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FOSS app eases the pain for San Diego community clinic
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comm(1) General Commands Manual 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 industry standards and associated tags. OPTIONS
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. OPERANDS
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 unde- fined. 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 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. EXIT STATUS
Successful completion. Error occurred. EXAMPLES
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 Dal- las Detroit Houston Kansas City Los Angeles Milwaukee Minneapolis Montreal New York Oakland Philadel- phia 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 SEE ALSO
Commands: cmp(1), diff(1), sdiff(1), sort(1), uniq(1) comm(1)
