Reader Ross Anderson wishes to occasionally sidestep a startup preference setting. He writes:
I’ve configured my Mac running OS X Lion to automatically login to a particular user account. But there are times when I want to instead login to a different account. Is there some way to do that?
To give our readers some context, you can configure your Mac so that it automatically logs into a particular account. To do that, launch System Preferences, select the Security & Privacy preference, click the Lock icon and enter your administrator’s name and password to unlock the preference, and in the General tab make sure the Disable Automatic Login option is unchecked.
If you're currently logged into an account, the easiest way to get to the login screen is to choose Log Out accountname from the Apple menu (where accountname is the name of the account you’re currently logged into). Confirm that you want to do this by clicking on the Log Out button that appears in the resulting window. You’ll be logged out of that account and taken to the login screen where you can choose to log in to a different account.
If you simply want to work in another account without logging out of another, it’s easy. Go to the Users & Groups system preference, unlock that preference in the same way as you did with Security & Privacy, click Login Options at the bottom of the list of users, and in the area to the right be sure that Show Fast User Switching Menu As is enabled. Now when you want to switch accounts, just choose an account name from the menu bar and you’ll be prompted for that account’s password. Enter it and you’ll switch to that account.
Getting to the login screen when starting your Mac is a tougher proposition. If you press and hold the Shift key at startup before you hear the startup chime you’ll eventually be presented with the login screen, but you’ll do so via Safe Boot mode. Not only does it take a couple of extra minutes to start up your Mac (because, as part of the Safe Boot process, the Mac attempts to repair any problems it can find), but after you finally log into the account you want, you’ll find that your login items have been disabled (hence the “Safe” part of “Safe Boot”).
In the old days you could hold Shift after the Apple logo appeared to skirt auto login. I’ve tried that on my MacBook Pro running the latest version of Lion and it doesn’t work.
Because this is a less than ideal way to go about the problem, I’d suggest planning ahead when you can. If you know that you’ll want to boot into a different account after your next shutdown, return to the Security & Privacy system preference and enable that Disable Automatic Login option. When you next boot or restart your Mac, you’ll be taken to the login screen.