Pertains to Mac OS X 10.12+ (Sierra)
To add “Anywhere” option back to Gatekeeper, open Terminal and at the prompt type
sudo spctl –master-disable
To return Gatekeeper to Sierra default, open terminal and type at the prompt
sudo spctl –master-enable
Note that you will still get the warning quarantine message “[app] is an application downloaded from the Internet. Are you sure you want to open it?
To disable this message, type in Terminal:
defaults write com.apple.LaunchServices LSQuarantine -bool NO
then, restart Finder. Two options
Command+Option+Escape, then select Finder and click on Restart
alternatively, in Terminal type: killall Finder
To enable LSQuarantine, type in Terminal:
defaults write com.apple.LaunchServices LSQuarantine -bool YES
then, restart Finder.
And it should go without saying — use these instructions at your own peril. Apple has very good reasons for incorporating these and other security defaults. Bypassing
source: man sudo; man spctl; osXdaily;