Computer and Software Support

DOS Command Comp


COMP [d:][path][filename] [d:][path][filename] [/A][/C][/D][/L][/N:(number)]

Compares two groups of files to find information that does not match. (In DOS Version 6, this program is stored on the DOS supplemental disk.)


Compares two files or two groups of files. The files can have the same names, or different names. Wildcard characters (? and *) can be used to specify groups of files to be compared (files of the same names will be compared).

Each set of specified files will be compared, one set at a time.

Before starting the comparison, the program checks to see if files contain a valid end-of-file mark. COMP will not compare files that do not contain an end-of-file marker. If a specified file does not contain such a mark, the following error message will be displayed:

EOF mark not found

This mark is created by your word processor or other application program to indicate the end of the file. You can create the end- of-file marker by pressing and holding the Ctrl key and then pressing the letter Z key.

The COMP program also checks to make sure the file sizes indicated in the directory are the same for compared files; a comparison is not carried out if the files are stored as different sizes.

If you enter one or more pathnames or filenames after the command name, when you press the Enter key the comparison will begin immediately; therefore, you should make sure the diskette(s) containing the files to be compared are already in the specified drives. If you want to change diskettes after entering the command, enter the command name with no following parameters. If you enter the COMP command with no options , the program will prompt you for the file and/or path designations.

First, the program will display:

Enter primary filename

Enter the name of the first file or group of files. Next, the program will display:

Enter 2nd filename or drive ID

After you enter the second filename(s), the program will compare the files, issuing reports on its progress.

If the files are identical, it will report:

Files compare OK

If the files are not identical, it will report on the differences it finds.

COMP will display the memory locations of any portions of the compared files that do not match. After ten mismatches, the program terminates the comparison. The following message is displayed

10 Mismatches - ending compare

After all pairs specified have been compared, COMP will display

Compare more files (Y/N)?

To enter more files to compare, press the letter Y key. To terminate the comparisons, press the letter N key.


A - Displays the differences found between compared files as characters.

/C - Performs a comparison that is not case-sensitive.

/D - Displays the differences found between compared files in decimal format. (The default format is hexadecimal.)

/L - Displays the number of the line where the difference occurred, rather than the byte offset.

/N:(number) - Allows you to enter the number of lines in both files that will be compared, even if the files are of different sizes.


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