Microsoft KB Archive/126457

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

Article ID: 126457

Article Last Modified on 5/6/2003

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APPLIES TO


 * Microsoft MS-DOS 3.1
 * Microsoft MS-DOS 3.2 Standard Edition
 * Microsoft MS-DOS 3.21 Standard Edition
 * Microsoft MS-DOS 3.3 Standard Edition
 * Microsoft MS-DOS 3.3a
 * Microsoft MS-DOS 4.0 Standard Edition
 * Microsoft MS-DOS 4.01 Standard Edition
 * Microsoft MS-DOS 5.0 Standard Edition
 * Microsoft MS-DOS 5.0a
 * Microsoft MS-DOS 6.0 Standard Edition
 * Microsoft MS-DOS 6.2 Standard Edition
 * Microsoft MS-DOS 6.21 Standard Edition
 * Microsoft MS-DOS 6.22 Standard Edition

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This article was previously published under Q126457



SUMMARY
Some versions of the MS-DOS "User's Guide" and online Help indicate that the /V (verify) switch for the COPY and XCOPY commands actually compares the source and destination files to determine whether they are identical. This is not correct. The /V switch verifies that the destination file, once written, can be read. No comparison of the files occurs.

This information also applies to the VERIFY ON command.



MORE INFORMATION
When you use the VERIFY ON command, or the /V switch with the COPY or XCOPY command, the MS-DOS file system uses the block device driver command code function 09H, Write with Verify. This verification process consists of confirming that the data just written can be read (for example, that the data was not written to a bad sector on the disk). No comparison of the source and destination data occurs.

To compare the source and destination files, use the MS-DOS FC (file compare) command after you use the COPY or XCOPY command.

