You also know, that Austrians are super-efficient. As such, they have multi-purpose words: You can use the same word in multiple situations.
One of these words is Servus. The word comes from the Latin servant of slave. According to Wikipedia "The phrase is an ellipsis of a Latin expression servus humillimus, domine spectabilis, meaning "[your] most humble servant, [my] noble lord." No subservience is implied in its modern use, which has the force of "at your service." Servus is the origin of the word serf." - But that sounds very complicated.
Servus is great, because you can use it to say Hi when you meet somebody. You can use it when you cheers with somebody. You can use it to say Good Bye.
Or to put it with the words of the late and great Peter Alexander: Every city has their own parting words; in Paris you say "Bonsoir, bonsoir, Paris!" in Roma you say Ciao! Or you sing Arrivederci Roma! But by us in Vienna you simply say Servus!