Lock Your Screen

Tonight I’m taking a break from working on my lengthy how-to article on data recovery to bring you an easy but extremely effective security tip that you can use in your everyday personal and professional life. You wouldn’t leave your underwear, social security card or bank statement laying out in plain view on your desk at your office while you left to go to lunch, would you? You would most likely put those things in a drawer or, if you’re a particularly cautious cat, you might even put them in a locked drawer. But too often I’ve seen people get up and walk away from their PC, leaving it unsecured. Occasionally I’ve even seen sensitive information on peoples’ screens when they’re not in front of those screens.

There’s a habit I’d like for you to start getting in to when you walk away from your PC. It’s really quick and easy. It works on Windows PCs, Macs and most Linux distros (although the key combination to activate the feature I’m going to tell you about varies from one operating system to the next).

You can lock your screen by depressing a series of keys. When I say “lock your screen,” I mean you can make your PC go to the login screen as though you were not logged in to your PC. Don’t worry! All your programs are still running just fine in the background. The second you enter the correct password and hit the “enter” key, you’ll be right back where you were when you locked the screen. Under ordinary circumstances, there’s no perceivable delay at all.

Try it now. Press the key sequence that corresponds to the operating system you’re using.


Operating System Key Sequence
Windows (Windows Key)+L
Mac OS (newer Macs) CTRL+Shift+Power
Mac OS (older Macs) CTRL+Shift+Eject
Ubuntu CTRL+Alt+L


So a few points of clarification and information:

  • The + character between the buttons in the “Key Sequence” fields means you continue to hold down the previous button as you push the next button. For example, on a newer Mac, we press CTRL+Shift+Power. Thus, we hold down the CTRL button. Then, while continuing to hold down the CTRL button, we also hold down the Shift button. Then, while continuing to hold down both the CTRL and the Shift buttons, we press the Power button. Now, since the sequence is complete, we can release all the buttons.
  • Your “Windows Key” is the key between the left CTRL and Alt buttons that has the Windows logo on it.
  • “Older Macs,” for our purposes, are Macs with optical drives that have an eject button on the keyboard instead of a power button.
  • “New Macs,” for our purposes, are Macs without optical drives that have a power button on the keyboard instead of an eject button.
  • I think most graphical Linux desktop environments support CTRL+Alt+L but I’ve only tested it on Ubuntu.


If you work in a medical environment or if you work with peoples’ personal data, it’s especially important that you start getting in to the habit of locking your screen every time you walk away from your PC. A skilled data thief (or a twelve year old who visited a “hacker website”) could plug in a USB drive and walk off with your sensitive data in less than thirty seconds. And if it’s up on your screen, anyone could see something they shouldn’t or even take a picture of it with their cell phone.

I’m not suggesting you rat your coworkers out or anything, because they’re probably not doing it on purpose, but if you work in a medical environment or with peoples’ personal data, and you see a coworker walk away from their PC without locking it, please lock their PC for them and find a way to gently and tactfully show them how to lock their PC when they walk away from it. Especially if they’ve left sensitive information up on their screen.

Once you’re in the habit of doing this, it takes up very little of your time. To ensure that you form a habit, you should always lock a PC before walking away from it. Even do it on your own PC at home. It should feel wrong to walk away from a PC without locking it. You should have that “did I leave the oven on?” feeling.

A quick, final point that I think might ease the minds of a few readers… locking your screen is not the same thing as logging out of your PC. It is far less time consuming to lock and unlock your screen than it is to log out of your PC and log back in. When you “lock your screen,” all that happens is that your operating system pulls up a “login screen.” Your session can not be continued until you re-authenticate (in most offices this just means typing in your password). Your programs are never exited. Everything you were doing is just hidden behind that login screen. So locking/unlocking your screen is virtually instantaneous. You can get back to work as quickly as you can type your password (unless your office uses two-factor authentication which is very rare as of the date I’m writing this post).

Logging out means you are ending your session on your PC. All the programs you were using are closed out and Windows does all the background stuff it does when someone closes out their user session. Logging out of your PC can take several seconds. Logging back in can take several seconds. And your PC will run a bit slowly at first as your user-specific “startup programs” are initialized.

This article is just about locking your screens. You don’t have to log out. Just please get in to the habit of locking your screens every single time you move away from your PC. It’s a very powerful security tool and it’s something that you can do easily, quickly and mindlessly throughout the course of your day.


Copyright Shaun Whelden 2019
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