Question

how do I redirect http://mysite.com/folder/category-old/ to http://mysite.com/folder/category-new/?

NOTE:
1. the same ‘category’ exists in all folders.
2. “folder” is variable and could be “folder2” or “folder3”
3. the final folder will always be /category-new/

Answer 1

Use mod_rewrite. Place something like this in .htaccess in the root directory:

Options +FollowSymLinks
RewriteEngine on
RewriteRule ^(.*)/category-old/(.*)$ $1/category-new/$2 [R,L] 

See http://httpd.apache.org/docs/2.2/mod/mod_rewrite.html for more info.