``Despite the tons of examples and docs, mod_rewrite is voodoo. Damned cool voodoo, but still voodoo.''

This module operates on the full URLs (including the path-info part) both in per-server context (httpd.conf) and per-directory context - (.htaccess) and can even generate query-string + (.htaccess files and <Directory> + blocks) and can even generate query-string parts on result. The rewritten result can lead to internal sub-processing, external request redirection or even to an internal proxy throughput.

Apache mod_rewrite Flags

Available Languages:

+ +

This document discusses the flags which are available to the +RewriteRule directive, +providing detailed explanations and examples. This is not necessarily +a comprehensive list of all flags available, so be sure to also +consult the reference documentation.

Introduction
The flags

Introduction

RewriteRules can have +their 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.

+RewriteRule pattern target [Flag1,Flag2,Flag3] +

+ +

The flags all have a short form, such as CO, as well as +a longer form, such as cookie. Some flags take one or more +arguments. Flags are not case sensitive.

+ +

The flags

+ +

Each flag has a long and short form. 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.

+ +

Presented here are each of the available flags, along with an example +of how you might use them.

+ +

C|chain

The [C] or [chain] flag indicates that the RewriteRule 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, will be +skipped.

+ + + +

CO|cookie

The [CO], or [cookie] flag, allows you to set a cookie when a +particular RewriteRule +matches. The argument consists of three required fields and two optional +fields.

You must declare a name and value for the cookie to be set, and the +domain for which you wish the cookie to be valid. You may optionally set +the lifetime of the cookie, and the path for which it should be +returned.

By default, the lifetime of the cookie is the current browser +session.

By default, the path for which the cookie will be valid is "/" - that +is, the entire website.

Several examples are offered here:

+ +

+RewriteEngine On +RewriteRule ^/index.html - [CO=frontdoor:yes:.apache.org:1440:/] +

+ +

This rule doesn't rewrite the request (the "-" rewrite target tells +mod_rewrite to pass the request through unchanged) but sets a cookie +called 'frontdoor' to a value of 'yes'. The cookie is valid for any host +in the .apache.org domain. It will be set to expire in 1440 +minutes (24 hours) and will be returned for all URIs.

+ + + +

E|env

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 the +Environment Variables document for more details on how Environment +variables work.

+ +

The following example sets an evironment 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.

+ +

+RewriteRule \.(png|gif|jpg) - [E=image:1] +CustomLog logs/access_log combined env=!image +

+ +

Note that this same effect can be obtained using SetEnvIf. This technique is offered as +an example, not as a recommendation.

+ + +

F|forbidden

Using the [F] flag causes Apache to return a 403 Forbidden status +code to the client. While the same behavior can be accomplished using +the Deny directive, this +allows more flexibility in assigning a Forbidden status.

+ +

The following rule will forbid .exe files from being +downloaded from your server.

+ +

+RewriteRule \.exe - [F] +

+ +

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.

+ + + +

G|gone

The [G] flag forces Apache to return a 410 Gone status with the +response. This indicates that a resource used to be available, but is no +longer available.

+ +

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

+ +

+RewriteRule oldproduct - [G,NC] +

+ + +

H|handler

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:

+ +

+RewriteRule !\. - [H=application/x-httpd-php] +

+ +

+The regular expression above - !\. - will match any request +that does not contain the literal . character. +

+ + +

L|last

The [L] flag causes mod_rewrite to stop processing +the rule set. In most contexts, this means that if the rule matches, no +further rules will be processed.

+ +

If you are using RewriteRule in either +.htaccess files or in +<Directory> 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 .htaccess file or +<Directory> 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.

+ +

It is therefore important, if you are using RewriteRule directives in one of these +context 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.

+ +

The example given here will rewrite any request to +index.php, giving the original request as a query string +argument to index.php, however, if the request is already +for index.php, this rull will be skipped.

+ +

+RewriteCond %{REQUEST_URI} !index\.php +RewriteRule ^(.*) index.php?req=$1 [L] +

+ + +

N|next

+The [N] flag causes the ruleset to start over again from the top. Use +with extreme caution, as it may result in loop. +

+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. +

+ +

+RewriteRule (.*)A(.*) $1B$2 [N] +

+ +

You can think of this as a while loop: While this +pattern still matches, perform this substitution.

+ + + +

NC|nocase

Use of the [NC] flag causes the RewriteRule 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.

+ +

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 +.jpg and .JPG files are both acceptable, for +example.

