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Using include_path in PHP

Common convention states that include files for a PHP web application should be kept in a given place. This allows the developer to easily find them.

This becomes a headache though when a site is deep and has many subdirectories. You then start seeing code like:

require_once( '../../../../../../includes/config.php' );

This creates a headache for developers since they have to remember where a page is in respect to the includes directory. If the page is moved to a different subdirectory, the path in the require_once (of, if you prefer, include, require, or require_once) statement needs to be changed.

A simple workaround for this is to add the root directory of the site (or whichever directory is just above the includes directory) to PHP's include path.

Let's assume a directory structure like:

  `- www/
      |- logs/
      `- web/
         |- includes/
         |   `- config.php
         |- test/
         |   |- test/
         |   |   `- test /
         |   |       `- test2.php
         |   `- test.php
         `- index.php

In order to include includes/config.php without modifying the include path, each page would use a different path:

  • index.php:
    require_once( 'includes/config.php' );
  • test/test.php:
    require_once( '../includes/config.php' );
  • test/test/test/test2.php:
    require_once( '../../../includes/config.php' );

Now, if /var/www/sites/ is added to PHP's include path, all three scripts can load config.php with the statement:

require_once( 'includes/config.php' );

This clearly reduces the hassle of maintaining and referencing the single directory for includes.

To add the /var/www/sites/ directory to the include path, it must be appended to the include_path configuration setting. To do this for PHP running under Apache using mod_php, the following line can be added in a .htaccess file or directly to the site's VirtualHost paragraph:

php_value include_path '.:/usr/local/lib/php:/var/www/sites/'

(This assumes that PEAR modules are stored under /usr/local/lib/php.)

If this is the only site on the server, the include_path setting can be edited in php.ini. If using a CGI-based PHP, you may be able to create a local php.ini for this same end. Consult the PHP documentation on runtime configuration for more information.