test.lua

while true do
    local sEvent, param = os.pullEvent("key")
    if sEvent == "key" then
        if param == 87 then
            print("Key W")
        elseif param == 65 then
            print("Key A")
        elseif param == 83 then
            print("Key S")
        elseif param == 65 then
            print("Key D")
        end
    end
end