+ +

+RewriteRule (.*\.(jpg|gif|png))$ http://images.example.com$1 [P,NC] +

+ + +

NE|noescape

By default, special characters, such as & and +?, for example, will be converted to their hexcode +equivalent. Using the [NE] flag prevents that from happening. +

+ +

+RewriteRule ^/anchor/(.+) /bigpage.html#$1 [NE,R] +

+ +

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

+ + + +

NS|nosubreq

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.

+ +

+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|proxy

Use of the [P] flag causes the request to be handled by +mod_proxy, 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:

+ +

+RewriteRule (.*)\.(jpg|gif|png) http://images.example.com$1.$2 [P] +

+ +

Use of the [P] flag implies [L] - that is, the request is immediatly +pushed through the proxy, and any following rules will not be +considered.

+ + + +

PT|passthrough

+ +

+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 trated +as a URI instead. That is to say, the +use of the [PT] flag causes the result of the RewriteRule to be passed back through +URL mapping, so that location-based mappings, such as Alias, for example, might have a chance to take +effect. +

+ +

+If, for example, you have an +Alias +for /icons, and have a RewriteRule pointing there, you should +use the [PT] flag to ensure that the +Alias is evaluated. +

+ +

+Alias /icons /usr/local/apache/icons +RewriteRule /pics/(.+)\.jpg /icons/$1.gif [PT] +

+ +

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

+ + + +

QSA|qsappend

+When the replacement URI contains a query string, the default behavior +of RewriteRule 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. +

+ +

Consider the following rule:

+ +

+RewriteRule /pages/(.+) /page.php?page=$1 [QSA] +

+ +

With the [QSA] flag, a request for /pages/123?one=two will be +mapped to /page.php?page=123&one=two. Without the [QSA] +flag, that same request will be mapped to +/page.php?page=123 - that is, the existing query string +will be discarded. +

+ + +

R|redirect

+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 +http://servername/) then a redirect will be issued to that +location. Otherwise, the current servername will be used to generate the +URL sent with the redirect. +

+ +

+A status code may be specified, in the range 300-399, with a 302 status +code being used by default if none is specified. +

+ +

+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 +http://thishost[:thisport] 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. +

+ + + +

S|skip

The [S] flag is used to skip rules that you don't want to run. This +can be thought of as a goto statement in your rewrite +ruleset. In the following example, we only want to run the RewriteRule if the requested URI +doesn't correspond with an actual file.

+ +

+# 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 +

+ +

This technique is useful because a RewriteCond only applies to the +RewriteRule immediately +following it. Thus, if you want to make a RewriteCond apply +to several RewriteRules, one possible technique is to +negate those conditions and use a [Skip] flag.

+ + + +

T|type

Sets the MIME type with which the resulting response will be +sent. This has the same effect as the AddType directive.

+ +

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

+ +

+# Serve .pl files as plan text +RewriteRule \.pl$ - [T=text/plain] +

+ +

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:

+ +

+# Files with 'IMG' in the name are jpg images. +RewriteRule IMG - [T=image/jpg] +

+ +

Please note that this is a trivial example, and could be better done +using <FilesMatch> +instead. Always consider the alternate +solutions to a problem before resorting to rewrite, which will +invariably be a less efficient solution than the alternatives.

+ + +

The flags + +

+ +

Presented here are each of the available flags, along with an example +of how you might use them.

+ +

C|chain +

The [C] or [chain] flag indicates that the RewriteRule 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, will be +skipped.

+ +

CO|cookie +

The [CO], or [cookie] flag, allows you to set a cookie when a +particular RewriteRule +matches. The argument consists of three required fields and two optional +fields.

By default, the lifetime of the cookie is the current browser +session.

By default, the path for which the cookie will be valid is "/" - that +is, the entire website.

Several examples are offered here:

+ + +RewriteEngine On
+RewriteRule ^/index.html - [CO=frontdoor:yes:.apache.org:1440:/] + + +

+ +

E|env +

+ +

+ + +RewriteRule \.(png|gif|jpg) - [E=image:1]
+CustomLog logs/access_log combined env=!image + + +

Note that this same effect can be obtained using SetEnvIf. This technique is offered as +an example, not as a recommendation.

+ +

F|forbidden +

Using the [F] flag causes Apache to return a 403 Forbidden status +code to the client. While the same behavior can be accomplished using +the Deny directive, this +allows more flexibility in assigning a Forbidden status.

+ +

The following rule will forbid .exe files from being +downloaded from your server.

+ + +RewriteRule \.exe - [F] + + +

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.

+ +

G|gone +

The [G] flag forces Apache to return a 410 Gone status with the +response. This indicates that a resource used to be available, but is no +longer available.

