You may be used to simply pressing the Power button on your Mac to turn it on, but in the case that you need to start up your Mac in a different mode, you’ll need to press a specific key combination to do so. macOS features different modes for troubleshooting which you can activate by pressing the specific key combination during the startup boot process. We’ll cover the macOS boot modes and their specific key combinations briefly below.
How to Enter a Specific Startup Mode
As we mentioned earlier, to enter into any specific mode using any of the key combinations below, you need to first turn on your Mac using the Power button and then immediately press the desired key combination.
Recovery mode lets you access Terminal, repair disks using Disk Utility and reinstall macOS using Recovery mode, which is located on a separate partition on your hard drive.
To enter Recovery mode, press Cmd +R on startup.
Select Startup Disk
If you’d like to select your startup disk or boot from a portable USB, simply press Option while turning on your Mac.
Boot from Optical Media (CD/DVD)
If you have an older Mac that features an optical drive, you can choose to boot up from a CD/DVD containing an installation media.
To do so, press the C key on startup.
Eject Optical Media
Similarly, to eject an optical media that might be stuck in your Mac, press the Eject button, F12 or your mouse/trackpad button on startup until the disc is ejected.
Apple Hardware Test / Apple Diagnostics
Depending on your Mac’s version, you can access an Apple Hardware test or Diagnostics test to detect any possible issues with your hardware. To access it, press the D key on startup.
Safe Mode allows you to launch your Mac with the bare essentials required to start the operating system. In safe mode, you can check your startup disks for errors and make repairs accordingly. This mode will prevent all startup/login items from loading, and will also clear up your system caches.
To launch your Mac in safe mode, simply press Shift on startup.
Target Disk Mode
Target Disk Mode allows you to easily copy files from one Mac hard drive to another. Once in Target Disk Mode, simply connect your Mac to another Mac using the proper cable, and transfer your files to the other hard drive.
Target mode only works when using one of the following cables to connect your Macs:
- Thunderbolt 3 (USB-C)
- Thunderbolt 2
To enter Target Disk mode, press the T key on startup.
Single User Mode
Single User mode boots your Mac into a basic text-based environment with a Unix prompt, in which you can type in commands. It’s for more advanced users that can attempt to troubleshoot issues with their Mac not starting. There’s no GUI or drives mounted on startup in the Single User mode.
To enter the Single User mode, press Cmd + S on startup.
Verbose Mode replaces your Mac’s startup screen with a status report of the processes going on during the startup. If your Mac hangs while starting up, you can use Verbose mode to see what’s going wrong during the startup process and what’s causing it to hang.
To launch Verbose mode, press Cmd + V on startup.
If you have client computers on a network image, you can use the NetBoot service to customize macOS and create custom images for specific users. This will allow you to deploy the images network-wide without having to modify every machine individually.
To boot into Netboot, simply press the N key on startup.
Apple Macs feature a SMC chip – System Management Controller chip that controls various hardware tasks such as fan speeds, power management etc.
You can reset the SMC by pressing Shift + Control + Option.
Let us know in the comments if you know if any other startup methods.