Com um simples loop while , sleep ing entre:
while true; do osascript -e 'tell application "System Events" to set visible of every application process to false'; sleep 1; done
Se você tiver o Homebrew , instale watch ( brew install watch ) e, em seguida, ligue:
watch -n1 osascript -e 'tell application "System Events" to set visible of every application process to false'
... para executá-lo a cada segundo.