comm

The comm command compares two sorted files, it gives 3 columnar output

• first column contains lines unique to the first file
• second column contains lines unique to the second file
• third column displays the common lines

syntax

comm [options]... File1 File2

Options	Function
-1	Does not display column 1 (does not display lines found only in file1).
-2	Does not display column 2 (does not display lines found only in file2).
-3	Does not display column 3 (does not display lines found in both files).
-i	Case insensitive comparison of lines.
--check-order	Check the order of the input, even if all input lines are pairable
--nocheck-order	Ignore the order of the input
--output-delimiter=STR	delimates columns with delimeter “STR”
--help	Displays a help menu
--version	Display command version information

Examples

• $ cat words.txt

Apple
Banana
Orange
India
US
Canada

• $ cat countries.txt

India
US
Canada

• $ comm -23 < (sort words.txt | uniq) < (sort countries.txt | uniq)

Apple 
Banana
Orange

• $ comm -12 < (sort words.txt | uniq) < (sort countries.txt | uniq)

India
US
Canada