comm - Compares two sorted files.
comm [-123] file1 file2
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 industry standards and associated tags.
Suppresses output of the first column (lines in file1
only). Suppresses output of the second column (lines in
file2 only). Suppresses output of the third column (lines
common to file1 and file2).
The command comm -123 produces no output.
A pathname of the first file to be compared. If file1 is a
hyphen (-), the standard input is used. 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 special, block special or character special
file, the results are undefined.
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 rightmost 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.
Successful completion. Error occurred.
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. To display any one or two of the three output
columns, include the appropriate flags to suppress
the columns you do not want. For example,
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
Commands: cmp(1), diff(1), sdiff(1), sort(1), uniq(1)
comm(1)
[ Back ] | 