What is the correct way to obtain the Drupal installed document root?

Question

Inside of a Drupal module I need to obtain the base path where the Drupal site is installed.

For example, if the drupal site is installed at: www.example.com/mysite/ then I want to get '/var/www/myseite'

If it is installed in: www.example.com/ then I want '/var/www'

What is the proper Drupal way to get this? I want to avoid PHP's server variables, as I read they are unreliable.

(Drupal 6 and Drupal 7)

Answer 1

base_path() does this in both D6 and D7.

Answer 2

Addition to Scott Reynen's answer:

In the page.tpl.php template, it's also available in the $base_path variable.

In many cases, you don't even need to know the base path, because the Drupal API functions add it themselves. For instance, to print a link, you could do this:

<?php print '<a href="' . base_path() . 'foo/bar">Foo Bar</a>'; ?>

But the "Drupal way" to do it is to use the l() function:

<?php print l('Foo Bar', 'foo/bar'); ?>

The l() function will automatically add the base path to the href.

Answer 3

To get the complete document root of the file system I use:

$_SERVER['DOCUMENT_ROOT'] . base_path()

On a Linux server you will get something like:

/var/www/html/www.example.com/mysite/

If you only use "base_path()", you will get only:

/mysite/

Same on Drupal 6 and 7.