GateKeeper is the application on Mac OS 10.8 and above that prevents running applications from unknown sources. On the “Lab” image this can not be enabled since many of the older academic software programs would not be able to run.

Get current status of this setting: sudo spctl --status
Disable GatetKeeper to allow all apps to run: spctl --master-disable
Enable GateKeeper to prevent unknwon apps from running: spctl --master-enable

To see more see:
http://osxdaily.com/2015/05/04/disable-gatekeeper-command-line-mac-osx/