q.lua

local a = ...
if not a then error("Must include a valid command sequence") end
local cmds = {
    ["l"]=turtle.turnLeft,
    ["r"]=turtle.turnRight,
    ["d"]=turtle.down,
    ["u"]=turtle.up,
    ["f"]=turtle.forward,
    ["b"]=turtle.back,
    ["a"]=function() turtle.turnLeft() turtle.turnLeft() end,
    ["s"]=os.reboot
}
for c,rep in a:gmatch("(%a)(%d*)") do
    local cmd = cmds[c]
    if not cmd then error("Unrecognised command: "..c) end
    if tonumber(rep) then
        for i=1,tonumber(rep) do
            cmd()
        end
    else cmd() end
end