Taking screenshots with the command line, but of specific regions I want to capture a screenshot of a specific region, say 10x, 10y, 200width, 200height using the command line

I am aware of the command "screencapture," so I do


  screencapture -h


and I see this:


  -R &lt; x,y,w,h > capture screen rect


So I try 


  screencapture  -R 0 0 34 20 test1.png


and does not work. It returns a file named 0 that is a capture of the entire screen. I do 


  screencapture Test.png  -R 0 0 34 20


and returns a file named Test.png that is also a capture of the entire screen.

Honorable mention to doing "man screencapture" and see that "-r" does something totally different

Thanks
If you do this:


  screencapture -R0,0,34,20 test1.png


you will get test1.png which has 34 pixels width and 20 pixels height.