Some time ago, I have written about taking screenshots with Linux. But at that time I did not know about scrot, so I am now going to write about scrot. Scrot stands for screen shot
You will have to install it, as it usually is not installed on most Linux distributions, so using your package manager install it.
How to use it
To get an instant screenshot
To have scrot wait until you orginize your screen.
scrot -d 10 file.jpg
That will enter a delay of 10 seconds before taking the screenshot.
If you want scrot to display the countdown.
scrot -d 10 -c file.png
If you want to select a window, or a rectangle with the mouse use -s
scrot -s file.png
If you want the window be captured with the border
scrot -s -b file.png
Two more useful options.
Set the quality of the picture, de default is 75%.
scrot -s -b -q 90 file.png
Finally create a thumbnail, together with the screenshot, you will have to enter the percentage of the size the thumb will have, of the original picture.
scrot -t 20 file.png
You will get two files.
file.png (the original) file-thumb.png (The thumbnail, in this case of 20% the size of the original).