Você pode executar um AppleScript assim:
osascript -e 'tell application "System Events" to tell process "Notification Center"
click menu bar item 1 of menu bar 2
delay 0.1
repeat while exists button 1 of UI element 1 of row 2 of table 1 of scroll area 1 of window 1
click button 1 of UI element 1 of row 2 of table 1 of scroll area 1 of window 1
end repeat
click menu bar item 1 of menu bar 2
end tell'