DAY 19

阅读量：6926 次

发布时间：2019-06-27

本文共 6800 字，大约阅读时间需要 22 分钟。

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第19天周4 20180802 授课老师-李泳谊

作者: 邢永胜

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awk扩展

awk '条件{动作}'

条件 NR==3 或 NR>=3 找出什么样的行

动作命令 print

ifconfig eth0 | awk 'NR==2{print $2}'  ifconfig eth0 | awk -F '[: ]+' 'NR==2{print $4}'

题目1 取出网卡ip

[root@as4k ~]# ifconfig eth0  eth0      Link encap:Ethernet  HWaddr 00:0C:29:02:4B:F5            inet addr:192.168.56.11  Bcast:192.168.56.255  Mask:255.255.255.0          inet6 addr: fe80::20c:29ff:fe02:4bf5/64 Scope:Link          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1          RX packets:311780 errors:0 dropped:0 overruns:0 frame:0          TX packets:248323 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:1000           RX bytes:82606035 (78.7 MiB)  TX bytes:142937754 (136.3 MiB)  [root@as4k ~]# ip a s eth0  2: eth0: 
    
      mtu 1500 qdisc pfifo_fast state UP qlen 1000      link/ether 00:0c:29:02:4b:f5 brd ff:ff:ff:ff:ff:ff      inet 192.168.56.11/24 brd 192.168.56.255 scope global eth0      inet6 fe80::20c:29ff:fe02:4bf5/64 scope link       valid_lft forever preferred_lft forever  ifconfig eth0 | awk 'NR==2' | sed 's#^.*r:##g' | sed 's#Bc.*##g'  ifconfig eth0 | awk -F '[: ]+' 'NR==2{print $4}'  ifconfig eth0 | sed -n 2p | sed -r 's#(.*addr:)|(Bc.*$)##g'  # ★★★  ip a s eth0 | awk -F '[ /]+' 'NR==3{print $3}'  ip a s eth0 | sed -n 3p   | sed 's#^.*t ##g' | sed 's#/.*$##g'  ip a s eth0 | sed -n 3p   | sed -r 's#^.*t |/.*$##g'  ip a s eth0 | sed -n 3p   | sed -r 's#(^.*t )|(/.*$)##g'  ip a s eth0 | awk 'NR==3' | sed -r 's#(^.*t )|(/.*$)##g'  # 反向引用方法取IP  ifconfig eth0 | awk 'NR==2' | sed -r 's#(^.*addr:)(.*)(Bca.*$)#\2#g'  ifconfig eth0 | awk 'NR==2' | sed -r 's#^.*addr:(.*)Bca.*$#\1#g'  ifconfig eth0 | awk 'NR==2' | sed -r 's#(^.*addr:)(.*)(  Bca.*$)#\2#g' | cat -A  # ★★★  ip a s eth0   | awk 'NR==3' | sed -r 's#(^.*t )(.*)(/.*$)#\2#g'  ip a s eth0 | sed -n '3p' | sed 's#inet#oldboy#g'  ip a s eth0 | sed -n '3s#inet#oldboy#gp'  ip a s eth0 | sed -nr '3s#(^.*t )|(/.*$)##gp'  # hostname加参数直接取得  hostname -I  hostname -i (需配置域名解析)  ## 取出IP地址小结      1. awk 指哪打哪      2. sed 使用正则      3. sed 反向引用

题目2 取出stat /etc/hosts权限

[root@as4k /as4k]# stat /etc/hosts | nl

1 File: `/etc/hosts'

2 Size: 179 Blocks: 8 IO Block: 4096 regular file

3 Device: 803h/2051d Inode: 915740 Links: 2

4 Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)

5 Access: 2018-08-01 19:41:38.662386294 +0800

6 Modify: 2018-07-25 14:48:45.037907762 +0800

7 Change: 2018-07-25 14:48:45.045908338 +0800

#解答:  stat /etc/hosts | awk 'NR==4' | awk -F "[(/]"  '{print $2}'  stat /etc/hosts | awk -F '[0/]' 'NR==4{print $2}'  stat /etc/hosts | sed -nr '4s#(^Access: \(0)|(/.*$)##gp'  stat /etc/hosts | awk -F '[(/]' 'NR==4{print $2}'  stat /etc/hosts | sed -nr '4s#(^Access: \(0)(.*)(/-.*$)#\2#gp'  stat /etc/hosts | sed -nr '4s#(^Access: \()(.*)(/-.*$)#\2#gp'  stat /etc/hosts | awk 'NR==4' | sed -r 's#^.*\(([0-9]+).*$#\1#g'  stat /etc/hosts | sed -nr '4s#^.*\(([0-9]+).*$#\1#gp'  stat /etc/hosts | sed -nr '4s#^.*0([0-9]+).*$#\1#gp'  stat oldboy.txt | awk 'NR==4' | awk -F "[(/]"  '{print $2}'  [root@as4k /as4k]# stat -c %A /etc/hosts  -rw-r--r--  [root@as4k /as4k]# stat -c %a /etc/hosts  644  此题心得:      有时想要的东西在命令的结果里，可以考虑查找命令的帮助。

题目3 三剑客过滤空行

已知/oldboy/test.txt文件内容为：

oldboy

xizi

xiaochao

请问如何把文件中的空行过滤掉（要求命令行实现）。

[root@as4k /oldboy]# cat -nA test.txt

1 oldboy$

2 $

3 xizi$

4 $

5 xiaochao$

解答:  grep -v '^$' test.txt  sed '/^$/d'  test.txt  (按行为单位删除)  awk '!/^$/'  test.txt  sed -n '/^$/!p' test.txt

