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How to use cat text output commands in Linux? I believe that many inexperienced people are at a loss about this, so this article summarizes the causes and solutions of the problem. Through this article, I hope you can solve this problem.

The cat command is a text output command under linux, which is usually used to view the contents of a file.

I. function

Cat has three main functions:

1. Displays the entire file at once.

The code is as follows:

$cat filename

two。 Create a file from the keyboard.

The code is as follows:

$cat > filename

Only new files can be created, existing files cannot be edited.

3. Merge several files into one file.

The code is as follows:

$cat file1 file2 > file

The specific cat command format is as follows:

The code is as follows:

Cat [- AbeEnstTuv] [--help] [--version] fileName

Description: connect the file string to the basic output (screen or add > fileName to another file)

Parameters:

-n or-number numbering all output lines starting with 1

-b or-number-nonblank is similar to-n, except that blank lines are not numbered

When-s or-squeeze-blank encounters blank lines with more than two consecutive lines, replace them with blank lines of one line

-v or-show-nonprinting

Example:

The code is as follows:

Cat-n linuxfile1 > linuxfile2

Add the line number to the linuxfile1 file and enter it into the linuxfile2 file.

The code is as follows:

Cat-b linuxfile1 linuxfile2 > > linuxfile3

Append the contents of linuxfile1 and linuxfile2 files to linuxfile3 after adding line numbers (blank lines are not added).

Example:

Add the line number to the linuxfile1 file and enter it into the linuxfile2 file.

The code is as follows:

Cat-n linuxfile1 > linuxfile2

Append the contents of linuxfile1 and linuxfile2 files to linuxfile3 after adding line numbers (blank lines are not added).

The code is as follows:

Cat-b linuxfile1 linuxfile2 > > linuxfile3

The code is as follows:

Cat / dev/null > / etc/test.txt

This is emptying / etc/test.txt file content

We often see something like cat sdkjflk in linux shell scripts.

> asdlfj

> HHH

The "HHH" here replaces the function of "EOF". The result is the same.

Quote

The code is as follows:

# cat iii.txt

Sdlkfjksl

Sdkjflk

Asdlfj

4. Non-scripting

If not in the script, we can use Ctrl-D to output the identity of the EOF

The code is as follows:

# cat > iii.txt

Skldjfklj

Sdkfjkl

Kljkljklj

Kljlk

Ctrl-D

Results:

Quote

The code is as follows:

# cat iii.txt

Skldjfklj

Sdkfjkl

Kljkljklj

Kljlk

IV. Demonstration of basic usage examples

Example 1

The code is as follows:

[root@localhost ~] # cat test # normal output

1111111111

2222222222

3333333333

[root@localhost ~] # cat-n test # begins with a line number

1 1111111111

two

three

4 2222222222

five

6 3333333333

[root@localhost ~] # cat-E test # ends with $

1111111111 $

$

$

2222222222 $

$

3333333333 $

[root@localhost ~] # cat-s test # more than two blank lines are merged into one

1111111111

2222222222

3333333333

[root@localhost ~] # cat-ns test # go to blank lines and add line numbers

1 1111111111

two

3 2222222222

four

5 3333333333

Example 2

The code is as follows:

[zhangy@BlackGhost awksed] $cat x * > google_bak.tar.gz # merge files

Example 3

The code is as follows:

# cat > aa # enter the content from the keyboard to the file, enter to save, and exit Ctrl+z

4234234

234234

^ Z

[4] + Stopped cat > aa

# cat file1 file2 > file # merge two files into one

Example 4

The code is as follows:

# cat test.tar.gz_?? > test.tar.gz # you can use the cat command to merge multiple compressed packages that are cut into one

# tar-xvzf test.tar.gz # and then extract it with the tar command

After reading the above, have you mastered how to use cat text output commands in Linux? If you want to learn more skills or want to know more about it, you are welcome to follow the industry information channel, thank you for reading!

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