script087
题目
注：题目来源于 SHELL30 netstat练习2-查看和3306端口建立的连接。
假设 netstat 命令运行的结果我们存储在 nowcoder.txt 里，格式如下：
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:6160 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.53:53 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp 0 0 172.16.56.200:41856 172.16.34.144:3306 ESTABLISHED
tcp 0 0 172.16.56.200:49822 172.16.0.24:3306 ESTABLISHED
tcp 0 0 172.16.56.200:49674 172.16.0.24:3306 ESTABLISHED
tcp 0 0 172.16.56.200:42316 172.16.34.143:3306 ESTABLISHED
tcp 0 0 172.16.56.200:44076 172.16.240.74:6379 ESTABLISHED
tcp 0 0 172.16.56.200:49656 172.16.0.24:3306 ESTABLISHED
tcp 0 0 172.16.56.200:58248 100.100.142.4:80 TIME_WAIT
tcp 0 0 172.16.56.200:50108 172.16.0.24:3306 ESTABLISHED
tcp 0 0 172.16.56.200:41944 172.16.34.144:3306 ESTABLISHED
tcp 0 0 172.16.56.200:35548 100.100.32.118:80 TIME_WAIT
tcp 0 0 172.16.56.200:39024 100.100.45.106:443 TIME_WAIT
tcp 0 0 172.16.56.200:41788 172.16.34.144:3306 ESTABLISHED
tcp 0 0 172.16.56.200:58260 100.100.142.4:80 TIME_WAIT
tcp 0 0 172.16.56.200:41812 172.16.34.144:3306 ESTABLISHED
tcp 0 0 172.16.56.200:41854 172.16.34.144:3306 ESTABLISHED
tcp 0 0 172.16.56.200:58252 100.100.142.4:80 TIME_WAIT
tcp 0 0 172.16.56.200:49586 172.16.0.24:3306 ESTABLISHED
tcp 0 0 172.16.56.200:41754 172.16.34.144:3306 ESTABLISHED
tcp 0 0 172.16.56.200:50466 120.55.222.235:80 TIME_WAIT
tcp 0 0 172.16.56.200:38514 100.100.142.5:80 TIME_WAIT
tcp 0 0 172.16.56.200:49832 172.16.0.24:3306 ESTABLISHED
tcp 0 0 172.16.56.200:52162 100.100.30.25:80 ESTABLISHED
tcp 0 0 172.16.56.200:50372 172.16.0.24:3306 ESTABLISHED
tcp 0 0 172.16.56.200:50306 172.16.0.24:3306 ESTABLISHED
tcp 0 0 172.16.56.200:49600 172.16.0.24:3306 ESTABLISHED
tcp 0 0 172.16.56.200:41908 172.16.34.144:3306 ESTABLISHED
tcp 0 0 172.16.56.200:60292 100.100.142.1:80 TIME_WAIT
tcp 0 0 172.16.56.200:37650 100.100.54.133:80 TIME_WAIT
tcp 0 0 172.16.56.200:41938 172.16.34.144:3306 ESTABLISHED
tcp 0 0 172.16.56.200:49736 172.16.0.24:3306 ESTABLISHED
tcp 0 0 172.16.56.200:41890 172.16.34.144:3306 ESTABLISHED
udp 0 0 127.0.0.1:323 0.0.0.0:*
udp 0 0 0.0.0.0:45881 0.0.0.0:*
udp 0 0 127.0.0.53:53 0.0.0.0:*
udp 0 0 172.16.56.200:68 0.0.0.0:*
udp6 0 0 ::1:323 :::*
raw6 0 0 :::58 :::* 7
现在需要你查看和本机 3306 端口建立连接并且状态是 established 的所有 IP，按照连接数降序排序。你的脚本应该输出：
10 172.16.0.24
9 172.16.34.144
1 172.16.34.143
脚本一
使用 grep 命令查找 3306 端口建立的连接并且连接状态是 ESTABLISHED 的记录行；然后使用 awk 命令提取第五列；再通过 cut 命令提取 IP 地址（即去除端口号）；通过 sort 命令排序；uniq -c 去重并统计出现次数；再通过 sort 命令按降序排列；最后通过 sed 命令去除行首空格。
grep ":3306.*ESTABLISHED" nowcoder.txt | awk '{print $5}' | cut -d ":" -f 1 | sort | uniq -c | sort -nr | sed 's/[ \t]*//'
脚本二
通过 awk 命令编程和关联数组来完成；其中 /:3306.*ESTABLISHED/ 用来查找 3306 端口建立的连接并且连接状态是 ESTABLISHED 的记录行；在 {} 中将 IP 地址和出现次数存入到关联数组中；然后在 END{} 中循环打印关联数组，输出出现次数和 IP 地址；最后通过 sed 命令去除统计行中的 3306 端口号；sort 命令按降序排列。
awk '/:3306.*ESTABLISHED/{map[$5]++} END{for(k in map) print map[k],k}' nowcoder.txt | sed 's/:3306//' | sort -nr