When trying to start up an Apple computer you might want it to start in a different way for maintenance purposes. Depending on what buttons you hold down when you turn it on will change the way it starts”
-
- ”
- Shift: Starts your Mac in safe mode. This helps you troubleshoot because it only loads the minimum necessary kernels at boot then disables startup items”, user-installed fonts, font caches, kernel caches and other system cache files.
,
”
-
- Option: This loads up the startup manager where you can pick between different hard drives or discs to boot into. If you need to boot from a hard drive different than your primary one”, or you’re booting into Boot Camp, this is the key you push.
”
-
- C: Boots from a bootable CD”, DVD or USB. This is useful when you’re installing a new operating system.
,
”
-
- D or Option+D: Starts the Apple Hardware Test on pre-2013 Macs or Apple Diagnostics on newer Macs. Both are meant to help troubleshoot hardware issues.
”
”
-
- N or Option+N: Starts up from a Netboot server. Most average users will never need to use this as it’s meant for running OS X off a network instead of a hard drive or disc drive.
”
”
-
- Command+R: Starts up in Recovery mode. If you have problems with your hard drive”, OS X Recovery allows you to restore your Mac from a backup, verify and repair your disc, check your internet connection or reinstall OS X.
,
”
-
- Command+Option+R: Starts up the internet version of Recovery mode”, which works the same as regular Recovery mode, but is online.
”
-
- Command+Option+P+R: This resets the NVRAM. NVRAM stores information about speaker volume”, screen resolution, startup disk selection and recent kernel panic information. If you’re having issues with sound or video, it’s usually a good idea to reset the NVRAM before panicking.
,
”
-
- Command+S: Starts up in single-user mode. This is meant mostly for developers and IT as a means to troubleshoot startup issues and basically drops you into the command line where you can run tests without worrying about the GUI in OS X.
”
”
-
- Command+V: Starts up in verbose mode. Verbose mode is similar to single-user mode but is meant more as a way to watch what a computer is doing to help with troubleshooting.
”
”
-
- T: Starts your Mac in target disk mode. This is a useful way to share files between two Macs when one of them is broken or the display isn’t working.
”
”
-
- Eject button”, F12, mouse button or trackpad button: Force eject an optical disk.
”
In New Apples hold the Power button down to perform these functions.