!在awk sed find 命令中都表示取反。

[root@as4k /oldboy]# grep -v '^$' test.txt   oldboy  xizi  xiaochao  [root@as4k /oldboy]# awk '!/^$/' test.txt   oldboy  xizi  xiaochao  [root@as4k /oldboy]# sed '/^$/d' test.txt   oldboy  xizi  xiaochao

题目4 三剑客取反过滤

已知/oldboy/ett.txt文件内容为：

oldboy

olldboooy

test

请使用grep或egrep正则匹配的方式过滤出前两行内容

[root@as4k /oldboy]# cat ett.txt

oldboy

olldboooy

test

解答:

grep -v test ett.txt  sed '/test/d' ett.txt  sed -n '/test/!p' ett.txt  awk '!/test/' ett.txt  grep  -o 'o.*y' ett.txt  egrep 'oldboy|olldboooy' ett.txt  egrep 'ol+dbo+y' ett.txt

三剑客过滤小结

grep 过滤显示执行过程-o 上色

sed 过滤替换修改文件

awk 过滤取列-F 计算统计

题目5 目录的硬链接

linux下通过mkdir命令创建一个新目录/oldboy/ett，

ett的硬链接数是多少，为什么？

[root@as4k /oldboy]# ls -lidh ett ett/. ett/oldboy/..

664237 drwxr-xr-x 3 root root 4.0K Aug 2 01:39 ett

664237 drwxr-xr-x 3 root root 4.0K Aug 2 01:39 ett/.

664237 drwxr-xr-x 3 root root 4.0K Aug 2 01:39 ett/oldboy/..

[root@as4k /oldboy]# tree

├── ett

│ ├── oldboy

│ └── oldboy2

├── ett.txt

└── test.txt

3 directories, 2 files

[root@as4k /oldboy]# ls -lidh ett ett/. ett/oldboy/.. ett/oldboy2/..

664237 drwxr-xr-x 4 root root 4.0K Aug 2 01:43 ett

664237 drwxr-xr-x 4 root root 4.0K Aug 2 01:43 ett/.

664237 drwxr-xr-x 4 root root 4.0K Aug 2 01:43 ett/oldboy/..

664237 drwxr-xr-x 4 root root 4.0K Aug 2 01:43 ett/oldboy2/..

可以看出，ett目录的硬链接目录数是4，扣除ett和ett/.这两个目录，还剩下

两个目录是其兄弟目录。因此通过查看目录的硬链接数也可也反推，目录中子目录的

个数。

# 过滤目录中子目录的个数  [root@as4k /oldboy]# ls -l /etc | grep '^d' | wc -l  77  [root@as4k /oldboy]# ls -lidh /etc/  915713 drwxr-xr-x. 79 root root 4.0K Jul 29 00:37 /etc/

简单显示系统时间和日历

[root@as4k /oldboy]# date

Thu Aug 2 01:58:52 CST 2018

[root@as4k /oldboy]# cal

August 2018

Su Mo Tu We Th Fr Sa

1 2 3 4

5 6 7 8 9 10 11

12 13 14 15 16 17 18

19 20 21 22 23 24 25

26 27 28 29 30 31

按照要求的格式显示日期

示例

1 显示年月日

[root@as4k /oldboy]# date +%F

2018-08-02

2 显示时分秒

[root@as4k /oldboy]# date +%T

15:27:10

3 显示年月日

[root@as4k /oldboy]# date +%Y.%m.%d

2018.08.02

[root@as4k /oldboy]# date +%Y#%m#%d

2018#08#02

[root@as4k /oldboy]# date +%Y%m%d

20180802

4 显示时分秒

[root@as4k /oldboy]# date +%H%M%S

15_29_29

[root@as4k /oldboy]# date +%H:%M:%S

15:29:36

5 显示今天日期

[root@as4k /oldboy]# date

Thu Aug 2 15:29:59 CST 2018

6 格式化显示今天日期

[root@as4k /oldboy]# date +%F\ %T

2018-08-02 15:30:42

7 显示今天是周几

[root@as4k /oldboy]# date +%w

8 显示1天前

[root@as4k ~]# date +%F\ %T

2018-08-02 16:04:35

[root@as4k ~]# date -d '-1 day' +%F\ %T

2018-08-01 16:04:36

9 显示5天后

[root@as4k ~]# date +%F\ %T

2018-08-02 16:06:07

[root@as4k ~]# date -d '+5 day' +%F\ %T

2018-08-07 16:06:08

10 18年前

[root@as4k ~]# date +%F\ %T

2018-08-02 16:07:10

[root@as4k ~]# date -d '-18 year' +%F\ %T

2000-08-02 16:07:11

抽象

date [OPTION]... [+FORMAT]

Display the current time in the given FORMAT

-d, --date=STRING

Display time described by string STRING,

as opposed to the default, which is 'now'.

可接受类型类似如下:

+1 year 1年后

-1 year 1年前

+3 day 3天后

-3 day 3天前

month, year(s), day(s), week

FORMAT controls the output. Interpreted sequences are:

%F     full date; same as %Y-%m-%d  %T     time; same as %H:%M:%S  %Y     year  %m     month (01..12)  %d     day of month (e.g, 01)  %H     hour (00..23)  %M     minute (00..59)  %S     second (00..60)

Relative items in date strings