Detailed explanation of the cut command
The job of cut is to "cut", specifically, it is responsible for cutting data in files. The cut command cuts bytes, characters, and fields from each line of the file and outputs those bytes, characters, and fields.
1. Basic syntax
cut [Option parameters] filename
Description: The default delimiter is a tab character.
Options and parameters:
-d: Delimiter, divide the columns according to the specified delimiter. Use with -f
-f: divide a piece of information into segments based on the separating character of -d, and use -f to extract the meaning of the paragraph (column number, which column is extracted)
-c: Take out fixed character intervals in units of characters
-b: Split in bytes
2. Practical cases
Prepare data
[root@jiangnan data]$ touch
[root@jiangnan data]$ vim
dong shen
guan zhen
wo wo
lai lai
le le
- Cut the first column
[root@jiangnan data]# cut -d ' ' -f 1
dong
guan
wo
lai
le
[root@jiangnan data]#
Note that there are spaces in double quotes, because spaces should be used as separators.
- Cut the second and third columns
[root@jiangnan data]# cut -d ' ' -f 2,3
shen
zhen
wo
lai
le
[root@jiangnan data]#
Note that there is a space in front of the next three, because we wrote two spaces when preparing the data.
- Characters 5-8 of the cut
[root@jiangnan data]# cut -c 5-8
she
zhe
wo
lai
le
[root@jiangnan data]#
- Cut 2, 4, 6 bytes
[root@jiangnan data]# cut -b 2,4,6
ogs
unz
o o
a l
e e
[root@jiangnan data]#
It can be seen that bytes and characters are equivalent in pure English state。
- Cut contents before 6th byte
[root@jiangnan data]# cut -b -6
dong s
guan z
wo wo
lai l
le le
[root@jiangnan data]#
- Cut Chinese characters in strings
[root@jiangnan data]# echo "I love you China" | cut -c 2,3Love you[root@jiangnan data]# echo "I love you China" | cut -b 2,3
[root@jiangnan data]# echo "I love you China" | cut -d ' ' -f -2I love[root@jiangnan data]#
It is best to use -c (character) for cutting Chinese characters, and bytes (-b) cannot meet the requirements.
- Cut out guan in file
[root@jiangnan data]# cat | grep "guan" | cut -d " " -f 1
guan
[root@jiangnan data]#
- Select the system PATH variable value, and all paths after the first ":" start:
[root@jiangnan data]# echo $PATH
/usr/local/java/jdk1.8.0_161/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin
[root@jiangnan data]# echo $PATH | cut -d: -f 2-
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin
[root@jiangnan data]#
3. What are the defects and shortcomings of cut
If some fields in the file areSeveral spaces are spaced apart, then it will be a bit troublesome to use cut, becauseFor cut is only good at handling text content "in one character interval".
CUT command details
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