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This article mainly explains "what are the common text filtering commands in Linux". The content in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn what are the common text filtering commands in Linux.

01 cat command

Usually used to display the contents of a text file

It is generally used to view short text files because of their limited buffer

The-s option can be used to merge extra blank lines in the file, and multiple blank lines will be compressed into a single blank line.

The-n option displays the line number

The-b option skips the number of blank lines and displays the line numbers of non-blank lines

Cat can be used to assign standard input to standard output without any parameters.

02 more command

Can be used to view the contents of a text file on a split screen.

When the contents of the file have been checked on one screen, it can be viewed separately, and the last line will show the prompt of more.

The enter key scrolls back one line and the space scrolls one screen.

Search is also supported in more, which is consistent with the search usage in vim

Press Q key to exit more automatically

You can add pipe symbols and more commands after some commands, and the results of the commands can be displayed on separate screens.

03 less command

Used to display the contents of a text file in separate screens

Less is more powerful than the more command

The enter key scrolls back one line and the space scrolls one screen.

You can also use the upper and lower keys to check, more cannot be rolled back

Search operations are also supported

More will exit automatically after displaying the contents of the file; less will not, you need to use the Q key.

In the process of viewing, you can also call other shell instructions, the same as the bottom line mode of vim

04 grep command

Is a long matching instruction that matches the text we enter and searches for matching lines in the file

# grep "root" / ets/passwd

Regular expressions are supported in matching patterns

# grep-n "fs$" / proc/filesystem / / search for lines ending in fs

05 head command

Used to display the high-quality content of the file, the first 10 lines of the file are displayed by default

# head / etc/httpd/conf/httpd.conf

The-n option specifies the number of rows displayed

It is important to display the high quality content of some very large files.

Can display high-quality content of multiple files

06 tail command

Used to display the tail content of a given text file, and the tail 10 lines are displayed by default

# tail filename

The-n option specifies the number of lines that are displayed

-f can dynamically follow the changes at the end of the file, and this option is often used to monitor system log files.

07 wc command

Used to count the number of lines, words and bytes in a text file

# wc / etc/passwd

44 72 2102 / etc/passwd

# wc-l / etc/passwd / / count the number of lines in a separate file

# ps-ef | grep gnome | wc-l / / Statistics on the number of gnome processes in the current system

# wc

Then enter part of the content, and press Ctrl+d to count the text information we just entered.

08 uniq command

Used to filter duplicate lines in the file without changing the contents of the file

Requires that the text to be filtered is already sorted

First use the sort command to sort, and then use the uniq command # sort file | uniq

The-c option can count the number of duplicate rows

09 cut command

Used to display the columns specified in the text file

# cut-f 1-d "" / etc/fstab / / split by spaces to show part 1

# cut-c-15 / proc/net/arp / / displays the first 15 characters of each column, that is, the IP address

10 sort command

Used to sort text

# sort file

Just sorting the content in file for output does not change the content of file.

The-o option can be exported to the specified file

# sort file-o result

You can also use the redirect function to save the sort results to a file

11 join command

Used to merge the same fields in a given file, requiring the file to be sorted

# cat math

Tom 90

Jim 91

# cat english

Jim 95

Tom 96

# sort math > math.sorted

# sort english > english.sorted

# join math.sorted english.sorted

Jim 91 95

Tom 90 96

12 split command

Used to divide a given file into several small files

# split acess_log

A lot of small files are generated, each of which defaults to 1000 lines

The-l option specifies the number of lines for the split file size

13 unexpand command

Used to convert extra space characters in a file into tabs

# cat test.txt

Liuli zhangsan

# unexpand-t 10 test.txt

Liuli zhangsan

-t converts the specified number of whitespace into a Tab key

14 tr command

Is a character processing tool that replaces and deletes individual characters in a given text, not a string processing tool

# tr dev xyz

The sed command can replace strings

# tr Amurz Amurz

# tr-d angi

Zhslswwu

# echo $PATH

/ opt/arm-2009q3/bin:/usr/lib/qt4/bin:/usr/lib/qt-3.3/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin:/home/beangr/bin

