Mac OS Grab Screencapture defaults

# Grab File type for screen captures 
defaults write com.apple.screencapture type -string [png,jpg,pdf...]
# Grab Screen capture folder 
defaults write com.apple.screencapture location [~/Desktop/]
# Grab Screenshot file name 
defaults write com.apple.screencapture name -string
# Grab Screenshot file format 
defaults write com.apple.screencapture type -string
# Grab Show shadows on captured windows 
defaults write com.apple.screencapture disable-shadow -boolean-neg

Example:

#!/bin/bash

defaults write com.apple.screencapture type -string PNG
defaults write com.apple.screencapture location ~/Desktop/ScreenShots

# reset the ui server

killall SystemUIServer