local time_interval = 1.0

function time_interval_func()
    for _, player in ipairs(minetest.get_connected_players()) do
        local name = player:get_player_name()
        minetest.chat_send_player(name, "Hello " .. name)
    end
    minetest.after(time_interval, time_interval_func)
end

minetest.after(time_interval, time_interval_func)