Linux 命令： cut 和 tr

1. 写在前面

本文主要介绍：Linux “cut “和 “tr” 命令行实用程序概述；

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2. Linux 命令：cut

“cut” 命令是一种命令行工具，允许我们剪切指定文件或管道数据的部分内容，并将结果打印到标准输出。

root@dev:~# man cut
-------------------------------------------------------
NAME
       cut - remove sections from each line of files
SYNOPSIS
       cut OPTION... [FILE]...
... ...       
-b, --bytes=LIST
    select only these bytes
-c, --characters=LIST
    select only these characters
-d, --delimiter=DELIM
    use DELIM instead of TAB for field delimiter
... ...

下面是一个文本文件：让我们看看如何操作下面的文本文件，以根据需要打印输出。

test.txt:

Nov 15 00:13:08 dev com.apple.xpc.launchd[1] (com.apple.mdworker.shared.10000000-0000-0000-0000-000000000000[1938]): Service exited due to SIGKILL | sent by mds[98]
Nov 15 00:13:15 dev com.apple.xpc.launchd[1] (com.apple.mdworker.shared.01000000-0000-0000-0000-000000000000[1936]): Service exited due to SIGKILL | sent by mds[98]
Nov 15 00:13:15 dev com.apple.xpc.launchd[1] (com.apple.mdworker.shared.06000000-0200-0000-0000-000000000000[1935]): Service exited due to SIGKILL | sent by mds[98]
Nov 15 00:13:15 dev com.apple.xpc.launchd[1] (com.apple.mdworker.shared.04000000-0200-0000-0000-000000000000[1939]): Service exited due to SIGKILL | sent by mds[98]
Nov 15 00:13:41 dev com.apple.xpc.launchd[1] (com.apple.mdworker.shared.05000000-0600-0000-0000-000000000000[1940]): Service exited due to SIGKILL | sent by mds[98]
Nov 15 00:13:41 dev com.apple.xpc.launchd[1] (com.apple.mdworker.shared.08000000-0100-0000-0000-000000000000[1941]): Service exited due to SIGKILL | sent by mds[98]
Nov 15 00:13:41 dev com.apple.xpc.launchd[1] (com.apple.mdworker.shared.0D000000-0200-0000-0000-000000000000[1917]): Service exited due to SIGKILL | sent by mds[98]
Nov 15 00:13:41 dev com.apple.xpc.launchd[1] (com.apple.mdworker.shared.0E000000-0400-0000-0000-000000000000[1937]): Service exited due to SIGKILL | sent by mds[98]

2.1 按字符范围打印

在一定字符范围内打印输出：

范围：1 – 5

root@dev:~# cut -c 1-5 test.txt 
-------------------------------------------------------
Nov 1
Nov 1
Nov 1
Nov 1
Nov 1
Nov 1
Nov 1
Nov 1

范围：21 – 40

root@dev:~# cut -c 21-40 test.txt 
-------------------------------------------------------
com.apple.xpc.launch
com.apple.xpc.launch
com.apple.xpc.launch
com.apple.xpc.launch
com.apple.xpc.launch
com.apple.xpc.launch
com.apple.xpc.launch
com.apple.xpc.launch

范围：70 – end

root@dev:~# cut -c 76-  test.txt 
-------------------------------------------------------
00000-0000-0000-0000-000000000000[1938]): Service exited due to SIGKILL | sent by mds[98]
00000-0000-0000-0000-000000000000[1936]): Service exited due to SIGKILL | sent by mds[98]
00000-0200-0000-0000-000000000000[1935]): Service exited due to SIGKILL | sent by mds[98]
00000-0200-0000-0000-000000000000[1939]): Service exited due to SIGKILL | sent by mds[98]
00000-0600-0000-0000-000000000000[1940]): Service exited due to SIGKILL | sent by mds[98]
00000-0100-0000-0000-000000000000[1941]): Service exited due to SIGKILL | sent by mds[98]
00000-0200-0000-0000-000000000000[1917]): Service exited due to SIGKILL | sent by mds[98]
00000-0400-0000-0000-000000000000[1937]): Service exited due to SIGKILL | sent by mds[98]

2.2 按字段名打印

假设我们想根据字段从以下文件中提取数据。

test.txt:

NAME EMAIL PHONE ADDRESS
devid devid@text.com 0897663232 beijin,china
harry harry@text.com 0232323232 hangzhou,china
jane jane@text.com 0323213122 zhejiang,china

我们必须使用"-d = delimiter"选项（可以是一个字符，默认为 TAB）来分隔每个字段。然后，我们必须指定要打印的字段编号。

-d, --delimiter=DELIM   
-f, --fields=LIST 

>> cut -d ' ' -f1

在下面的演示中，我们使用空格（’ ‘）作为分隔符。

# 打印空格分割第1列
root@dev:~# cut -d ' ' -f1  test.txt 
-------------------------------------------------------
NAME
devid
harry
jane


# 打印空格分割第2列
root@dev:~# cut -d ' ' -f2 test.txt 
-------------------------------------------------------
EMAIL
devid@text.com
harry@text.com
jane@text.com

