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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