日志处理cat、awk、sort、uniq、head多命令使用

需求：根据文件内容，取出现次数最多的前两位ip
基本文件内容查看：

$cat test.txt 
210.242.125.35 adwords.google.com
212.188.10.167 www.google.com
193.192.250.158 images-pos-opensocial.googleusercontent.com
193.192.250.158 clients4.google.com
222.255.120.42 google.com
222.255.120.42 apis.google.com
193.192.250.158 clients2.google.com
193.192.250.158 clients3.google.com
64.233.181.49 mts0.google.com
64.233.181.49 maps.gstatic.com

仅输出ip：

$cat test.txt|awk '{print $1}'
210.242.125.35
212.188.10.167
193.192.250.158
193.192.250.158
222.255.120.42
222.255.120.42
193.192.250.158
193.192.250.158
64.233.181.49
64.233.181.49

按字符串规则排序：

$cat test.txt|awk '{print $1}'|sort
193.192.250.158
193.192.250.158
193.192.250.158
193.192.250.158
210.242.125.35
212.188.10.167
222.255.120.42
222.255.120.42
64.233.181.49
64.233.181.49

去重计数:

$cat test.txt|awk '{print $1}'|sort|uniq -c
      4 193.192.250.158
      1 210.242.125.35
      1 212.188.10.167
      2 222.255.120.42
      2 64.233.181.49

按首列数字倒叙排列输出：
sort -n表示计数从小到大输出 sort -r表示倒序输出

$cat test.txt|awk '{print $1}'|sort|uniq -c|sort -nr
      4 193.192.250.158
      2 64.233.181.49
      2 222.255.120.42
      1 212.188.10.167
      1 210.242.125.35

取对应行数:

$cat test.txt|awk '{print $1}'|sort|uniq -c|sort -nr|head -n 2
      4 193.192.250.158
      2 64.233.181.49

第二种去重计数方式：
采用awk数组的形式计数，然后排序输出内容

$cat test.txt|awk '{a[$1]++}END{for(i in a) print a[i],i}'|sort -nr|head -n 2
4 193.192.250.158
2 64.233.181.49