# Linux CAT command

## **  Uses of cat command.**

cat(concatenate) is one of the most basic commands in Linux operation systems. every programmer should know about the cat command. It can be used for doing a lot of things as mentioned below.


#### 1) Create a file 

The command is:       

 **$ cat > file1**

output:-

A new file with the name **file1** will be created. Now you can write in the new text file once you are finished writing in the file press **ctrl + d** to save and exit.

example:- **$ cat > file1 **
I am Advin Suryavanshi.
I am a student.
I am pursuing my bachelor of technology in computer science.
**ctrl + d**





#### 2) To view a  file

The command is: 

**$ cat file1**

output:-

This command is used to see the content of the file with the name **file1**.


#### 3) To view multiple files 

The command is: 

**$ cat file1 file2**

output:- 

This command is used to see the content of the file with the name **file1** and **file2**.


#### 4) To view the contents of a file with line numbers.

The command is: 

**$ cat -n file1**

output:-

It shows content with line numbers.

example: $ cat -n file1 

1 I am Advin Suryavanshi.

2 I am a student.

3 I am pursuing my bachelor of technology in computer science.


#### 5) To write in an already existing file.

The command is: 

**$cat >> file1**

 hello reader.

output:-

It Will append the text **"hello reader."** to the end of the **file1**.

so if we will now view the file using **$ cat file1**. 

the output will be 

I am Advin Suryavanshi.
I am a student.
I am pursuing my bachelor of technology in computer science.
**hello reader.**

#### 6) To display content in reverse order

The command is: 

**$ tac file1**

output:-

hello reader.

I am pursuing my bachelor of technology in computer science.

I am a student.

I am Advin Suryavanshi.

#### 7) To see the content of all text files in the folder. 

The command is: 

**$ cat *.txt**

output:-

It Will show the content of all text files present in the folder.

#### 8) Copy the contents from one file to another.

The command is: 

**$ cat [source file] > [destination file]**

output:-

content for the source file will get copied into the destination file.

example: **$ cat file1 > file2**

now,** file2 **will have the content of **file1.**

#### 9) To append one file's content to the end of another.

The command is: 

**$ cat file1 >> file2**

output:-

content of **file1** is appended at the end of **file2**.

#### 10) To suppress repeated empty lines

The command is: 

**$ cat -s file1**

output:-

In case your file has a lot of repeated empty lines. This command will reduce it to a single empty line.

#### 11) To merge multiple files into one 

The command is: 

**$ cat "file1" "fille2" "file3" > "final_file"**

output:-

The content of **file1**,** file2**, and** file3** will be inserted into the **final_file** in the given order.

#### 12) To highlight the end of every line. 

The command is: 

**$ cat -E "file1"**

output:-

end of every line will be highlighted.


There are some other uses of the cat command too. here I have mentioned the most common uses of the cat command.



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