It is nothing new that when the user presses certain keys when a computer is turning on it causes some functions to come to light. This is very common on PC when someone wants to enter BIOS and make some adjustments on startup, etc. As well as, the power to boot in test mode.
Well, this situation also occurs on Mac computers. have different key combinations to launch functions or applications when the Mac is already working (force exits of apps that have been frozen; jump from one app to another without having to use the mouse; or invoke Siri with two keys are some of the examples), it is also possible use some key combinations when the Mac is turning on or booting up.
The following functions can be executed as long as we press the —or keys— right after hitting the power button of the computer. Are you prepared with pen and paper? Well go ahead:
- By pressing the «Option ⌥» key: this will make us start the Mac from the external drive we want: CD, DVD, USB memory, etc.
- Pressing the «T» key: we will be able to start in "destination disk mode"; We can connect two computers through a Thunderbolt, USB-C or other cable to be able to copy files; that is, the target Mac becomes an entire external hard drive
- By pressing the «Command ⌘ + V» keys or the «Command ⌘ + S» keys: this will allow to invoke the "verbose mode" or the "single user mode" that will place us on a UNIX environment to solve startup problems. These two modes is for advanced users
- Pressing the «Option ⌥ + Command ⌘ + P + R» keys: with this we will be able to reset the NVRAM or PRAM memory; that is, we will get the memory that is responsible for storing some system settings (sound, resolution, etc.) to reset
- By pressing the «Command ⌘ + R» keys: we managed to boot the Mac from the macOS recovery system. This will help you reinstall the operating system or recover a copy of Time Machine
- Pressing the «Shift ⇧» key: by pressing this key we are able to start in «safe mode» so we can make sure that what prevents us from starting normally is resolved