How to properly strip part of url (without 301 response code)?

Question

htaccess

there is a structure:
site.ru/dir1/folder1/index.php
site.ru/dir1/folder2/index.php
site.ru/dir1/folder3/index.php
.............. ...............
how to trim the first part of the url?
To url like:

site.ru/dir1/folder1/ или site.ru/dir1/folder1/index.php

became like this:
site.ru/folder1/ или site.ru/folder1/index.php

Answer 1

RewriteEngine On

RewriteCond %{ENV:REDIRECT_STATUS}   ^$
RewriteCond %{DOCUMENT_ROOT}/dir1/$1 -d
RewriteRule ^([^/]+)/.*$ /dir1/$0 [L]

Add to the beginning of .htaccess in the root of the site.