Is it possible to turn off Mac OS X extension hiding?

Question

On the Mac, a lot of programs hide the .zzz extension by default. Is there a way to turn this behaviour off so that extensions are never hidden by default?

I know I don't actually need it, I just prefer it to be there.

Answer 1

With Finder active, hit Cmd+, to go to preferences. In the advanced section, you will find the option to show file extensions.

Answer 2

AppleShowAllExtensions controls this behavior. It defaults to 0 (false). Read the value by entering this in a terminal:

defaults read -g AppleShowAllExtensions

Set it to 1 (true) by entering the following in a terminal:

defaults write -g AppleShowAllExtensions -bool TRUE

To also restart the Finder so that the change takes effect immediately (rather than after restarting / logging out & back in):

defaults write -g AppleShowAllExtensions -bool TRUE && killall Finder

To reset to the default value (and restart the Finder):

defaults delete -g AppleShowAllExtensions && killall Finder

Resources:

• https://macos-defaults.com/finder/appleshowallextensions.html
• defaults documentation is available at https://keith.github.io/xcode-man-pages/defaults.1.html and https://ss64.com/osx/defaults.html.
• Some basic instructions on using the macOS Terminal app can be found on support.apple.com.
• Duplicate Q&A on a different Stack Exchange site: https://apple.stackexchange.com/questions/423337/what-is-the-terminal-command-for-show-all-filename-extensions