Creating subdomain to redirect any page or directory

I found my best solution.

Added these lines to .htaccess file.

RewriteCond %{HTTP_HOST} ^sub\.mysite\.com$ [NC]
RewriteRule ^(.*) http://www.external-site-or-directory.com/$1 [L,R]

another best solutions https://www.digitalocean.com/community/questions/redirect-subdomain-to-another-website

simple way to do this is a 2-part solution:

in the .htaccess:

RewriteEngine on
RewriteCond %{HTTP_HOST} !^www\.mysite.com
RewriteCond %{HTTP_HOST} ^(.+).ibrahimmumcu.com
RewriteRule ^([^/]*)$ http://www.ibrahimmumcu.com/subdirectory/%1 [P,L,QSA]

in the vhost config, add (below ServerName):

ServerAlias *.ibrahimmumcu.com

You will need to enable .htaccess by changing

AllowOverride None

To

AllowOverride All

This will change allow people to visit

 kisa.ibrahimmumcu.com

and actually get

www.ibrahimmumcu.com/subdirectory/kisa