If you don’t wanna clutter your desktop (mac only) with random screenshots here’s what you gotta do:
$ defaults write com.apple.screencapture location ~/Desktop/screenshots
$ killall SystemUIServer
Now every time you press CMD + SHIFT + 3 your mac will save the screenshot inside screenshots/ folder on your desktop.
Cool. With yuuge thanks to @sarah_edo for this tip.
Marvin Danig 