Mod rewrite - Revision history

Psmay at 20:12, 15 January 2015

2015-01-15T20:12:07Z

161.253.47.104: /* Only show the real file to Coral Cache */

2005-10-18T19:06:06Z

Only show the real file to Coral Cache

161.253.47.104: /* Available variables */

2005-09-30T22:34:46Z

Available variables

161.253.47.104 at 22:34, 30 September 2005

2005-09-30T22:34:07Z

New page

{{lowercase|title=mod_rewrite}}

'''mod_rewrite''' is a particularly useful tool for tricking the user agent. The point is to allow a user to access a URI by using another. The net effect is almost the same as a redirect, except that no redirect happens—the correct content is automatically passed through!

To get started, simply stuff a few lines into your [[.htaccess]]. The first must be

RewriteEngine on

This essentially boots up mod_rewrite. (Additionally, you can set this to <code>off</code> instead of commenting out all mod_rewrite lines in the file.)

Afterward, you add a rule that screws with the request URI:

RewriteRule ^(.*).txt$ $1.html [L]

This particular rule reroutes any requests to a .txt file to the .html file with the same basename. Simple! The first argument is obviously a regexp pattern. In Apache, as in most programs, the pattern syntax isn't as extensive as in Perl (you can't seem to use a trailing ? to indicate non-greed, for example) but it's still functional. You can lead the entire pattern with a ! to negate it.

The trailing <code>[L]</code> flag is optional; it (like a Perl <code>last</code> or a C <code>break</code>) means to skip the remaining rewrite directives. There are many other flags (see the Apache doc). Multiple flags on the same rule are separated by commas. If there are no flags, also omit the brackets.

<code>[NC]</code> makes the pattern case-insensitive (like Perl <code>/i</code>). <code>[R]</code> causes the use of an HTTP redirect to effect the rewrite.

Before the RewriteRule, you may have one or more <code>RewriteCond</code> lines:

<nowiki>
RewriteCond %{HTTP_USER_AGENT} !^CoralWebPrx/.*http://coralcdn\.org</nowiki>

Leading a RewriteRule with one or more RewriteConds has the effect of only running that RewriteRule if all of the RewriteCond lines apply. The first argument is a search string, and the second is the pattern. Adding an <code>[OR]</code> flag ties this and the following RewriteCond by OR instead of AND.

<code>[NC]</code> also works here.

<code>%{HTTP_USER_AGENT}</code> is one of many variables available for interpolation. The doc lists the available variables.

There are plenty more details and interesting uses; see the docs.

=Examples=

==Only show the real file to Coral Cache==

This example reroutes all requests for .txt files to the script ''redherring'' with the basename as the query string (for example, mono.txt leads to redherring?mono), unless it detects the Coral Cache user agent, in which case it gives the real .txt file. This sort of thing might be useful for using the URI on your own server to track the access before handing off the request to CCDN.

<nowiki>
RewriteEngine on
RewriteCond %{HTTP_USER_AGENT} !^CoralWebPrx/.*http://coralcdn\.org
RewriteRule ^(.*).txt$ redherring?$1 [L]</nowiki>

=Available variables=

=See Also=

[http://httpd.apache.org/docs/1.3/mod/mod_rewrite.html Apache docs: mod_rewrite]

← Older revision		Revision as of 20:12, 15 January 2015
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	'''mod_rewrite''' is a particularly useful tool for tricking the user agent. The point is to allow a user to access a URI by using another. The net effect is almost the same as a redirect, except that no redirect happens—the correct content is automatically passed through!		'''mod_rewrite''' is a particularly useful tool for tricking the user agent. The point is to allow a user to access a URI by using another. The net effect is almost the same as a redirect, except that no redirect happens—the correct content is automatically passed through!
		+
		+	==Hiding a script==
		+
		+	See [[mod_rewrite/Hide a script]].
		+
		+	==General==

	To get started, simply stuff a few lines into your [[.htaccess]]. The first must be		To get started, simply stuff a few lines into your [[.htaccess]]. The first must be

@@ Line 41: / Line 41: @@
 RewriteEngine on
 RewriteCond %{HTTP_USER_AGENT} !^CoralWebPrx/.*http://coralcdn\.org
 RewriteRule ^(.*).txt$ redherring?$1 [L]</nowiki>

@@ Line 44: / Line 44: @@
 =Available variables=
 =See Also=
 [http://httpd.apache.org/docs/1.3/mod/mod_rewrite.html Apache docs: mod_rewrite]