When attempting to change a file extension in OS X Finder a warning dialog will appear. This could be annoying if you know what you’re exactly doing. Turn off the extension change dialog with the following command.
defaults write com.apple.finder FXEnableExtensionChangeWarning -bool false
To make the command take effect, you need to restart the Finder.
killall Finder
To reverse the change:
defaults write com.apple.finder FXEnableExtensionChangeWarning -bool true
Restart finder
