Rewrite catalog to domain without changing URL

Question

I need to transfer URL from blog.mydomain.com to mydomain.com/blog but I don't have any experiences with mod rewrite.

The blog is on Wordpress with multisite (a was add a new site).

1. Website mydomain.com is in dir .\mysite\
2. Blog is in dir .\wordpress\
3. I created subdomain blog.mydomain.com and use dir .\wordpress\
4. I put .htaccess file into dir .\mysite\
5. In Wordpress I created a new site for URL mysite.com\blog and used Domain Mapping plugin

I need to use blog from url mydomain.com\blog\wordpress_urls

# Redirect and keeep old url mydomain.com/blog/ => blog.mydomain.com
RewriteEngine On
RewriteCond %{HTTP_HOST} ^mydomain.com/blog
RewriteRule ^(.*) http://blog.mydomain.com/$1 [P]

This code work but it was changing ulr. I don't use HTTPS but in future I will.

Answer 1

A rewrite without redirect requires enabled mod_proxy, as well as mod_rewrite and .htaccess through Apache's httpd.conf.

In your .htaccess under the DOCUMENT_ROOT, i.e. /mysite put:

Options +FollowSymLinks -MultiViews
RewriteEngine On
RewriteBase /

#if not already blog.mydomain.com
RewriteCond %{HTTP_HOST} !^blog\.mydomain\.com$ [NC] 
#rewrite request is for blog/* to blog.mydomain.com
RewriteRule ^blog/?$ http://blog.mydomain.com/$1 [L,P,NC] 

_{Note: You may want to specify your preferred canonical URL to avoid search engine penalties for doubled content (here a custom Wordpress sample).}