use -z to test variable so that empty string is same as undefined
use -z to test variable so that empty string is same as undefined

firewalla/firewalla,firewalla/firewalla,MelvinTo/firewalla,firewalla/firewalla,MelvinTo/firewalla,MelvinTo/firewalla,MelvinTo/firewalla,MelvinTo/firewalla,firewalla/firewalla,firewalla/firewalla