Cat command in Linux with examples

Cat(concatenate) command is very frequently used in Linux. It reads data from the file and gives their content as output. It helps us to create, view, concatenate files. So let us see some frequently used cat commands. 

1) To view a single file
Command:

$cat filename

Output 

It will show content of given filename

2) To view multiple files
Command:

$cat file1 file2

Output 

This will show the content of file1 and file2.

3) To view contents of a file preceding with line numbers.
Command:

$cat -n filename

Output 

It will show content with line number
example:-cat-n  geeks.txt
1)This is geeks
2)A unique array

4) Create a file 
Command:

$ cat > newfile

Output 

Will create a file named newfile

5) Copy the contents of one file to another file.
Command:

$cat [filename-whose-contents-is-to-be-copied] > [destination-filename]

Output 

The content will be copied in destination file

6) Cat command can suppress repeated empty lines in output
Command:

$cat -s geeks.txt

Output 

Will suppress repeated empty lines in output

7) Cat command can append the contents of one file to the end of another file.
Command:

$cat file1 >> file2

Output 

Will append the contents of one file to the end of another file

8) Cat command can display content in reverse order using tac command.
Command:

 $tac filename

Output 

Will display content in reverse order 

9) Cat command can highlight the end of line.
Command:

$cat -E "filename"

Output 

Will highlight the end of line

10) If you want to use the -v, -E and -T option together, then instead of writing -vET in the command, you can just use the -A command line option.
Command 

$cat -A  "filename"

11) Cat command to open dashed files.
Command:

$cat -- "-dashfile"

Output 

Will display the content of -dashfile

12) Cat command if the file has a lot of content and can’t fit in the terminal.
Command:

$cat "filename" | more

Output 

Will show that much content, which could fit in terminal and will ask to show more.

13) Cat command to merge the contents of multiple files.
Command:

$cat "filename1" "filename2" "filename3" > "merged_filename"

Output 

Will merge the contents of file in respective order and will insert that content in "merged_filename".

14) Cat command to display the content of all text files in the folder.
Command:

$cat *.txt

Output 

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

15) Cat command to write in an already existing file. 

Command :

$cat >> geeks.txt
The newly added text.

Output

Will append the text "The newly added text." to the end of the file.

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