36

Linux 下使用cut命令，实现更好切分数据 - 技术小黑屋

 4 years ago
source link: https://droidyue.com/blog/2020/04/25/linux-cut-command/?
Go to the source link to view the article. You can view the picture content, updated content and better typesetting reading experience. If the link is broken, please click the button below to view the snapshot at that time.

cut是什么

  • 一个Unix终端命令
  • 切割行内容，并进行标准输出
  • 可以按照字节，字符，分隔符进行切分

能有什么用

我们举一个简单的例子（非全部示例）来描述cut有什么用，可以做什么

简洁输出，去除干扰冗余信息

比如这个日志，可能会出现折行，另外假设04-19 18:26:55.605 22750 22883 W这些列的信息属于干扰信息

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

04-19 18:26:55.605 22750 22883 W System.err: java.lang.NoSuchFieldException
04-19 18:26:55.605 22750 22883 W System.err:  at com.xiaomi.push.au.a(Unknown Source:16)
04-19 18:26:55.605 22750 22883 W System.err:  at com.xiaomi.push.au.a(Unknown Source:4)
04-19 18:26:55.605 22750 22883 W System.err:  at com.xiaomi.push.service.z.a(Unknown Source:880)
04-19 18:26:55.605 22750 22883 W System.err:  at com.xiaomi.push.service.z.a(Unknown Source:188)
04-19 18:26:55.605 22750 22883 W System.err:  at com.xiaomi.push.service.p.a(Unknown Source:821)
04-19 18:26:55.605 22750 22883 W System.err:  at com.xiaomi.push.service.p.a(Unknown Source:605)
04-19 18:26:55.605 22750 22883 W System.err:  at com.xiaomi.push.service.p.a(Unknown Source:11)
04-19 18:26:55.605 22750 22883 W System.err:  at com.xiaomi.push.service.d.a(Unknown Source:46)
04-19 18:26:55.605 22750 22883 W System.err:  at com.xiaomi.push.service.ak.b(Unknown Source:50)
04-19 18:26:55.605 22750 22883 W System.err:  at com.xiaomi.push.service.ak.a(Unknown Source:10)
04-19 18:26:55.605 22750 22883 W System.err:  at com.xiaomi.push.service.XMPushService$c.a(Unknown Source:8)
04-19 18:26:55.605 22750 22883 W System.err:  at com.xiaomi.push.service.XMPushService$i.run(Unknown Source:37)
04-19 18:26:55.605 22750 22883 W System.err:  at com.xiaomi.push.service.g$c.run(Unknown Source:175)
04-19 18:27:24.787 23660 23685 W System.err: load vdr indoor lib success.

使用cut 我们可以实现删除上面的冗余信息

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

adb logcat | grep "System.err" --line-buffered | cut -d " " -f 6-
System.err: java.lang.NoSuchFieldException
System.err:   at com.xiaomi.push.au.a(Unknown Source:16)
System.err:   at com.xiaomi.push.au.a(Unknown Source:4)
System.err:   at com.xiaomi.push.service.z.a(Unknown Source:880)
System.err:   at com.xiaomi.push.service.z.a(Unknown Source:188)
System.err:   at com.xiaomi.push.service.p.a(Unknown Source:821)
System.err:   at com.xiaomi.push.service.p.a(Unknown Source:605)
System.err:   at com.xiaomi.push.service.p.a(Unknown Source:11)
System.err:   at com.xiaomi.push.service.d.a(Unknown Source:46)
System.err:   at com.xiaomi.push.service.ak.b(Unknown Source:50)
System.err:   at com.xiaomi.push.service.ak.a(Unknown Source:10)
System.err:   at com.xiaomi.push.service.XMPushService$c.a(Unknown Source:8)
System.err:   at com.xiaomi.push.service.XMPushService$i.run(Unknown Source:37)
System.err:   at com.xiaomi.push.service.g$c.run(Unknown Source:175)

按照字节切分(cut -b)

按照字节位置切分

1
2
3
4
5
6
7
8
9
10
11
12
13
14

# 取第一个字节
pi@raspberrypi:~ $ echo "abcdef" | cut -b 1
a


# 取第二个字节
pi@raspberrypi:~ $ echo "abcdef" | cut -b 2
b


# 从1开始，0会报错
pi@raspberrypi:~ $ echo "abcdef" | cut -b 0
cut: byte/character positions are numbered from 1
Try 'cut --help' for more information.

按照字节区间切分

1
2
3
4
5
6
7
8
9
10
11

#1到2字节位置切分
pi@raspberrypi:~ $ echo "abcdef" | cut -b 1-2
ab

# 限定区间起始位置，不限定结束位置
pi@raspberrypi:~ $ echo "abcdef" | cut -b 1-
abcdef

# 限定区间结束位置，但不限定起始位置
pi@raspberrypi:~ $ echo "abcdef" | cut -b -5
abcde

按照字节多个位置切分

1
2

pi@raspberrypi:~ $ echo "abcdef" | cut -b 1,3,5
ace

按照字符区分

当我们按照字符进行切分时，会遇到一些问题，比如出现中文的时候（一个中文占用三个字节）

1
2
3
4
5
6
7

# 异常出现
echo "小黑屋" | cut -b 1
�

##必须限定满足正确的开始和结束位置
echo "小黑屋" | cut -b 1-3
小

但是如果中英文并存，就比较麻烦了，好在有按照字符切分的方法(cut -c)

1
2
3
4
5
6
7
8
9
10
11
12
13
14

echo "abcd技术小黑屋ef" | cut -c 7
小

echo "abcd技术小黑屋ef" | cut -c 7-9
小黑屋

echo "abcd技术小黑屋ef" | cut -c 7,8,9
小黑屋

echo "abcd技术小黑屋ef" | cut -c 5-
技术小黑屋ef

echo "abcd技术小黑屋ef" | cut -c -9
abcd技术小黑屋

按照分隔符切分（cut -d ）

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

echo "A|BC|DEF|GHIJ" |  cut -d "|" -f 1
A

echo "A|BC|DEF|GHIJ" |  cut -d "|" -f 2
BC

echo "A|BC|DEF|GHIJ" |  cut -d "|" -f 3
DEF

# 区间，限定开始位置
echo "A|BC|DEF|GHIJ" |  cut -d "|" -f 1-
A|BC|DEF|GHIJ

#区间，限定结束位置
echo "A|BC|DEF|GHIJ" |  cut -d "|" -f -3
A|BC|DEF

# 区间，限定开始和结束位置
echo "A|BC|DEF|GHIJ" |  cut -d "|" -f 1-2
A|BC

#提供多个位置
echo "A|BC|DEF|GHIJ" |  cut -d "|" -f 1,2
A|BC
  • 上面为了示例简单实用了echo 加管道的方式
  • 上面所有的例子，都可以实用类似加文件的形式
  • 比如cut -b 1 test_cut_file.txt,cut -c 1 test_cut_file.txt,cut -d "|" -f 1 test_cut_file.txt

report

Recommend

About Joyk


Aggregate valuable and interesting links.
Joyk means Joy of geeK