# Prevent automatically appending file extension when renaming file

file extensionsfinder

I originally have a file called config.yml. When I go into Finder and change its name to config.yml.old, it appears to have changed the extension. However, opening the file in TextWrangler reveals that Mac has just appended a "hidden" .yml at the end, causing the filename to be config.yml.old.yml.

Right now, the only way I can append an extension is by going to Terminal and running mv path/to/config.yml path/to/config.yml.old. Is there actually a way to use the GUI to do this?