Htaccess rewriterule / a to / a / b

Question

I try to prepare rewrite rule from directory /a/ to subfolder /a/b/ , but I receive information that my rewrite rule is circular, so I receive as output URL as localhost/a/b/a/b/a/a/b in order to request localhost/a/. I would like to receive:

localhost/a and rewrite to localhost/a/b

I try:

RewriteEngine On
RewriteCond %{REQUEST_URI} !=/a/b
RewriteRule ^/a(.*)$ /a/b/$1 [L]

Answer 1

Inside /a/.htaccess have this rule:

RewriteEngine on
RewriteBase /a/

RewriteRule ^((?!b/).*)$ b/$1 [NC,L,R=302]

If you want to skip actual files/directories from this redirect then use:

RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^((?!b/).*)$ b/$1 [NC,L,R=302]