Redirect Website use .htaccess

today i was confuse again..to write ,edit or redirect website use htaccess...ok...i want to share my experience today

redirect from A.com to www.A.com

RewriteEngine On

RewriteCond %{HTTP_HOST} ^A\.com$ [NC]
RewriteRule ^(.*)$ http://www.A.com/$1 [R=301,L]

redirect from n.A.com to www.A.com

RewriteEngine on

RewriteCond %{HTTP_HOST} ^n.A.com$ [OR]
RewriteCond %{HTTP_HOST} ^www.n.A.com$
RewriteRule ^/?$ "http\:\/\/A\.com" [R=301,L]

From A.com/b to A.com

RewriteEngine on

RewriteCond %{HTTP_HOST} ^A.com$ [OR]
RewriteCond %{HTTP_HOST} ^www.A.com$
RewriteRule ^/?$ "http\:\/\/A\.com\/b" [R=301,L]


From A.com to b.A.com

RewriteEngine on

RewriteCond %{HTTP_HOST} ^A.com$ [OR]
RewriteCond %{HTTP_HOST} ^www.A.com$
RewriteRule ^/?$ "http\:\/\/b\.A\.com" [R=301,L]

from sahid.rumahweb.org To http://www.hellosahid.co.cc/

RewriteEngine on

RewriteCond %{HTTP_HOST} ^sahid.rumahweb.org$ [OR]
RewriteCond %{HTTP_HOST} ^www.sahid.rumahweb.org$
RewriteRule ^/?$ "http\:\/\/www\.hellosahid\.co\.cc" [R=301,L]