[X-Unix] screencapture doesn't capture 2nd monitor

[TjL]

What I am trying to accomplish:

	Take full-screen screenshots at a timed interval (using cron)

It's working, partly.  The screenshots are taken at a timed interval.

Except that it is only capturing ONE of my two monitors (I have a  
Macbook + external)

Looking at the man page (excerpt below) makes it sound like the  
default should be to capture both monitors unless you use the -m flag

NAME
      screencapture -- capture and manipulate clipboard contents

SYNOPSIS
      screencapture [-SWcimswx] file

DESCRIPTION
      The screencapture utility is not very well documented to date.   
A list of
      options follows.

...
      -i      Capture screen interactively, by selection or window.   
The con-
              trol key will cause the screen shot to go to the  
clipboard.  The
              space key will toggle between mouse selection and  
window selec-
              tion modes.  The escape key will cancel the interactive  
screen
              shot.

      -m      Only capture the main monitor, undefined if -i is set.

So there's no way to tell it "Capture both monitors" because it seems  
to be setup to do that by default.

Except that it doesn't work for me.

Anyone have any other ideas?

TjL


ps - I wrote a little shell script here that I am calling via cron

http://tj.tntluoma.com/files/take-full-screenshots.sh

which lets me easily toggle what format the screenshots are in and  
saves them all in a specific place