Hey,

Every time you change the extension of a file, whether it be an image, movie or a system file you Mac will throw up a warning telling you about the change. Although this is useful most of the time, sometimes you may just want to get rid of it and ignore the warning. Thankfully I was given a solution to this problem allowing you to change this setting with Terminal. From my understanding this tip works in Lion and Snow Leopard, it probably works with older version too.

To remove the warning open up Terminal located in Applications > Utilities. Copy and paste the following:

defaults write com.apple.finder FXEnableExtensionChangeWarning -bool false; killall Finder

This will change the setting and restart Finder so the change takes effect. The warning dialog box will not appear

If you want to revert the change type the following:

defaults write com.apple.finder FXEnableExtensionChangeWarning -bool true; killall Finder

Its only a simple change, however one that I find useful. Really useful if you want to change a lot of file extensions and don’t want to constantly accept the change.

If you have any questions about this tip, please leave a comment.