1440
minutes (24 hours) and is returned for all URIs.</p>

</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_dpi" id="flag_dpi">DPI|discardpath</a></h2>
<p>The DPI flag causes the PATH_INFO portion of the rewritten URI to be
discarded.</p>
<p>This flag is available in version 2.2.12 and later.</p>
<p>In per-directory context, the URI each <code class="directive">RewriteRule</code>
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
<code class="directive">RewriteRule</code> 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>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_e" id="flag_e">E|env</a></h2>
<p>With the [E], or [env] flag, you can set the value of an environment
variable. Note that some environment variables may be set after the rule
is run, thus unsetting what you have set. See <a href="../env.html">the
Environment Variables document</a> for more details on how Environment
variables work.</p>

<p>The full syntax for this flag is:</p>

<pre class="prettyprint lang-config">[E=VAR:VAL]
[E=!VAR]</pre>


<p><code>VAL</code> may contain backreferences (<code>$N</code> or
<code>%N</code>) which are expanded.</p>

<p>Using the short form</p>

<div class="example"><p><code>
[E=VAR]
</code></p></div>

<p>you can set the environment variable named <code>VAR</code> to an
empty value.</p>

<p>The form</p>

<div class="example"><p><code>
[E=!VAR]
</code></p></div>

<p>allows to unset a previously set environment variable named
<code>VAR</code>.</p>

<p>Environment variables can then be used in a variety of
contexts, including CGI programs, other RewriteRule directives, or
CustomLog directives.</p>

<p>The following example sets an environment variable called 'image' to a
value of '1' if the requested URI is an image file. Then, that
environment variable is used to exclude those requests from the access
log.</p>

<pre class="prettyprint lang-config">RewriteRule "\.(png|gif|jpg)$" "-" [E=image:1]
CustomLog "logs/access_log" combined env=!image</pre>


<p>Note that this same effect can be obtained using <code class="directive"><a href="../mod/mod_setenvif.html#setenvif">SetEnvIf</a></code>. This technique is offered as
an example, not as a recommendation.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_end" id="flag_end">END</a></h2>
<p>Using the [END] flag terminates not only the current round of rewrite
processing (like [L]) but also prevents any subsequent rewrite
processing from occurring in per-directory (htaccess) context.</p>

<p>This does not apply to new requests resulting from external
redirects.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_f" id="flag_f">F|forbidden</a></h2>
<p>Using the [F] flag causes the server to return a 403 Forbidden status
code to the client. While the same behavior can be accomplished using
the <code class="directive"><a href="../mod/mod_access_compat.html#deny">Deny</a></code> directive, this
allows more flexibility in assigning a Forbidden status.</p>

<p>The following rule will forbid <code>.exe</code> files from being
downloaded from your server.</p>

<pre class="prettyprint lang-config">RewriteRule "\.exe" "-" [F]</pre>


<p>This example uses the "-" syntax for the rewrite target, which means
that the requested URI is not modified. There's no reason to rewrite to
another URI, if you're going to forbid the request.</p>

<p>When using [F], an [L] is implied - that is, the response is returned
immediately, and no further rules are evaluated.</p>

</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_g" id="flag_g">G|gone</a></h2>
<p>The [G] flag forces the server to return a 410 Gone status with the
response. This indicates that a resource used to be available, but is no
longer available.</p>

<p>As with the [F] flag, you will typically use the "-" syntax for the
rewrite target when using the [G] flag:</p>

<pre class="prettyprint lang-config">RewriteRule "oldproduct" "-" [G,NC]</pre>


<p>When using [G], an [L] is implied - that is, the response is returned
immediately, and no further rules are evaluated.</p>

</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_h" id="flag_h">H|handler</a></h2>
<p>Forces the resulting request to be handled with the specified
handler. For example, one might use this to force all files without a
file extension to be parsed by the php handler:</p>

<pre class="prettyprint lang-config">RewriteRule "!\." "-" [H=application/x-httpd-php]</pre>


<p>
The regular expression above - <code>!\.</code> - will match any request
that does not contain the literal <code>.</code> character.
</p>

