find lines that matches on 2 different sorted file

Supposed we have 2 sorted files:

file1

1
2
3
4
5

file2

3
4
5
6
7

comm is a utility for finding lines that appear (or not) between 2 files. The normal output are 3 column.

1. Lines that is unique on file 1

2. Lines that is unique on file 2

3. Lines that are appear on both

Examples

$ comm  file1 file2
1
2
		3
		4
		5
	6
	7

Find lines that on both file only

$ comm -12 file1 file2
3
4
5

-12 supresses (do not include) colunm 1 & 2

Fine line that is unique on first file

$ comm -23 file1 file2
1
2

For file that is not uniq or sorted

If file is not sorted, you can use the <(..) operator

$ comm <(sort -u file1) <(sort -u file2)
1
2
		3
		4
		5
	6
	7