How to screencapture just the active display in a dual monitor setup?

Question

When I use ⇧+⌘+3 to take a screenshot with my laptop connected to a external monitor, it output a couple of images, one for each display.

Is there any way to take the screenshot of just the active monitor instead of both?

BTW, I know that exist ⇧+⌘+4 that let me select a region, but this is not the idea.

I found the command screencapture that can capture only the main monitor with -m option.

screencapture -m ~/Desktop/screencapture.jpg

But, what about second monitor?

Answer 1

Starting from macOS 10.14 you can do the following:

1. Press ⌘⇧5
2. Select the «Capture entire screen» option
3. Click on the required screen to take its screenshot

Answer 2

I think from looking at Apple's official list of screenshot shortcuts, the shortcut that comes closest to what you're trying to do is

⇧ + ⌘ + 4 and then SPACEBAR.

After pressing that combination, you need to click on the window you want a screenshot of. Since there's no other shortcut on the Apple-provided list that can capture the active screen, I believe you'll have to use this unless there's a third-party solution that allows different key combinations.

Answer 3

This solution works for me using Keyboard Maestro.

Steps to do it:

1. Create a new trigger: name it something like Screenshot Active Monitor
2. Add a hot key trigger. I use Print Screen button on my keyboard (which is F13). You can use any shortcut that work for you.

Add following actions to execute on the above keypress: 1. Type a combination of the keystrokes – Shift + Command + 4 2. Type a Space Keystroke 3. Type the Return Keystroke

Check your active monitor screenshot (that has active window you last accessed) in your saved location for screenshots!

Answer 4

Expanding on your own findings, you can use screencapture in additional ways:

• screencapture -SW ~/Desktop/screencapture.jpg

-S         in window capture mode, capture the screen not the window
-W         start interaction in window selection mode

Now you need to click on a “window” that is big enough to capture the whole screen – the Desktop.

When capturing the main screen, move your mouse to the screen edge where your dock is located and click (even clicking on the Dock, visible or not, captures the whole screen).

Capturing a screen without the Dock, you need to find an area where the Desktop is visible.

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You can capture a rectangle that matches your secondary screen. This is more useful if your monitor layout doesn't change.

For example, given two full-HD monitors, main on the left, you could use this to capture a rectangular area of 1920x1080 starting 1920 pixels to the right (where your secondary monitor starts):

• screencapture -R1920,0,1920,1080 ~/Desktop/screencapture.jpg

-R<x,y,w,h> capture screen rect