Linux and Unix comm command

comm commandAbout comm
comm syntax
comm examples
Related commands
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About comm

Compare two sorted files line-by-line.


Compare sorted files FILE1 and FILE2 line-by-line.

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. Each of these columns can be suppressed individually with options.

comm syntax

comm [OPTION]... FILE1 FILE2



suppress column 1 (lines unique to FILE1)


suppress column 2 (lines unique to FILE2)


suppress column 3 (lines that appear in both files)


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


do not check that the input is correctly sorted


separate columns with string STR


display a help message, and exit.


output version information, and exit.

comm examples

comm -12 myfile1.txt myfile2.txt

Print only the lines present in both myfile1.txt and myfile2.txt.

comm -3 myfile1.txt myfile2.txt

Print only the lines that are present in myfile1.txt and not myfile2.txt, and vice versa.

cmp — Compare two files byte by byte.
diff — Identify the differences between two files.
join — Join the lines of two files which share a common field of data.
sort — Sort the lines in a text file.
uniq — Identify, and optionally filter out, repeated lines in a file.