Password protect MacBook while keeping iTunes running

To keep any application active but to lock the machine you can try the following steps.

1. Launch the “Keychain Access” application located in /Applications/Utilities.
2. Choose “Show Status in Menu Bar” from the View menu.
3. Now you have a lock in the menu bar. Use this menu to:
4. Click on the "lock icon" in your menu bar
5. Select "Lock Screen"

This activates Screen Effects which requires your password to unlock screen, but does not stop what is currently active on the OS

Another way to keep any application active but to lock the machine you can try the following steps.

1. Open System Preferences

   a. Select the Preference Pane "Security"

   b. Choose the "General" tab

   c. Check "Require password"

   d. On 10.6 & 10.7 you can also set the time in which you would like to wait prior to initiating the lock (in this case you may want to choose "immediately")

2. Select "Show All" Preference Panes

3. Select the Preference Pane "Desktop & Screen Saver"

   a. Set the "Start screen saver" at its minimum (3 min)

After 3 min of no use your machine will start the screen saver and when the screen saver is stopped you will be prompted to type your Username and Password.

HOWEVER: (Though I like JW8 slick use of Hot Corners you do not need to set them up nor do you need to wait 3 minutes for the Screen Saver to begin, you can simply use the following key-combo

Crtl-Shift-Eject

You could also try the following commands if you have ambitions to create a short script.

NOTE: If a script sounds like something you would like to create you will need to ensure root privileges.

For 10.6 & 10.7 use the following command to make the security immediately follow the Screen Saver's launch:

defaults write com.apple.screensaver askForPasswordDelay 0

For 10.5, 10.6, & 10.7 use the following command to turn on Security Preferences for your Screen Saver:

osascript -e 'tell application "System Events" to set require password to wake of security preferences to true'

To force the screen to lock

open "/System/Library/Frameworks/ScreenSaver.framework/Resources/ScreenSaverEngine.app"

NOTE: You may notice that regardless of how the screen is locked you may be immediately be prompted for your Username & Password as the running app is attempting to stop the Screen Saver/Lock. However, your application (iTunes in this case) will continue to run even while your screen is locked. :–)

You'll need to do two things:

1. Configure your system to require password after sleep or screen saver
2. Set a hot corner for the screensaver (to trigger the screensaver when you want to leave your MacBook) or choose the Login Window from the menu (if you have faster user switching enabled)

Steps to configure require password (see this Apple KB):

1. Choose Apple menu > System Preferences, click Security & Privacy, and then click General.

2. Select Require password... after sleep or screen saver begins. You can adjust the amount of delay before a password is required in the pop-up menu.

To lock your screen quickly with fast user switching enabled, choose Login Window from the menu with your user name. Your applications will remain open and undisturbed, but your computer islocked.

Locking the screen doesn’t prevent other users from turning off the computer and restarting it, and then logging in to their own accounts. If you think this could happen, be sure to save your work before you leave your computer.

You can set the hot corner (if desired) in the Screen Saver preferences section (see this Apple KB):

Use the Screen Saver pane of Desktop & Screen Saver preferences to make images appear on your screen when you aren’t using your computer. You may want to do this to hide the items on your desktop while you’re away.

Hot Corners: Click to set a shortcut for starting or deactivating your screen saver. From Active Screen Corners, choose Start Screen Saver or Disable Screen Saver from the pop-up menu for a corner you want to use, and then click OK.