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comm(1)								      comm(1)



NAME

  comm - Compares two sorted files.

SYNOPSIS

  comm [-123] file1 file2

STANDARDS

  Interfaces documented	on this	reference page conform to industry standards
  as follows:

  command: XCU5.0

  Refer	to the standards(5) reference page for more information	about indus-
  try standards	and associated tags.

OPTIONS

  -1  Suppresses output	of the first column (lines in file1 only).

  -2  Suppresses output	of the second column (lines in file2 only).

  -3  Suppresses output	of the third column (lines common to file1 and
      file2).

  The command comm -123	produces no output.

OPERANDS

  file1	  A pathname of	the first file to be compared. If file1	is a hyphen
	  (-), the standard input is used.

  file2	  A pathname of	the second file	to be compared.	If file2 is a hyphen
	  (-), the standard input is used.

  If both file1	and file2 refer	to standard input or to	the same FIFO spe-
  cial,	block special or character special file, the results are undefined.

DESCRIPTION

  The comm command reads file1 and file2 and writes three columns to standard
  output, showing which	lines are common to the	files and which	are unique to
  each.

  The leftmost column of standard output includes lines	that are in file1
  only.	 The middle column includes lines that are in file2 only.  The right-
  most column includes lines that are in both file1 and	file2.

  If you specify a hyphen (-) in place of one of the file names, comm reads
  standard input.

  Generally, file1 and file2 should be sorted according	to the collating
  sequence specified by	the LC_COLLATE environment variable. (See sort(1).)
  If the input files are not sorted properly, the output of comm might not be
  useful.



EXIT STATUS

  0   Successful completion.

  >>0  Error occurred.

EXAMPLES

   1.  In the following	examples, file1	contains the following sorted list of
       North American cities:


	    Anaheim
	    Baltimore
	    Boston
	    Chicago
	    Cleveland
	    Dallas
	    Detroit
	    Kansas City
	    Milwaukee
	    Minneapolis
	    New	York
	    Oakland
	    Seattle
	    Toronto

       The second file,	file2, contains	this sorted list:


	    Atlanta
	    Chicago
	    Cincinnati
	    Houston
	    Los	Angeles
	    Montreal
	    New	York
	    Philadelphia
	    Pittsburgh
	    San	Diego
	    San	Francisco
	    St.	Louis

       To display the lines unique to each file	and common to the two files,
       enter:
	    comm file1 file2

       This command results in the following output:
	    Anaheim
		    Atlanta
	    Baltimore
	    Boston
			    Chicago
		    Cincinnati
	    Cleveland
	    Dallas
	    Detroit
		    Houston
	    Kansas City
		    Los	Angeles
	    Milwaukee
	    Minneapolis
		    Montreal
			    New	York
	    Oakland
		    Philadelphia
		    Pittsburgh
		    San	Diego
		    San	Francisco
	    Seattle
		    St.	Louis
	    Toronto

       The leftmost column contains lines in file1 only, the middle column
       contains	lines in file2 only, and the rightmost column contains lines
       common to both files.

   2.  To display any one or two of the	three output columns, include the
       appropriate flags to suppress the columns you do	not want.  For exam-
       ple, the	following command displays columns 1 and 2 only:
	    comm -3 file1 file2

	    Anaheim
		   Atlanta
	    Baltimore
	    Boston
		   Cincinnati
	    Cleveland
	    Dallas
	    Detroit
		   Houston
	    Kansas City
		   Los Angeles
	    Milwaukee
	    Minneapolis
		   Montreal
	    Oakland
		   Philadelphia
		   Pittsburgh
		   San Diego
		   San Francisco
	    Seattle
		   St. Louis
	    Toronto

       The following command displays output from only the second column:
	    comm -13 file1 file2

	    Atlanta
	    Cincinnati
	    Houston
	    Los	Angeles
	    Montreal
	    Philadelphia
	    Pittsburgh
	    San	Diego
	    San	Francisco
	    St.	Louis

       The following command displays output from only the third column:
	    comm -12 file1 file2

	    Chicago
	    New	York








SEE ALSO

  Commands:  cmp(1), diff(1), sdiff(1),	sort(1), uniq(1)