rename files in web-based folder to match folder name

I need help with changing file names to match the folder name on my website. eg. folder name varanasi: /images/varanasi/VAR03.jpg would become /images/varanasi/varanasi03.jpg. Is there a simple script example someone could provide? Or explain what to look for? I see many similar questions but they don't seem to be for web-based folders.