Updater

function update(var,value)
  if not fs.exists("saveData") then
    local h = fs.open("saveData", "w")
    h.close()
  end
  if type(value) == "number" then
    value = tostring(value)
  elseif type(value) == "table" then
    local v = "{"
    for i = 1, #value-1 do
      v = v .. tostring(value[i]) .. ","
    end
    v = v .. tostring(value[#value]) .. "}"
    value = v
  elseif type(value) == "string" then
    value = "\""..value.."\""
  end
  local str = fs.open("saveData","r").readAll()
  if str:find(var) then
    str = str:gsub(var.."%=.-%;",var.."="..value..";")
  else
    str = str .."\n"..var.."="..value..";"
  end
  local h = fs.open("saveData","w")
  h.write(str)
  h.close()
end

update("a", 1)
update("b", "frog")
update("c", 4)
local test = {1, 2, 3}
update("test", test)