Select which display is mirrored

[mdreed]

I'd like to mirror my laptop screen to my larger external monitor (when I'm using the larger monitor for a different computer), but I cannot get mirrordisplays to do so. These two commands have the exact same result (mirroring the external monitor to the Retina laptop screen, resulting in tiny text on the laptop):

mirror -l 0 1
mirror -l 1 0

Is this behavior expected? If it can be fixed, is there a way of changing the default behavior when running the app (from e.g. Sherlock).

I'm running 10.14.6, if that matters.

[fcanas]

mirror doesn't do anything to change display resolutions explicitly. And I believe the system freely changes various aspects of display configuration when screens enter and exit a mirrored set. mirror does specify that the first display is the primary, so the two commands could have different effects.

In my experience, the system remembers things like resolutions within a configuration. (e.g. My laptop screen changes resolution depending on whether it's connected to an external monitor.) So it's possible that you can start the display mirroring set, enter display preferences and change display resolutions to the way you like it, and that the system can remember that. If you do it for the opposite mirrored set, it's possible the system would remember that preference separately. But I've never tried it.

[rajkiran20]

I'd like to mirror my laptop screen to my larger external monitor (when I'm using the larger monitor for a different computer), but I cannot get mirrordisplays to do so. These two commands have the exact same result (mirroring the external monitor to the Retina laptop screen, resulting in tiny text on the laptop):

mirror -l 0 1 mirror -l 1 0

Is this behavior expected? If it can be fixed, is there a way of changing the default behavior when running the app (from e.g. Sherlock).

I'm running 10.14.6, if that matters.

Just wanted to thank you. I was about to post a feature request. But your question already answered it :P
I wanted to have display optimised for monitor's display instead of MacBook's. I tried mirror -l A B as suggested in the documentation which didn't help. But the command you have posted mirror -l 1 0 helped. Thanks.

[Stavrak2]

Curiously, MirrorDisplays does what I want it to do when MacOS doesn't.

I'm like OP - I have a Mac connected to an ultra wide screen. Sometimes I need to use that screen for something else.

If I cmd+F1 on Mac, it mirrors the ultra wide onto the Mac screen (which looks horrible, like a letterbox). This happens regardless of which screen is set to be the main screen. You can specify "Optimise for Retina display" and it will do it properly once (mirroring the internal screen onto the external with vertical bars either side) but it doesn't remember this setting.

But curiously, MirrorDisplay app's default is to do what I want - mirror the internal screen onto the external every time.

Why is this? (Don't change it please but it may help others to know how to configure this if theirs doesn't work as expected)