Cat command in Linux with examples - GeeksforGeeks

06 Dec, 2021
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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