redirect domain to subdirectory without redirect url

How to redirect domain to sub-directory without redirect to  URL ?
Ans:
If you want to redirect your domain name to sub-directory but the url shows only domain name
For example :

http://indianwebportal.com redirect to http://indianwebportal.com/blog but the URL shows only http://indianwebportal.com
Then add the following rules in your .htaccess file.

<IfModule mod_rewrite.c>
RewriteEngine on
RewriteCond %{HTTP_HOST} ^indianwebportal\.com
RewriteRule ^(.*)$ http://www.indianwebportal.com/$1 [R=301,L]
RewriteRule    ^$   blog/    [L]
RewriteRule    (.*)  blog/$1 [L]
</IfModule>

Note: Replace the “indianwebportal.com” to your original domain name and “blog” to your original directory name.
Done