Shell special symbol, cut, sort, WC, uniq, tee, TR, split command

* Represents 0 or more arbitrary characters

[[email protected] ~]# ls *txt

11.txt 1.txt 22.txt 2.txt aa.txt a.txt

？ Represents only one arbitrary character

Whether it's a number or a letter, as long as it matches a single character.

[email protected] ~]# ls?. Txt

1.txt 2.txt a.txt B.txt

[[email protected] ~]# ls? txt

ls: unreachable? txt: no file or directory

Comment Symbol #, after which the contents of this symbol will be ignored

[Email protected] ~]# a=123 #456

[Email protected] ~]# echo $a

123

The caret character \, this character reverts the following special symbol (such as *) to normal characters.

[Email protected] ~]# ls-ld test*

Drwxr-xr-x. 2 root root 6 November 14:06 test

[Email protected] ~]# ls-ld test\*

LS: Unable to access test*: No file or directory

Pipe symbol | , which is the function of the output of the preceding command as input to the subsequent command. Not all commands can be used in pipe characters, common commands: Cat, less, head, tail, grep, cut, sort, WC, uniq, tr, split, SED, awk, and so on.

[email protected] ~]# Cat 1.txt | Wc-l

1

Cut command

The Cut command is used to intercept a field.

The format is: cut-d ' delimiter '-[fc]n,n is a number.

-D: followed by a delimiter, delimited by single quotation marks.

-F: The next section is followed by the number of blocks

-C: followed by the first few characters

(-C does not need and-f,-d need-f)

[Email protected] ~]# head-5/etc/passwd | Cut-d ': '-f 1-4

root:x:0:0

Bin:x:1:1

Daemon:x:2:2

Adm:x:3:4

Lp:x:4:7

-D colon is delimiter, and-F 1-4 intercepts 1-4 segments

[Email protected] ~]# head-5/etc/passwd | Cut-c 1-4

Root

Bin

Daem

Adm:

Lp:x

The-C can be 1 digits or interval 1-4, or multiple numeric n1,n2,n3 (separated by commas).

[Email protected] ~]# head-5/etc/passwd | Cut-c 1,6,8

Rx0

B::

Dnx

A::

L47

Sort command

The sort command is used as sorting.

The format is: Sort-[-t delimiter] [-kn1,n2] [-nru] n1,n2 is a number.

-T: The following is the same as the split character, function and cut-d.

-N: Indicates the use of pure numeric sorting.

-r: Indicates reverse ordering.

-U: Indicates removal of duplicates.

-KN1,N2: Indicates n1-n2 interval ordering, or write-only-kn1.

If sort does not have any options, the first character is compared to the ASCII values one at a time, and finally the characters are output in ascending order.

[Email protected] ~]# Head-n 5/etc/passwd | Sort

a Dm:x:3:4:adm:/var/adm:/sbin/nologin

b In:x:1:1:bin:/bin:/sbin/nologin

D Aemon:x:2:2:daemon:/sbin:/sbin/nologin

L P:x:4:7:lp:/var/spool/lpd:/sbin/nologin

R Oot:x:0:0:root:/root:/bin/bash

The-t option is followed by a delimiter, and the-K option follows a number to sort the string for the first range, and the-N option means to sort using a pure number.

[email protected] ~]# head-n 5/etc/passwd | sort-t ': '-K 3-n #将第三段的字符用纯数字排序.

root:x: 0 : 0:root:/root:/bin/bash

bin:x: 1 : 1:bin:/bin:/sbin/nologin

daemon:x: 2 : 2:daemon:/sbin:/sbin/nologin

adm:x: 3 : 4:adm:/var/adm:/sbin/nologin

lp:x: 4 : 7:lp:/var/spool/lpd:/sbin/nologin

The-K option is followed by the number n1,n2 to sort the strings within the region of N1 and N2, and the-R reverses the sort.

[email protected] ~]# head-n 5/etc/passwd | sort-t ': '-K 3,5-r #将第三至五段区间内的字符串进行反向排序.

lp:x: 4 : 7:lp:/var/spool/lpd:/sbin/nologin

adm:x: 3 : 4:adm:/var/adm:/sbin/nologin

daemon:x: 2 : 2:daemon:/sbin:/sbin/nologin

bin:x: 1 : 1:bin:/bin:/sbin/nologin

root:x: 0 : 0:root:/root:/bin/bash

WC command

The WC command is used to count the number of lines, characters, or words of a document.

-L count rows

-W Statistic Word number

-M statistic character number

WC does not follow any parameters directly with the document will be the number of rows, words, characters, sequentially output.

[Email protected] ~]# WC/ETC/PASSWD

1128/etc/passwd

[Email protected] ~]# wc-l/etc/passwd

24/etc/passwd

[Email protected] ~]# wc-w/etc/passwd

44/etc/passwd

[Email protected] ~]# wc-m/etc/passwd

1128/etc/passwd

Uniq command

The Uniq command is used to delete duplicate rows, common option-C, which represents the number of rows counted and writes the number of rows in front.

Before using Uniq, you have to sort the files first (sort), otherwise it doesn't work.

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Tee command

Tee command after the root file name, acting similar to output redirection (>), it can also write to the following file, also displayed on the screen. Commonly used for pipe characters | After.

-A: Use Append mode when redirecting to files

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Use the-a parameter. Additional.

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TR command

The TR command is used to replace characters and is commonly used to handle special symbols appearing in documents.

-D means to delete a character.

[Email protected] ~]# echo "Huangdalinux" | Tr ' A ' a '

Huangdalinux #将字符串中的a替换成A

[Email protected] ~]# echo "Huangdalinux" | Tr ' an '

Huangdalinux #将字符串中的a和n替换成A和N

[Email protected] ~]# echo "Huangdalinux" | Tr ' A-Z ' A-Z

Huangdalinux #将字符串中的小写字母替换成大写字母

Delete a character in a string by using the-D parameter

[Email protected] ~]# echo "Huangdalinux" | Tr-d ' a '

Hungdlinux

[Email protected] ~]# echo "Huangdalinux" | Tr-d ' A,u '

Hngdlinx

S

Plit command

The split command is used to cut documents, and the common options are-B and-L

-B: Indicates that the document is split by size, and the default unit is byte.

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-L: Indicates that the document is divided by the number of rows.

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Specifies the destination file name.

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The special symbol $, used as the identifier for the preceding variable.

Special symbols;. If you want to run two or more commands in a row, you need to add a sign between the commands.

Special symbol ~. Represents the user's home directory, the root user is/root, and the normal user is the/home/user name/

Special Symbols &. You can put a command in the background to execute. After the command is received.

Output redirect , output redirect Append >>, error redirect 2>, error redirect append 2>>, correct and error output both redirect &>. correct and error outputs both redirect append &>>

Brackets [], in parentheses, are character combinations that represent any one of the character combinations and can be a range.

Special symbols && and | |

Command1;command2

When used, the Command2 is executed regardless of whether or not the Command1 is performing successfully.

Command1&&command2

When && is used, Command2 is executed only if Command1 is executed successfully.

command1| | Command2

Use | | , Command1 execution succeeds, Command2 does not execute, otherwise execution command2, that is, Command1 and Command2 always have a command to execute.

This article is from the "Network Management Learning Road" blog, please be sure to keep this source http://754599082.blog.51cto.com/11510506/1982863

Shell special symbol, cut, sort, WC, uniq, tee, TR, split command