Just a quick test

---
--- Created by yannb.
--- DateTime: 22/10/2021 02:36
---

local chat = peripheral.wrap("back")

while true do
    local _, player, message, uuid = os.pullEvent("chat_message")

    -- We exclude messages starting with "Hello to you too" so we don't
    -- reply to ourselves
    if message:find("[Hh]ello") and not message:find("^Hello to you too") then
        chat.say("Hello to you too " .. player)
    end
end