-1     suppress column 1 (lines unique to FILE1)

-2     suppress column 2 (lines unique to FILE2)

-3     suppress column 3 (lines that appear in both files)

--check-order
       check that the input is correctly sorted, even if all input lines are pairable

--nocheck-order
       do not check that the input is correctly sorted

--output-delimiter=STR
       separate columns with STR

--help display this help and exit

--version
       output version information and exit