+ +

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

+ + +RewriteRule oldproduct - [G,NC] + +

+ +

H|handler +

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:

+ + +RewriteRule !\. - [H=application/x-httpd-php] + + +

+The regular expression above - !\. - will match any request +that does not contain the literal . character. +

+ +

L|last +

The [L] flag causes mod_rewrite to stop processing +the rule set. In most contexts, this means that if the rule matches, no +further rules will be processed.

+ +

If you are using RewriteRule in either +.htaccess files or in +Directory 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 .htaccess file or +Directory 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.

+ +

It is therefore important, if you are using RewriteRule directives in one of these +context 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.

+ +

+ + +RewriteCond %{REQUEST_URI} !index\.php
+RewriteRule ^(.*) index.php?req=$1 [L] + +

+ +

N|next +

+The [N] flag causes the ruleset to start over again from the top. Use +with extreme caution, as it may result in loop. +

+ + +RewriteRule (.*)A(.*) $1B$2 [N] + + +

You can think of this as a while loop: While this +pattern still matches, perform this substitution.

+ +

NC|nocase +

Use of the [NC] flag causes the RewriteRule 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.

+ +

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 +.jpg and .JPG files are both acceptable, for +example.

+ + +RewriteRule (.*\.(jpg|gif|png))$ http://images.example.com$1 [P,NC] + +

+ +

NE|noescape +

By default, special characters, such as & and +?, for example, will be converted to their hexcode +equivalent. Using the [NE] flag prevents that from happening. +

+ + +RewriteRule ^/anchor/(.+) /bigpage.html#$1 [NE,R] + + +

+ +

NS|nosubreq +

+ +

+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|proxy +

Use of the [P] flag causes the request to be handled by +mod_proxy, 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:

+ + +RewriteRule (.*)\.(jpg|gif|png) http://images.example.com$1.$2 [P] + + +

Use of the [P] flag implies [L] - that is, the request is immediatly +pushed through the proxy, and any following rules will not be +considered.

+ +

PT|passthrough + +

+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 trated +as a URI instead. That is to say, the +use of the [PT] flag causes the result of the RewriteRule to be passed back through +URL mapping, so that location-based mappings, such as Alias, for example, might have a chance to take +effect. +

+ +

+If, for example, you have an +Alias +for /icons, and have a RewriteRule pointing there, you should +use the [PT] flag to ensure that the +Alias is evaluated. +

+ + +Alias /icons /usr/local/apache/icons
+RewriteRule /pics/(.+)\.jpg /icons/$1.gif [PT] + + +

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

+ +

QSA|qsappend +

+When the replacement URI contains a query string, the default behavior +of RewriteRule 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. +

+ +

Consider the following rule:

+ + +RewriteRule /pages/(.+) /page.php?page=$1 [QSA] + + +

+ +

R|redirect +

+ +

+A status code may be specified, in the range 300-399, with a 302 status +code being used by default if none is specified. +

+ +

S|skip +

The [S] flag is used to skip rules that you don't want to run. This +can be thought of as a goto statement in your rewrite +ruleset. In the following example, we only want to run the RewriteRule if the requested URI +doesn't correspond with an actual file.

+ + +# 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 + + +

This technique is useful because a RewriteCond only applies to the +RewriteRule immediately +following it. Thus, if you want to make a RewriteCond apply +to several RewriteRules, one possible technique is to +negate those conditions and use a [Skip] flag.

+ +

T|type +

Sets the MIME type with which the resulting response will be +sent. This has the same effect as the AddType directive.

+ +

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

+ + +# Serve .pl files as plan text +RewriteRule \.pl$ - [T=text/plain] + + +

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:

+ + +# Files with 'IMG' in the name are jpg images.
+RewriteRule IMG - [T=image/jpg] + + +

Please note that this is a trivial example, and could be better done +using FilesMatch +instead. Always consider the alternate +solutions to a problem before resorting to rewrite, which will +invariably be a less efficient solution than the alternatives.

+ +

See also

See also

Documentation

Apache mod_rewrite Flags

See also

Introduction

The flags

C|chain

CO|cookie

E|env

F|forbidden

G|gone

H|handler

L|last

N|next

NC|nocase

NE|noescape

NS|nosubreq

P|proxy

PT|passthrough

QSA|qsappend

R|redirect

S|skip

T|type

URL Rewriting Guide

See also

Canonical URLs

See also

Webcluster through Homogeneous URL Layout

See also

Regular Expressions

RewriteRule basics

Rewrite Flags

Rewrite conditions

Rewrite maps

.htaccess files

Environment Variables

Example

See also

Internal Processing