• https://www.maketecheasier.com/change-screenshot-file-format-mac/
• https://www.tekrevue.com/tip/how-to-customize-screenshot-options-in-mac-os-x/

defaults write com.apple.screencapture type png;killall SystemUIServer
defaults write com.apple.screencapture type jpg;killall SystemUIServer
defaults write com.apple.screencapture type gif;killall SystemUIServer
defaults write com.apple.screencapture type tiff;killall SystemUIServer
defaults write com.apple.screencapture type PDF;killall SystemUIServer

defaults write com.apple.screencapture disable-shadow -bool true
defaults write com.apple.screencapture disable-shadow -bool false