Thankfully, in most versions of linux you can use the trusty “Prnt Scrn” key on your keyboard to capture whatever it is your doing.
Ubuntu 11.04 will then ask you what you want to call your image and where you want to save it. Simple.
But if you want to save only a selection of your desktop then Print Screen won’t work. At least, not without a fair amount of cropping afterwards.
The best way to capture screen images in Linux is to use a free package: ImageMagick.
In Ubuntu this can be found in the Software Centre, or you can open a terminal window and type the following:
sudo apt-get install imagemagick
This will install ImageMagick for you.
To use ImageMagick, type the following into a terminal window:
Hit enter and your cursor will change to a cross hairs. Click and drag it over the area of your screen that you want to capture, when you release the mouse button the selected area will be saved to a file named “screenshot.png” and stored in your Home Folder.