please refer to:
http://tips.webdesign10.com/how-to-take-a-screenshot-on-ubuntu-linux
import MyScreenshot.png
or
sleep 10; import -window root MyScreenshot2.png
http://tips.webdesign10.com/how-to-take-a-screenshot-on-ubuntu-linux
import MyScreenshot.png
or
sleep 10; import -window root MyScreenshot2.png