#!/bin/bash

ipv4_regx="((25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]|[0-9]).){3}(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]|[0-9])"

#不含23:00:00 左闭右开区间

grep '23/Apr/2020:2[0-2]:' nowcoder.txt | grep -Eo $ipv4_regx | sort | uniq | wc -l