<p>This can be also used to force the handler based on some conditions.
For example, the following snippet used in per-server context allows
<code>.php</code> files to be <em>displayed</em> by <code>mod_php</code>
if they are requested with the <code>.phps</code> extension:</p>

<pre class="prettyprint lang-config">RewriteRule "^(/source/.+\.php)s$" "$1" [H=application/x-httpd-php-source]</pre>


<p>The regular expression above - <code>^(/source/.+\.php)s$</code> - will
match any request that starts with <code>/source/</code> followed by 1 or
n characters followed by <code>.phps</code> literally. The backreference
$1 referrers to the captured match within parenthesis of the regular
expression.</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_l" id="flag_l">L|last</a></h2>
<p>The [L] flag causes <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> to stop processing
the rule set. In most contexts, this means that if the rule matches, no
further rules will be processed. This corresponds to the
<code>last</code> command in Perl, or the <code>break</code> command in
C. Use this flag to indicate that the current rule should be applied
immediately without considering further rules.</p>

<p>If you are using <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> in either
<code>.htaccess</code> files or in
<code class="directive"><a href="../mod/core.html#directory">&lt;Directory&gt;</a></code> sections,
it is important to have some understanding of how the rules are
processed.  The simplified form of this is that once the rules have been
processed, the rewritten request is handed back to the URL parsing
engine to do what it may with it. It is possible that as the rewritten
request is handled, the <code>.htaccess</code> file or
<code class="directive"><a href="../mod/core.html#directory">&lt;Directory&gt;</a></code> section
may be encountered again, and thus the ruleset may be run again from the
start. Most commonly this will happen if one of the rules causes a
redirect - either internal or external - causing the request process to
start over.</p>

<p>It is therefore important, if you are using <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> directives in one of these
contexts, that you take explicit steps to avoid rules looping, and not
count solely on the [L] flag to terminate execution of a series of
rules, as shown below.</p>

<p> An alternative flag, [END], can be used to terminate not only the
current round of rewrite processing but prevent any subsequent
rewrite processing from occurring in per-directory (htaccess)
context. This does not apply to new requests resulting from external
redirects.</p>

<p>The example given here will rewrite any request to
<code>index.php</code>, giving the original request as a query string
argument to <code>index.php</code>, however, the <code class="directive"><a href="../mod/mod_rewrite.html#rewritecond">RewriteCond</a></code> ensures that if the request
is already for <code>index.php</code>, the <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> will be skipped.</p>

<pre class="prettyprint lang-config">RewriteBase "/"
RewriteCond "%{REQUEST_URI}" "!=/index.php"
RewriteRule "^(.*)" "/index.php?req=$1" [L,PT]</pre>

</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_n" id="flag_n">N|next</a></h2>
<p>
The [N] flag causes the ruleset to start over again from the top, using
the result of the ruleset so far as a starting point. Use
with extreme caution, as it may result in loop.
</p>
<p>
The [Next] flag could be used, for example, if you wished to replace a
certain string or letter repeatedly in a request. The example shown here
will replace A with B everywhere in a request, and will continue doing
so until there are no more As to be replaced.
</p>
<pre class="prettyprint lang-config">RewriteRule "(.*)A(.*)" "$1B$2" [N]</pre>

<p>You can think of this as a <code>while</code> loop: While this
pattern still matches (i.e., while the URI still contains an
<code>A</code>), perform this substitution (i.e., replace the
<code>A</code> with a <code>B</code>).</p>

<p>In 2.4.8 and later, this module returns an error after 32,000 iterations to
protect against unintended looping.  An alternative maximum number of 
iterations can be specified by adding to the N flag.  </p>
<pre class="prettyprint lang-config"># Be willing to replace 1 character in each pass of the loop
RewriteRule "(.+)[&gt;&lt;;]$" "$1" [N=64000]
# ... or, give up if after 10 loops
RewriteRule "(.+)[&gt;&lt;;]$" "$1" [N=10]</pre>


</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_nc" id="flag_nc">NC|nocase</a></h2>
<p>Use of the [NC] flag causes the <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> to be matched in a
case-insensitive manner. That is, it doesn't care whether letters appear
as upper-case or lower-case in the matched URI.</p>

