起步上台

我从netstat命令中提取了如下信息作为用例：

  1. $ cat netstat.txt
  2. Proto Recv-Q Send-Q Local-Address          Foreign-Address             State
  3. tcp        0      0 0.0.0.0:3306           0.0.0.0:*                   LISTEN
  4. tcp        0      0 0.0.0.0:80             0.0.0.0:*                   LISTEN
  5. tcp        0      0 127.0.0.1:9000         0.0.0.0:*                   LISTEN
  6. tcp        0      0 coolshell.cn:80        124.205.5.146:18245         TIME_WAIT
  7. tcp        0      0 coolshell.cn:80        61.140.101.185:37538        FIN_WAIT2
  8. tcp        0      0 coolshell.cn:80        110.194.134.189:1032        ESTABLISHED
  9. tcp        0      0 coolshell.cn:80        123.169.124.111:49809       ESTABLISHED
  10. tcp        0      0 coolshell.cn:80        116.234.127.77:11502        FIN_WAIT2
  11. tcp        0      0 coolshell.cn:80        123.169.124.111:49829       ESTABLISHED
  12. tcp        0      0 coolshell.cn:80        183.60.215.36:36970         TIME_WAIT
  13. tcp        0   4166 coolshell.cn:80        61.148.242.38:30901         ESTABLISHED
  14. tcp        0      1 coolshell.cn:80        124.152.181.209:26825       FIN_WAIT1
  15. tcp        0      0 coolshell.cn:80        110.194.134.189:4796        ESTABLISHED
  16. tcp        0      0 coolshell.cn:80        183.60.212.163:51082        TIME_WAIT
  17. tcp        0      1 coolshell.cn:80        208.115.113.92:50601        LAST_ACK
  18. tcp        0      0 coolshell.cn:80        123.169.124.111:49840       ESTABLISHED
  19. tcp        0      0 coolshell.cn:80        117.136.20.85:50025         FIN_WAIT2
  20. tcp        0      0 :::22                  :::*                        LISTEN

下面是最简单最常用的awk示例，其输出第1列和第4例，

  • 其中单引号中的被大括号括着的就是awk的语句，注意，其只能被单引号包含。
  • 其中的$1..$n表示第几例。注：$0表示整个行。
  1. $ awk '{print $1, $4}' netstat.txt
  2. Proto Local-Address
  3. tcp 0.0.0.0:3306
  4. tcp 0.0.0.0:80
  5. tcp 127.0.0.1:9000
  6. tcp coolshell.cn:80
  7. tcp coolshell.cn:80
  8. tcp coolshell.cn:80
  9. tcp coolshell.cn:80
  10. tcp coolshell.cn:80
  11. tcp coolshell.cn:80
  12. tcp coolshell.cn:80
  13. tcp coolshell.cn:80
  14. tcp coolshell.cn:80
  15. tcp coolshell.cn:80
  16. tcp coolshell.cn:80
  17. tcp coolshell.cn:80
  18. tcp coolshell.cn:80
  19. tcp coolshell.cn:80
  20. tcp :::22

我们再来看看awk的格式化输出，和C语言的printf没什么两样：

  1. $ awk '{printf "%-8s %-8s %-8s %-18s %-22s %-15s\n",$1,$2,$3,$4,$5,$6}' netstat.txt
  2. Proto    Recv-Q   Send-Q   Local-Address      Foreign-Address        State
  3. tcp      0        0        0.0.0.0:3306       0.0.0.0:*              LISTEN
  4. tcp      0        0        0.0.0.0:80         0.0.0.0:*              LISTEN
  5. tcp      0        0        127.0.0.1:9000     0.0.0.0:*              LISTEN
  6. tcp      0        0        coolshell.cn:80    124.205.5.146:18245    TIME_WAIT
  7. tcp      0        0        coolshell.cn:80    61.140.101.185:37538   FIN_WAIT2
  8. tcp      0        0        coolshell.cn:80    110.194.134.189:1032   ESTABLISHED
  9. tcp      0        0        coolshell.cn:80    123.169.124.111:49809  ESTABLISHED
  10. tcp      0        0        coolshell.cn:80    116.234.127.77:11502   FIN_WAIT2
  11. tcp      0        0        coolshell.cn:80    123.169.124.111:49829  ESTABLISHED
  12. tcp      0        0        coolshell.cn:80    183.60.215.36:36970    TIME_WAIT
  13. tcp      0        4166     coolshell.cn:80    61.148.242.38:30901    ESTABLISHED
  14. tcp      0        1        coolshell.cn:80    124.152.181.209:26825  FIN_WAIT1
  15. tcp      0        0        coolshell.cn:80    110.194.134.189:4796   ESTABLISHED
  16. tcp      0        0        coolshell.cn:80    183.60.212.163:51082   TIME_WAIT
  17. tcp      0        1        coolshell.cn:80    208.115.113.92:50601   LAST_ACK
  18. tcp      0        0        coolshell.cn:80    123.169.124.111:49840  ESTABLISHED
  19. tcp      0        0        coolshell.cn:80    117.136.20.85:50025    FIN_WAIT2
  20. tcp      0        0        :::22              :::*                   LISTEN