How to take a screenshot of the login screen of your Mac

How would you take a high-quality screenshot of the login screen on your Mac?  Is there a way to do this without downloading any special software or using an expensive camera rig?

Yup!  Check it out.

Even in the best lighting taking a screenshot of the login screen with your camera isn’t ideal.  Reflections and dust can really denigrate the quality of the image and it’s really difficult to make the colors commensurate with a traditional screenshot.

High-quality images are critical if you’re creating an eBook or training manual or even just publishing content to the web via a blog.  Blurry photos can ruin your credibility but crisp screenshots can really boost the professionalism of your product.

So what’s the best way to capture the login screen?

Taking a screenshot on your Mac is easy after you’ve already signed into the desktop but doing the same thing before you’ve signed in isn’t so obvious.

Until now.

To pull this trick off you’ll need two Macs connected to the same network because we’re going to use Secure Shell to run an esoteric command built into every version of Mac OS X.

First, sign into the Mac that you wish to capture the login screen then open up System Preferences.

Click on Sharing.

In the left pane make sure Remote Login is enabled then in the right pane under the green Remote Login: On message, make note of the ssh command you need to type from your other Mac.

Mac OS X Enable Remote Login

Alright now we need to bring up the login window so we can capture it.

Click your username in the upper right corner of the screen and then choose the Login Window… option from the drop down box.

Mac OS X Fast User Switching Login Window

If you don’t see this option, you probably need to enable Fast User switching.  In System Preferences, click on Users and Groups and choose Login Options in the left pane.

In the right pane you’ll see a bunch of options but one will say “Show fast user switching menu as…

Put a check there to enable it.

Mac OS X Fast User Switching

Leave this Mac at the login window so we can capture it.

Okay, now back on your other Mac, which is connected to the same network as your first Mac, open up the terminal window and type in:

ssh username@ip address

In the graphic below you can see me connecting to the IP address of my first Mac.

I then changed to the Desktop directory by typing:

cd ~/Desktop

That tilde character is just an alias for my Home directory.  So ~/Desktop is the same thing as /Users/admin/Desktop.

Now we’re  going to employ an arcane Mac command called screencapture.

Welcome to the Mac OS X screencapture command
Type this:

sudo screencapture loginwindow.png

This will create a a screenshot file named loginwindow.png on the desktop of your first Mac.

If you want to change the format you can add the -t parameter followed by the format.  So for example, if you wanted the screenshot to be a jpg you could type:

sudo screencapture -t jpg loginwindow.jpg

I encourage you to read the man page on screencapture because you can do a lot of neat things with it.

For example, you can send a delay of 10 seconds by adding the -T 10 parameter.

If this helped you at all please let me know in the comments!


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Posted in Apple, Mac OS X 10.8 Mountain Lion, Mac OS X 10.9 Mavericks Tagged with: ,