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VERIFY ON, COPY /V, XCOPY /V Commands Do Not Compare Data

This article was previously published under Q126457
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This article was written about products for which Microsoft no longer offers support. Therefore, this article is offered "as is" and will no longer be updated.
Some versions of the MS-DOS "User's Guide" and online Help indicate thatthe /V (verify) switch for the COPY and XCOPY commands actually comparesthe source and destination files to determine whether they are identical.This is not correct. The /V switch verifies that the destination file, oncewritten, can be read. No comparison of the files occurs.

This information also applies to the VERIFY ON command.
When you use the VERIFY ON command, or the /V switch with the COPY or XCOPYcommand, the MS-DOS file system uses the block device driver command codefunction 09H, Write with Verify. This verification process consists ofconfirming that the data just written can be read (for example, that thedata was not written to a bad sector on the disk). No comparison of thesource and destination data occurs.

To compare the source and destination files, use the MS-DOS FC (filecompare) command after you use the COPY or XCOPY command.
For more information about the VERIFY, COPY, XCOPY, or FC command, see yourMS-DOS "User's Guide," or use the online Help in MS-DOS versions 5.0 andlater.

"Advanced MS-DOS Programming," Ray Duncan, Microsoft Press, Chapter 14,pages 267-276
3.x 4.x 5.x 6.00 6.20 6.21 6.22

Article ID: 126457 - Last Review: 05/06/2003 20:00:54 - Revision: 2.0

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