List of iMac Power On Shortcuts
The following keyboard combination shortcuts can be applied just as your Mac is booting – which is why they’re referred to as “iMac power-on shortcuts"!
As your iMac starts up, hold the following keys to achieve the corresponding function:
Option: displays the Startup Manager, and any bootable devices
Shift: starts your iMac in Safe Mode
C: starts your iMac from any bootable optical disc that is present
T: turns your iMac into a massive hard disk drive for any attached FireWire device to save data to
N: allows you to boot your Mac from a NetBoot server
X: useful for anyone with Windows or another operating system set up as a dual boot with Mac OS X, this option forces OS X to boot.
Command+V: this starts your computer in “Verbose Mode", which displays a lot of UNIX code and information
Command+S: this will boot your iMac into Single User Mode, a console that allows you to access command line utilities.