htaccess various rewriting needs - file

Question

I have a website let's say http://myweb.com and I want to migrate it into a subfolder of the root directory http://myweb.com/subfolder/
I need the following things, I guess using the htaccess file:
1) Redirect all non-www to www
2) Redirect all files in the root to equivalent files in the subfolder at the same time changing all htm extension to html, that is a file in the root file.htm must be rewritten to a file in the subfolder like subfolder/file.html
3)I want that in the address is still displayed www.myweb.com rather than www.myweb.com/subfolder
is it all possible? And how? Thanks for any answer

Answer 1

Add these rules to the htaccess in your document root:
RewriteEngine On
# 1) Redirect all non-www to www
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteCond %{HTTP_HOST} !^$
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [L,R=301]
# 2) Redirect all files in the root to equivalent files in the subfolder
# at the same time changing all htm extension to html
RewriteCond %{REQUEST_URI} !^/subfolder/
RewriteRule ^(.*)\.htm$ /subfolder/$1.html [L]
RewriteCond %{REQUEST_URI} !^/subfolder/
RewriteRule ^(.*)$ /subfolder/$1 [L]
The last rules don't have the R flag so they won't cause an external redirect (thus changing what's in the browser's URL address bar).