# comm

> Select or reject lines common to two files. Both files must be sorted.

- Produce three tab-separated columns: lines only in first file, lines only in second file and common lines.

`comm {{file1}} {{file2}}`

- Print only lines common to both files.

`comm -12 {{file1}} {{file2}}`

- Print only lines common to both files, read one file from stdin.

`cat {{file1}} | comm -12 - {{file2}}`

- Print lines only found in first file.

`comm -23 {{file1}} {{file2}}`

- Print lines only found in second file.

`comm -13 {{file1}} {{file2}}`