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in relation to this question, I'm using the xrandr command in osx to perform operations on my external monitors. Unfortunately it does not appear to be recognising external montitors at all:

Cobrakai$xrandr  --verbose --screen 1
Invalid screen number 1 (display has 1)

Whereas it works fine for screen 0 (my native screen)

Cobrakai$xrandr  --screen 0
xrandr: Failed to get size of gamma for output default
Screen 0: minimum 640 x 480, current 2304 x 1824, maximum 2304 x 1846
default connected 2304x1824+0+0 0mm x 0mm
   1280x800       60.0      2.0  
   1152x720       60.0  
   1024x768       60.0  
   1024x640       60.0  
   800x600        60.0  
   800x500        60.0  
   640x480        60.0  
   720x480        60.0  
   1280x778        1.0  
   1280x1824       1.0  
   1280x1846       2.0  
   2304x1824       1.0* 
   2304x1846       2.0  

Even when other applications can tell that there are many screens (per screenshot) - how do I get xrandr to recognise the additional screens?

enter image description here

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Turns out that at least part of the problem is that the Xrandr utility is designed only to deal with X11 windows and not native osx screens...

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