Ajax software     Free javascripts 
↑


Main Page

Testing mod_rewrite

Once mod_rewrite is installed and enabled, you add the rewriting rules to the Apache configuration

file,

httpd.conf

. Apache also lets you save configuration options (including rewriting rules) on a

per-directory basis to a configuration file named

.htaccess

. All you have to do is create a file named

.htaccess

into a directory of your application, and Apache will read it automatically when accessing

that directory.

As with mod_rewrite,

.htaccess

isn’t related to PHP in any way. The

.htaccess

file is strictly an

Apache configuration file. You’ll see how it works in the exercise that follows.

Using

.htaccess

is useful in the following scenarios:

?

You don’t have access to the global configuration file,

httpd.conf

(this tends to be true in a

shared hosting account).

?

You want to have customized configuration options for a particular directory of the application.

?

You want to be able to change the configuration options without restarting Apache. You

are

required to restart Apache after modifying

httpd.conf

, and this is problematic if you have

live applications running on the web server.

All of the exercises in this book are designed to work with the

.htaccess

file. This is the method we

generally recommend for defining rewriting rules, especially in the development stage when the rules

change frequently. This way you avoid restarting Apache every time you change a rewriting rule. It is

also the only solution in a shared hosting environment, where you do not have access to

httpd.conf

and you cannot restart the server, either.

In the upcoming exercise you create a simple rewrite rule that translates

my-super-product.html

to

product.php?product_id=123

. This is the exact scenario that was presented in Figure 3-3.

The

product.php

script is designed to simulate a real product page. The script receives a query string

parameter named

product_id

, and generates a very simple output message based on the value of

this parameter. Figure 3-4 shows the sample output that you’ll get by loading

http://seophp.example

.com/product.php?product_id=123

.

To improve search engine friendliness, you want to be able to access the same page through a static URL:

http://seophp.example.com/my-super-product.html

. In order to implement this feature, you’ll

use — you guessed it! — mod_rewrite.

Older versions of Apache (1.3 and older) may also require you to add the following

line to

httpd.conf

:

AddModule mod_rewrite.c

For this reason, older mod_rewrite tutorials mention this line as obligatory, but it’s

no longer required by new versions of Apache.

49

Chapter 3: Provocative SE-Friendly URLs

c03.qxd:c03 10:39 49

Ajax software     Free javascripts 
→