How to hide all file extensions in subdirectories of a given folder?
You can easily do this in Terminal with the SetFile command:

To hide file extensions in a directory and all sub-directories:

cd &lt;path to directory&gt;

find . -name "*.*" -exec SetFile -a -E '{}' \; | echo "hiding extensions"


(can change the second * to a particular extension type if you choose)

To show file extensions in a directory and all sub-directories:

cd &lt;path to directory&gt;

find . -name "*.*" -exec SetFile -a -e '{}' \; | echo "showing extensions"