comm

The comm command is a command-line tool used to compare two sorted text files, line by line. It outputs three columns: lines only in the first file, lines only in the second file, and lines present in both files.

Here's the basic syntax:

comm [OPTION]... FILE1 FILE2

• FILE1 and FILE2 are the two input text files to be compared.
• By default, comm assumes that input files are sorted in ASCII order. If not, the results might be incorrect, so it's crucial to sort the files before using comm.
• The following options are available to modify the behavior of comm:
  • -1: Suppress printing lines unique to the first file.
  • -2: Suppress printing lines unique to the second file.
  • -3: Suppress printing lines that appear in both files.
  • -i: Ignore case differences in comparisons.
  • -u: Output only unique lines (excluding common lines).
  • -z: Use a NULL character as the output field separator.

This tool is commonly used to identify similarities and differences between two files, especially when analyzing and comparing large datasets or documenting changes between different versions of files.