awk正則匹配列中指定的字符

★ 範例一
◆ 打印指定列中匹配80開頭並以80結束的行
● 關係符號註釋
~ 關係操作符
~ 匹配正則
!~ 不匹配正則

[root@xingfujie ~]# cat a.txt
afjdkj 80
lkdjfkja 8080
dfjj 80
jdsalfj 808080
jasj 80
jg 80
xingfujie 80
80 ajfkj
asf 80
80 xingfujie
[root@xingfujie ~]# awk '{if($2~/^80$/)print}' a.txt
afjdkj 80
dfjj 80
jasj 80
jg 80
xingfujie 80
asf 80

★ 範例二
● 範例 2.1
◆ grep -v ffff過濾ipv6的地址，顯示:80的行，刪除A到Z和_對應的行，判斷已:作爲分隔符，打印第三列等於80的行。
[root@xingfujie ~]# netstat -nat | grep -v ffff | grep ":80" | tr -d "[A-Z][_]"| awk -F : '{if($3==80)print}'
tcp        0      0 10.15.201.29:38393          123.125.106.196:80             
tcp        0      0 10.15.201.29:38383          60.28.236.116:80               
tcp        0      0 10.15.201.29:44949          60.28.236.112:80               
tcp        0      0 10.15.201.29:41445          60.28.236.116:80               
tcp        0      0 10.15.201.29:47630          60.28.236.112:80               
tcp        0      0 10.15.201.29:48624          60.28.236.116:80                
tcp        0      0 10.15.201.29:48129          60.28.236.116:80               
tcp        0      0 10.15.201.29:48837          60.28.236.112:80               
tcp        0      0 10.15.201.29:50506          60.28.236.112:80               
tcp        0      0 10.15.201.29:53923          60.28.236.112:80      
● 範例 2.2
◆ 不加grep ":80"一樣可以查出正確結果
[root@xingfujie ~]# netstat -nat | grep -v ffff | tr -d "[A-Z][_]"| awk -F : '{if($3==80)print}'
tcp        0      0 10.15.201.29:60047          118.67.112.70:80               
tcp        0      0 10.15.201.29:49038          123.125.106.196:80             
tcp        0      0 10.15.201.29:37035          123.125.106.196:80             
tcp        0      0 10.15.201.29:35936          118.67.112.70:80               
tcp        0      0 10.15.201.29:35972          60.28.236.112:80               
tcp        0      0 10.15.201.29:35056          60.28.236.116:80               
tcp        0      0 10.15.201.29:48777          60.28.236.112:80               
tcp        0      0 10.15.201.29:47173          60.28.236.116:80               
tcp        0      0 10.15.201.29:53014          60.28.236.116:80             
tcp        0      0 10.15.201.29:51816          60.28.236.112:80               
tcp        0      0 10.15.201.29:53109          60.28.236.112:80             
tcp        0      0 10.15.201.29:52274          60.28.236.112:80               
tcp        0      0 10.15.201.29:49854          60.28.236.116:80             
tcp        0      0 10.15.201.29:50339          60.28.236.112:80               
tcp        0      0 10.15.201.29:60595          60.28.236.116:80