<p>In the example below, any request for an image file will be proxied
to your dedicated image server. The match is case-insensitive, so that
<code>.jpg</code> and <code>.JPG</code> files are both acceptable, for
example.</p>

<pre class="prettyprint lang-config">RewriteRule "(.*\.(jpg|gif|png))$" "http://images.example.com$1" [P,NC]</pre>

</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_ne" id="flag_ne">NE|noescape</a></h2>
<p>By default, special characters, such as <code>&amp;</code> and
<code>?</code>, for example, will be converted to their hexcode
equivalent. Using the [NE] flag prevents that from happening.
</p>

<pre class="prettyprint lang-config">RewriteRule "^/anchor/(.+)" "/bigpage.html#$1" [NE,R]</pre>


<p>
The above example will redirect <code>/anchor/xyz</code> to
<code>/bigpage.html#xyz</code>. Omitting the [NE] will result in the #
being converted to its hexcode equivalent, <code>%23</code>, which will
then result in a 404 Not Found error condition.
</p>

</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_ns" id="flag_ns">NS|nosubreq</a></h2>
<p>Use of the [NS] flag prevents the rule from being used on
subrequests. For example, a page which is included using an SSI (Server
Side Include) is a subrequest, and you may want to avoid rewrites
happening on those subrequests. Also, when <code class="module"><a href="../mod/mod_dir.html">mod_dir</a></code>
tries to find out information about possible directory default files
(such as <code>index.html</code> files), this is an internal
subrequest, and you often want to avoid rewrites on such subrequests.
On subrequests, it is not always useful, and can even cause errors, if
the complete set of rules are applied. Use this flag to exclude
problematic 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>

<p>
Images, javascript files, or css files, loaded as part of an HTML page,
are not subrequests - the browser requests them as separate HTTP
requests.
</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_p" id="flag_p">P|proxy</a></h2>
<p>Use of the [P] flag causes the request to be handled by
<code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>, and handled via a proxy request. For
example, if you wanted all image requests to be handled by a back-end
image server, you might do something like the following:</p>

<pre class="prettyprint lang-config">RewriteRule "/(.*)\.(jpg|gif|png)$" "http://images.example.com/$1.$2" [P]</pre>


<p>Use of the [P] flag implies [L] - that is, the request is immediately
pushed through the proxy, and any following rules will not be
considered.</p>

<p>
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 <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>. If not, you will get an
error from the proxy module. Use this flag to achieve a
more powerful implementation of the <code class="directive"><a href="../mod/mod_proxy.html#proxypass">ProxyPass</a></code> directive,
to map remote content into the namespace of the local server.</p>

<div class="warning">
<h3>Security Warning</h3>
<p>Take care when constructing the target URL of the rule, considering
the security impact from allowing the client influence over the set of
URLs to which your server will act as a proxy.  Ensure that the scheme
and hostname part of the URL is either fixed, or does not allow the
client undue influence.</p>
</div>

<div class="warning">
<h3>Performance warning</h3>
<p>Using this flag triggers the use of <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code>, without handling of persistent connections. This
means the performance of your proxy will be better if you set it up with <code class="directive"><a href="../mod/mod_proxy.html#proxypass">ProxyPass</a></code> or
<code class="directive"><a href="../mod/mod_proxy.html#proxypassmatch">ProxyPassMatch</a></code></p>
<p>This is because this flag triggers the use of the default worker, which does not handle connection pooling/reuse.</p>
<p>Avoid using this flag and prefer those directives, whenever you can.</p>
</div>

<p>Note: <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> must be enabled in order
to use this flag.</p>

</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_pt" id="flag_pt">PT|passthrough</a></h2>

<p>
The target (or substitution string) in a RewriteRule is assumed to be a
file path, by default. The use of the [PT] flag causes it to be treated
as a URI instead. That is to say, the
use of the [PT] flag causes the result of the <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> to be passed back through
URL mapping, so that location-based mappings, such as <code class="directive"><a href="../mod/mod_alias.html#alias">Alias</a></code>, <code class="directive"><a href="../mod/mod_alias.html#redirect">Redirect</a></code>, or <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>, for example, might have a
chance to take effect.
</p>

