comm Command in Linux with Examples

DESCRIPTION

Compares two files and tells you what line numbers are different.

SYNOPSIS

comm [OPTION]… FILE1 FILE2

OPTIONS :

-1
Suppress the output column of lines unique to file1.
-2
Suppress the output column of lines unique to file2.
-3
Suppress the output column of lines duplicated in file1 and file2.
file1
Name of the first file to compare.
file2
Name of the second file to compare.

EXAMPLES

Two provide examples for this command, lets consider two files :

$ cat file1.txt
abc
def
ghi
$ cat file2.txt
abc
ghi
klm

In the below examples,

First column displays the lines unique in file1
Second column displays the lines unique in file2
Third column displays the lines that are common in both the files.

1. Simple Command Usage

$ comm file1.txt file2.txt
		abc
def
		ghi
	klm

2. Suppress first column

$ comm -1 file1.txt file2.txt
	abc
	ghi
klm

3. Suppress second column

$ comm -2 file1.txt file2.txt
	abc
def
	ghi

3. Suppress third column

$ comm -3 file1.txt file2.txt
def
	klm