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Comp (command)

Command

Wikipedia contributorsAdapted for Fathomly · View authors
1 min read
Source updated June 2, 2026
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In computing, comp is a command used on DEC OS/8, DOS, DR FlexOS, IBM OS/2, Microsoft Windows and related computer operating systems such as ReactOS. It is used to perform comparisons of multiple computer files to show the differences between them.

01History

In DOS, the comp command first appeared in PC DOS 1.0 and has been included in most versions of MS-DOS and PC DOS. A newer command, fc was added in DOS 3.3 which allows for line comparisons in addition to binary comparisons. DR DOS 6.0 also includes an implementation of the comp command.

The FreeDOS version was developed by Paul Vojta and is licensed under the MIT License. Ged Murphy developed the ReactOS version. It is licensed under the GNU GPL 2.

The command is also available in the EFI shell.

COMP.COM (among other commands) in IBM PC DOS 1.0.
COMP.COM (among other commands) in IBM PC DOS 1.0.

02Syntax

The command-syntax is:

comp [<Data1>] [<Data2>] [/d] [/a] [/l] [/n=<Number>] [/c]

Parameters

  • <Data1>, Location and name of the first file or set of files
  • <Data2>, Location and name of the second file or set of files
  • /d, Display differences in decimal format (Default is hexadecimal)
  • /a, Display differences as characters
  • /l, Display the number of the line, instead of the byte offset
  • /n=<Number>, Compare only the specified number of lines for each file
  • /c, Perform a non case-sensitive comparison
  • /off[line], Process files with the offline attribute set
  • /?, Display Help
Watch videos about Comp (command)Explainers and documentaries on YouTube (opens in a new tab)

Sources and credits

This article is adapted from the Wikipedia article “Comp (command)”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

Images, from Wikimedia Commons:

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Related topics

File comparison

In computing, file comparison is the calculation and display of the differences and similarities between data objects, typically text files such as source code. The methods, implementations, and results are typically called a diff, after the Unix diff utility.

List of DOS commands

This article lists notable commands provided by the MS-DOS disk operating system, especially as used on an IBM PC compatible computer. Other DOS variants as well as the legacy Windows shell, Command Prompt (cmd.exe), provide many of these commands.

Diff

diff is a shell command that compares the content of files and reports differences. The term diff is also used to identify the output of the command and is used as a verb for running the command.