<p>
If, for example, you have an
<code class="directive"><a href="../mod/mod_alias.html#alias">Alias</a></code>
for /icons, and have a <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> pointing there, you should
use the [PT] flag to ensure that the
<code class="directive"><a href="../mod/mod_alias.html#alias">Alias</a></code> is evaluated.
</p>

<pre class="prettyprint lang-config">Alias "/icons" "/usr/local/apache/icons"
RewriteRule "/pics/(.+)\.jpg$" "/icons/$1.gif" [PT]</pre>


<p>
Omission of the [PT] flag in this case will cause the Alias to be
ignored, resulting in a 'File not found' error being returned.
</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>

<p>Note that the <code>PT</code> flag is implied in per-directory
contexts such as
<code class="directive"><a href="../mod/core.html#directory">&lt;Directory&gt;</a></code> sections
or in <code>.htaccess</code> files. The only way to circumvent that
is to rewrite to <code>-</code>.</p>

</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_qsa" id="flag_qsa">QSA|qsappend</a></h2>
<p>
When the replacement URI contains a query string, the default behavior
of <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> is to discard
the existing query string, and replace it with the newly generated one.
Using the [QSA] flag causes the query strings to be combined.
</p>

<p>Consider the following rule:</p>

<pre class="prettyprint lang-config">RewriteRule "/pages/(.+)" "/page.php?page=$1" [QSA]</pre>


<p>With the [QSA] flag, a request for <code>/pages/123?one=two</code> will be
mapped to <code>/page.php?page=123&amp;one=two</code>. Without the [QSA]
flag, that same request will be mapped to
<code>/page.php?page=123</code> - that is, the existing query string
will be discarded.
</p>
</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_qsd" id="flag_qsd">QSD|qsdiscard</a></h2>
<p>
When the requested URI contains a query string, and the target URI does
not, the default behavior of <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> is to copy that query
string to the target URI. Using the [QSD] flag causes the query string
to be discarded.
</p>

<p>This flag is available in version 2.4.0 and later.</p>

<p>
Using [QSD] and [QSA] together will result in [QSD] taking precedence.
</p>

<p>
If the target URI has a query string, the default behavior will be
observed - that is, the original query string will be discarded and
replaced with the query string in the <code>RewriteRule</code> target
URI.
</p>

</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_qsl" id="flag_qsl">QSL|qslast</a></h2>
<p>
By default, the first (left-most) question mark in the substitution
delimits the path from the query string.  Using the [QSL] flag instructs
<code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> to instead split
the two components using the last (right-most) question mark.  </p>

<p>
This is useful when mapping to files that have literal question marks in 
their filename.  If no query string is used in the substitution, 
a question mark can be appended to it in combination with this flag.  </p>

<p> This flag is available in version 2.4.19 and later.</p>

</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_r" id="flag_r">R|redirect</a></h2>
<p>
Use of the [R] flag causes a HTTP redirect to be issued to the browser.
If a fully-qualified URL is specified (that is, including
<code>http://servername/</code>) then a redirect will be issued to that
location. Otherwise, the current protocol, servername, and port number
will be used to generate the URL sent with the redirect.
</p>

<p>
<em>Any</em> valid HTTP response  status code may be specified,
using the syntax [R=305], with a 302 status code being used by
default if none is specified. The status code specified need not
necessarily be a redirect (3xx) status code. However,
if a status code is outside the redirect range (300-399) then the
substitution string is dropped entirely, and rewriting is stopped as if
the <code>L</code> were used.</p>

<p>In addition to response status codes, you may also specify redirect
status using their symbolic names: <code>temp</code> (default),
<code>permanent</code>, or <code>seeother</code>.</p>

<p>
You will almost always want to use [R] in conjunction with [L] (that is,
use [R,L]) because on its own, the [R] flag prepends
<code>http://thishost[:thisport]</code> to the URI, but then passes this
on to the next rule in the ruleset, which can often result in 'Invalid
URI in request' warnings.
</p>