打印多个字段：打印第1、3列

root@jpzhang-dev:~# cut -d ' ' -f1,3 test.txt 
-------------------------------------------------------
NAME PHONE
devid 0897663232
harry 0232323232
jane 0323213122

使用逗号 (, ) 作为分隔符：

root@dev:~# echo "jane,jane@dev,12345678,china" | cut -d ','  -f1
--------------------------------------------------------------------
jane

root@dev:~# echo "jane,jane@dev,12345678,china" | cut -d ','  -f2
--------------------------------------------------------------------
jane@dev

root@dev:~# echo "jane,jane@dev,12345678,china" | cut -d ','  -f3
--------------------------------------------------------------------

12345678

3. Linux 命令：tr

Linux tr 命令用于转换或删除文件中的字符。
tr 指令从标准输入设备读取数据，经过字符串转译后，将结果输出到标准输出设备。

语法

tr [-cdst][--help][--version][第一字符集][第二字符集]  
tr [OPTION]…SET1[SET2]

具体参数：

>> man tr
--------------------------------------------------------------------
tr [OPTION]... SET1 [SET2]
# Options
-c, -C, --complement
    use the complement of SET1
-d, --delete
    delete characters in SET1, do not translate
-s, --squeeze-repeats
    replace each sequence of a repeated character that is listed in the last specified SET, with a single occurrence of that character
-t, --truncate-set1
    first truncate SET1 to length of SET2
...
...

参数说明：

⁃   -c, --complement：反选设定字符。也就是符合 SET1 的部份不做处理，不符合的剩余部份才进行转换  
⁃   -d, --delete：删除指令字符  
⁃   -s, --squeeze-repeats：缩减连续重复的字符成指定的单个字符  
⁃   -t, --truncate-set1：削减 SET1 指定范围，使之与 SET2 设定长度相等  
⁃   --help：显示程序用法信息  
⁃   --version：显示程序本身的版本信息

字符集合范围：

⁃   NNN 八进制值的字符 NNN (1 to 3 为八进制值的字符)
⁃   \ 反斜杠
⁃   a Ctrl-G 铃声
⁃   b Ctrl-H 退格符
⁃   f Ctrl-L 走行换页
⁃   n Ctrl-J 新行
⁃   r Ctrl-M 回车
⁃   t Ctrl-I tab键
⁃   v Ctrl-X 水平制表符
⁃   CHAR1-CHAR2 ：字符范围从 CHAR1 到 CHAR2 的指定，范围的指定以 ASCII 码的次序为基础，只能由小到大，不能由大到小。
⁃   [CHAR*] ：这是 SET2 专用的设定，功能是重复指定的字符到与 SET1 相同长度为止
⁃   [CHAR*REPEAT] ：这也是 SET2 专用的设定，功能是重复指定的字符到设定的 REPEAT 次数为止(REPEAT 的数字采 8 进位制计算，以 0 为开始)
⁃   [:alnum:] ：所有字母字符与数字
⁃   [:alpha:] ：所有字母字符
⁃   [:blank:] ：所有水平空格
⁃   [:cntrl:] ：所有控制字符
⁃   [:digit:] ：所有数字
⁃   [:graph:] ：所有可打印的字符(不包含空格符)
⁃   [:lower:] ：所有小写字母
⁃   [:print:] ：所有可打印的字符(包含空格符)
⁃   [:punct:] ：所有标点字符
⁃   [:space:] ：所有水平与垂直空格符
⁃   [:upper:] ：所有大写字母
⁃   [:xdigit:] ：所有 16 进位制的数字
⁃   [=CHAR=] ：所有符合指定的字符(等号里的 CHAR，代表你可自订的字符)

3.1 替换字符

替换字符：’H’ > ‘h’

root@dev:~# echo "Hello World" | tr 'H' 'h'
--------------------------------------------------------------------
hello World

替换字符：‘Ho’ > ‘xx’ 即 ‘H’ 或 ‘o’ 替换为 ‘x’

root@dev:~# echo "Hello World" | tr 'Ho' 'xx'
--------------------------------------------------------------------
xellx Wxrld

3.2 删除字符

# 删除 'H' 或 'o'
root@dev:~# echo "Hello World" | tr -d 'Ho'  
--------------------------------------------------------------------
ell Wrld

# 反选，除'Hdn'其他删除
root@dev:~# echo "Hello World" | tr -cd 'Hdn'
--------------------------------------------------------------------
Hd

# 反选，除数字外其他删除
root@dev:~# echo "Hello World 12345 " | tr -cd [:digit:]
--------------------------------------------------------------------
12345

# 反选，除字母外其他删除
root@dev:~# echo "Hello World 12345 " | tr -cd [:alpha:]
--------------------------------------------------------------------
HelloWorld

3.3 压缩字符

# 压缩指定重复字符
root@dev:~# echo "HHHHHHHHellooooo Woooorrrrrrrrrldddddddddddddddddd" | tr -s 'Hord' 
------------------------------------------------------------------------------------
Hello World

# 压缩重复字符，小写转换大写
root@dev:~# echo "Hello World" | tr -s [:lower:] [:upper:]
------------------------------------------------------------------------------------
HELO WORLD