Manage Gatekeeper on Mac OS X Sierra

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 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 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;