Shell command to get color under mouse cursor (xorg)

Sure you can. But you need another linux package. If you're on Ubuntu just issue:

sudo apt-get install xdotool grabc

Then run grabc but background it

grabc &

Then perform a mouseclick using xdotool

xdotool click 1

The click will be captured by grabc's cursor and the background process will output the color.

But maybe it won't work from a script. For that purposes you might want to look at this topic on the Ubuntu forums.

Or if you don't mind, you can do it with python as described here.

Not really satisfied with the other solution, I tried my ImageMagick idea. Works fine for me! (Depends on xclip, ImageMagick, xdotool, notify-send)

#!/bin/sh
# Get hex rgb color under mouse cursor, put it into clipboard and create a
# notification.

eval $(xdotool getmouselocation --shell)
IMAGE=`import -window root -depth 8 -crop 1x1+$X+$Y txt:-`
COLOR=`echo $IMAGE | grep -om1 '#\w\+'`
echo -n $COLOR | xclip -i -selection CLIPBOARD
notify-send "Color under mouse cursor: " $COLOR

EDIT:

Now using Gnome Shell, I have problems with the above solution (import won't take a screenshot of the visible windows, I don't know why. Hints are welcome). An alternative is to use a (fast) screenshot taker like scrot and use convert instead of import:

#!/bin/sh
# Get hex rgb color under mouse cursor, put it into clipboard and create a
# notification.

scrot --overwrite /tmp/copycolor.png
eval $(xdotool getmouselocation --shell)
IMAGE=`convert /tmp/copycolor.png -depth 8 -crop 1x1+$X+$Y txt:-`
COLOR=`echo $IMAGE | grep -om1 '#\w\+'`
echo -n $COLOR | xclip -i -selection CLIPBOARD
notify-send "Color under mouse cursor: " $COLOR

Update 2020: Newer versions of scrot require the "--overwrite" option to be set for this to work.

Another method to get the pixel color, based on @Christian's excellent answer:

eval $(xdotool getmouselocation --shell)
xwd -root -silent | convert xwd:- -depth 8 -crop "1x1+$X+$Y" txt:- | grep -om1 '#\w\+'

xwd is significantly faster than import on my system.