WAMP + directory alias + Drupal clean URLs

I have WAMP installed on my pc where I would like to run Drupal 6.

When I'm installing Drupal, I get the option to activate Clean URLs.

First I put my Drupal install in the www folder and I could choose to enable the clean URLs, but for backup reasons I moved it outside the www folder and created an alias the would point to the folder. When I installed Drupal again, I couldn't choose to enable clean URLs anymore; the option was grayed out.

I would like to know why this happens; it seems some Apache module or PHP extension isn't available outside the www folder.

Just to be sure, I also tried an XAMPP install and created an alias w开发者_高级运维ith the some code lines as in the WAMP server but that worked, for some reason. The Apache version in WAMP isn't the same as the XAMPP install but I don't really think that is relevant.

I believe it's an config error in WAMP but I can't find out what.

Clean URLs doesn't work in the directory you copied Drupal because for that directory the directive AllowOverride is not set to All.
Drupal requires that every directives found in .htaccess files are enabled, in order to enable clean URLs; the directive AllowOverride, when set to All, allows to use all the directives that a .htaccess can contain.

The reason that in one case you can select the the option to enable the clean URLs, and in the other case is not selectable, is that Drupal, during its installation verifies the server is set to work with clean URLs, and change the form field to read-only if the server cannot support such feature.

To notice that the .htaccess file provided from Drupal can possibly need to be edited, in order to enable the clean URLs, as reported in the following comments, found inside the .htaccess file.

# Modify the RewriteBase if you are using Drupal in a subdirectory or in a
# VirtualDocumentRoot and the rewrite rules are not working properly.
# For example if your site is at http://example.com/drupal uncomment and
# modify the following line:
# RewriteBase /drupal
#
# If your site is running in a VirtualDocumentRoot at http://example.com/,
# uncomment the following line:
# RewriteBase /