comm

Compare two sorted files line by line and write to standard output:
the lines that are common, plus the lines that are unique.

SYNTAX
      comm [OPTION]... FILE1 FILE2

   a file name of `-' means standard input. 

   Before `comm' can be used, the input files must be sorted using the
collating sequence specified by the `LC_COLLATE' locale, with trailing
newlines significant.  If an input file ends in a non-newline
character, a newline is silently appended.  The `sort' command with no
options always outputs a file that is suitable input to `comm'.

   With no options, `comm' produces three column output.  Column one
contains lines unique to FILE1, column two contains lines unique to
FILE2, and column three contains lines common to both files.  Columns
are separated by a single TAB character.

   The options `-1', `-2', and `-3' suppress printing of the
corresponding columns.

   Unlike some other comparison utilities, `comm' has an exit status
that does not depend on the result of the comparison.  Upon normal
completion `comm' produces an exit code of zero.  If there is an error
it exits with nonzero status. 

Related commands:

cmp - Compare two files
diff - Display the differences between two files
diff3 - Show differences among three files
sdiff - merge two files interactively

Windows equivalent commands:

COMP - Compare two files and display any characters which do NOT match
FC Compare two files