I have a subdomain - cleveractions.clevercarbon.io. I wish to mask (not redirect) it so that it loads pages from the main domain thus:
cleveractions.clevercarbon.io => clevercarbon.io/cleveractions/
cleveractions.clevercarbon.io/page => clevercarbon.io/cleveractions/page
Within its .htaccess file I put this (based on the answer here):
Options +FollowSymlinks
RewriteEngine On
RewriteBase /
RewriteCond "%{HTTP_HOST}" "^cleveractions\.clevercarbon\.io" [NC]
RewriteCond "%{HTTP_HOST}" "^$"
RewriteRule "^/?(.*)" "https://clevercarbon.io/cleveractions/$1" [L]
The regex seems to be correct because it redirects just as I'd like - but it does not mask.