local sSide = "back"

local function printCenter(mon, txt)
  local w, h = mon.getSize()
  local x = math.floor((w / 2) - (#txt / 2))
  local y = math.floor((h / 2))
  mon.setCursorPos(x, y)
  mon.write(txt)
end

local monitor = peripheral.wrap(sSide)

while true do
shell.run("clear")
local nTime = os.time()
printCenter(monitor, textutils.formatTime(nTime, true)))
sleep(1)
end