How to enable Multi site option in WordPress 3.0 +

Installation

The feature “multi-site” of WordPress is already present in the basic installation, simply activate it.
To enable it, add:
define ('WP_ALLOW_MULTISITE',true);
in wp-config.php.

Log into to your site admin.

Under “Tools” menu appears a new element: “Network Settings.”
You have a choice (if your site is installed on the root domain) between sites on the next install subdomains or subfolders. Choose more click “Install”.

Follow the steps that appear: copy lines in the wp-config.php file and in the htaccess.

In the menu “Greetings,…” in the top right of the admin, you have now entered the “network admin” which gives you an overview on all your sites, and in add new ones.

Multi-domain

For similar sites WordPress are neither on a subdomain or in a subfolder, but on a different domain, you can use the plugin WordPress Mu Maping Domain: http://wordpress.org/extend/plugins / wordpress-mu-domain-mapping/installation /
Copy the file in sunrise.php / wp-content / and add to wp-config.php:

define ('SUNRISE','on');

Go further

For the next sites have created a particular theme, you can add this line in the wp-config.php

define( 'WP_DEFAULT_THEME', 'montheme');

To remove the / blog / which is automatically added to the main site url, you can add functions in the file of the theme:

add_filter("pre_update_option_category_base","cc_remove_blog_slug");
add_filter("pre_update_option_tag_base","cc_remove_blog_slug");
add_filter("pre_update_option_permalink_structure","cc_remove_blog_slug");

function cc_remove_blog_slug($tag_cat_permalink){
if (preg_match ("/ ^ \ / blog \ / /", $ tag_cat_permalink))
return $tag_cat_permalink;
$ New_permalink = preg_replace ("/ ^ \ / blog \ / /", "/", $ tag_cat_permalink);
return $new_permalink;
}