# echo $PATH | tr ":"\ n" / / replace the: in the result with a newline character

/ opt/arm-2009q3/bin

/ usr/lib/qt4/bin:/usr/lib/qt-3.3/bin

/ usr/local/bin

/ usr/bin

/ bin

/ usr/local/sbin

/ usr/sbin

/ sbin

/ home/beangr/bin

15 tee command

Used to read data from standard input, save it to a specified file, and output it to standard output

# cat / etc/fstab | tee file1 file2 file3

/ * Save to file1,file2,file3 while normal output to standard output * /

16 tac command

Used to display the contents of text in reverse order in units of behavior

Tac is a counter-instruction of cat

17 spell command

Is a spell check command in Linux that can check the spelling of the text in a file in terms of words and print out misspelled words

# spell file

18 paste command

Used for merging multiple text files to list as units

# cat t1.txt

Name math java

Tom 100 70

Jim 80 88

# cat t2.txt

C++

ninety

eighty-nine

# paste t1.txt t2.txt

Name math java C++

Tom 100 70 90

Jim 80 88 89

If you need to save the results to a file, you need to use redirection

19 diff command

Used to compare the differences between two files

# diff file1 file2

The diff command is often used to generate patch files.

# diff-Nur file1 file2 > a.patch

20 cmp command

Used to compare the types of two files, which can be any type of file

Will show where it starts to be different.

# cmp file1 file2

# cmp / bin/ls / bin/mail

# cmp file1 file1 / / compare two identical files with no output

21 look command

Used to display lines in a file that begin with a specified string, requiring that the text file be ordered

# cat t1.txt

Name math java

Zhang 100 70

Lisi 70 88

Wang 100 70

Zhang 100 70

# sort t1.txt > t1.txt.sorted

# look zhang t1.txt

Zhang 100 70

# look zhang t1.txt.sorted

Zhang 100 70

Zhang 100 70

# look hello / / you can query our dictionary and all words containing hello will be displayed.

When you install the look command, two dictionary files are installed

22 ispell command

You can check the Chinese and English spelling errors in the document and give tips for correction.

# cat test.txt

Yyear month hppy

# the result of ispell test.txt / / modification will be saved to a file

23 fold command

Used to control the width of the screen when the contents of the file are displayed

# fold-w 20 / etc/fstab / / specify a width of 20 characters

The content of the newline does not mean that the text is multi-line, it is just multi-line display.

24 fmt command

Used to optimize the text format of the contents of a text file

# fmt-u / etc/fstab / / will compress the displayed spaces

25 expand command

Used to convert tabs in a file to space characters

# cat t1.txt

Hello world

Hello Linux

# expand-t 20 t1.txt

Hello world

Hello Linux

Reciprocal with unexpand

26 col command

Control information used to filter the output of other instructions

# cat mytest | col > mytest3

27 colm command

Used to delete the specified column in the file (in characters)

# colm 20

The original content will not change.

# colm 20 50

28 comm command

Used to compare sorted files in behavioral units

# cat chengji1

Wangwu 90

Lisi 60

Zhangsan 80

# cat chengji2

Wangwu 90

Zhangsan 80

Lisi 70

# sort chengji1 > chengji1-1

# sort chengji2 > chengji2-2

# comm chengji1-1 chengji2-2

29 csplit command

Used to split a large file into small files in behavioral units

# csplit test.txt 300

/ * split into two files from 300 lines * /

30 diff3 command

Used to compare the differences of 3 files and show their differences

# diff3 file1 file2 file3

31 diffstat command

Used to count the output of diff instructions

# diff a.patch

32 printf command

Used to format and output the results to standard output, very similar to the printf function in C language

# printf "% s\ t% s\ n"Hello"world"

Hello world

33 pr command

Used to convert a text file into a file suitable for printing, you can divide the file into multiple pages and add a print title

# pr test.txt > test.txt.print

34 od command

An octal, hexadecimal, or other format encoded byte used in an output file, usually used to display characters that cannot be displayed directly on a terminal.

# od-tcx1 test.txt

# cat test.txt

Hello world

35 rev command

It is used to output the text content of the file in reverse order of characters in behavior units.

# cat test.txt

Hello world

I love linux!

# rev test.txt

Dlrow olleh

! xunil evol I

Thank you for your reading, these are the contents of "what are the common text filtering commands in Linux". After the study of this article, I believe you have a deeper understanding of what the common text filtering commands in Linux have, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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