What is the proper way to set different gamma values for 2 different displays?

[Richard Bronosky]

this is a laptop that moves between multiple locations.  I think that
prevents me from putting something in the xorg.conf file.  I'd like to
be able to do this from the command line like I do with xgamma when I
don't have an extra display attached.

I'm using xrandr1.2 and intel video.

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.!# RichardBronosky #!.