how to enable multi site option in wordpress 3
One of the most important feature in wordpress 3 is that the wordpress blog engine and the wordpress mu (WPMU) is merged and provides the ability to run multiple blogs/site from one wordpress installation.
Though, WPMU is merged, it is not enabled by default. To enable the multi blog/site option you will have to follow set of instructions as explained in this article.
Add the following lines of code in wp-config.php
/** Enable Multisite option */
define('WP_ALLOW_MULTISITE', true);

After enabling multisite option you should see a new menu item “Network ” under “Tools”.

Go to Tools > Network
Now you have two option to select from
- Sub-domain : site1.w3demo.com
- Sub-directories : w3demo.com/site1
To create a sub-domain you have to create a DNS (A Name record) which points to the main site. Once you have a sub-domain, choose sub domain option, provide name of the network ex:w3demo and then fill out admin email and install.

Create a “blogs.dir” directory in /wp-content/. This directory is used to stored uploaded media for your additional sites and must be writeable by the web server.
Add the following to your wp-config.php file above the line reading /* That’s all, stop editing! Happy blogging. */:
define( 'MULTISITE', true );
define( 'SUBDOMAIN_INSTALL', true );
$base = '/';
define( 'DOMAIN_CURRENT_SITE', 'w3demo.com' );
define( 'PATH_CURRENT_SITE', '/' );
define( 'SITE_ID_CURRENT_SITE', 1 );
define( 'BLOG_ID_CURRENT_SITE', 1 );
Edit .htaccess file and add the below lines
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
# uploaded files
RewriteRule ^([_0-9a-zA-Z-]+/)?files/(.+) wp-includes/ms-files.php?file=$2 [L]
# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]
When you done with the above steps re-login to admin section. Now you will see “super admin” menu through which you can create/manage multiple sites. Now you can add any no. of sites/blogs with just few clicks.













