startup.lua

local password = "thing"
local i = 0
local lock = false
os.pullEvent = os.pullEventRaw
shell.run("clear")
print("password?")
while true do
    if read() == password then
        if lock == false then
            return
            shell.run("clear")
            else
            shell.run("clear")
            print("Locked")
        end
        else
        if lock == false then
            if i == 2 then
                lock = true
            end
            shell.run("clear")
            print("wrong password.")
            print("password?")
            i = i + 1
        else
            shell.run("clear")
            print("Locked")
        end
    end
end