Tun run commands (things starting with "/") you can use run_cmd like this:
run_cmd("ls Movememory.lua") -- note the missing /
However, you can't send chat messages with lua (probably to avoid spamming). There is /say command but even that doesn't work when executed with lua.
get_bet_info(1).num tells you how many people have bet on Uke. (Keep in mind that you can be Uke and your opponent Tori).
To repeatedly check if someone just bet on Uke you can use the draw2d hook (or any other repeating hook):
local betCount = get_bet_info(1).num
add_hook("draw2d", "bet count", function()
local bc = get_bet_info(1).num
if bc > betCount then
echo("Someone bet on Uke!")
betCount = bc
end
end)
add_hook("end_game", "reset", function()
betCount = 0
end)