</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_s" id="flag_s">S|skip</a></h2>
<p>The [S] flag is used to skip rules that you don't want to run. The
syntax of the skip flag is [S=<em>N</em>], where <em>N</em> signifies
the number of rules to skip (provided the <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">
RewriteRule</a></code> matches). This can be thought of as a <code>goto</code>
statement in your rewrite ruleset. In the following example, we only want
to run the <code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> if the
requested URI doesn't correspond with an actual file.</p>

<pre class="prettyprint lang-config"># Is the request for a non-existent file?
RewriteCond "%{REQUEST_FILENAME}" "!-f"
RewriteCond "%{REQUEST_FILENAME}" "!-d"
# If so, skip these two RewriteRules
RewriteRule ".?" "-" [S=2]

RewriteRule "(.*\.gif)" "images.php?$1"
RewriteRule "(.*\.html)" "docs.php?$1"</pre>


<p>This technique is useful because a <code class="directive"><a href="../mod/mod_rewrite.html#rewritecond">RewriteCond</a></code> only applies to the
<code class="directive"><a href="../mod/mod_rewrite.html#rewriterule">RewriteRule</a></code> immediately
following it. Thus, if you want to make a <code>RewriteCond</code> apply
to several <code>RewriteRule</code>s, one possible technique is to
negate those conditions and add a <code>RewriteRule</code> with a [Skip] flag. You can
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:</p>
<pre class="prettyprint lang-config"># Does the file exist?
RewriteCond "%{REQUEST_FILENAME}" "!-f"
RewriteCond "%{REQUEST_FILENAME}" "!-d"
# Create an if-then-else construct by skipping 3 lines if we meant to go to the "else" stanza.
RewriteRule ".?" "-" [S=3]

# IF the file exists, then:
    RewriteRule "(.*\.gif)" "images.php?$1"
    RewriteRule "(.*\.html)" "docs.php?$1"
    # Skip past the "else" stanza.
    RewriteRule ".?" "-" [S=1]
# ELSE...
    RewriteRule "(.*)" "404.php?file=$1"
# END</pre>


<p>It is probably easier to accomplish this kind of configuration using
the <code class="directive">&lt;If&gt;</code>, <code class="directive">&lt;ElseIf&gt;</code>, and <code class="directive">&lt;Else&gt;</code> directives instead.</p>

</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="section">
<h2><a name="flag_t" id="flag_t">T|type</a></h2>
<p>Sets the MIME type with which the resulting response will be
sent. This has the same effect as the <code class="directive"><a href="../mod/mod_mime.html#addtype">AddType</a></code> directive.</p>

<p>For example, you might use the following technique to serve Perl
source code as plain text, if requested in a particular way:</p>

<pre class="prettyprint lang-config"># Serve .pl files as plain text
RewriteRule "\.pl$" "-" [T=text/plain]</pre>


<p>Or, perhaps, if you have a camera that produces jpeg images without
file extensions, you could force those images to be served with the
correct MIME type by virtue of their file names:</p>

<pre class="prettyprint lang-config"># Files with 'IMG' in the name are jpg images.
RewriteRule "IMG" "-" [T=image/jpg]</pre>


<p>Please note that this is a trivial example, and could be better done
using <code class="directive"><a href="../mod/core.html#filesmatch">&lt;FilesMatch&gt;</a></code>
instead. Always consider the alternate
solutions to a problem before resorting to rewrite, which will
invariably be a less efficient solution than the alternatives.</p>

<p>
If used in per-directory context, use only <code>-</code> (dash)
as the substitution <em>for the entire round of mod_rewrite processing</em>,
otherwise the MIME-type set with this flag is lost due to an internal
re-processing (including subsequent rounds of mod_rewrite processing).
The <code>L</code> flag can be useful in this context to end the
<em>current</em> round of mod_rewrite processing.</p>

</div></div>
<div class="bottomlang">
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<a href="../fr/rewrite/flags.html" hreflang="fr" rel="alternate" title="Français">&nbsp;fr&nbsp;</a></p>
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