前面的就不说了，很简单

15

start
break *main+653
commands
    silent
    set $addr = $rbp-0x18

break *main+738
commands
    silent
    set $local_variable = *(unsigned long long*)$addr
    printf "Current value: %llx\n", $local_variable
    continue
end
continue

16

勉强能用

start
catch syscall read
commands
  silent
  set *(unsigned long long*)($rbp-0x10) = *(unsigned long long*)($rbp-0x18)
  end
  continue
end
continue

Q.E.D.

来都来了，点个广告再走吧(=・ω・=)