comm – command is to to compare two sorted files line by line.
By default (without no options) it will produce 3 colums as output.
- Column 1 contains lines unique to file1.
- Column 2 contains lines unique to file2.
- Column 3 contains lines common to both files.
$ comm file1 file2
$ comm -1 file1 file2
$ comm -2 file1 file2
$ comm -3 file1 file2
In above examples
-1 is for surpass lines unique to file1.
-2 is for surpass lines unique to file2.
-3 is for surpass lines that appear in both files.