The command is not included in Windows 11. xcopy is a like command
Example
Copy the complete contents of the diskette in Drive A drive to the diskette in B drive.
>diskcopy a: b:
If there is only have one diskette drive, diskcopy can be done by typing the source drive only. The disk copy program will prompt to insert the second (target) diskette once it finishes reading the complete contents of the first (source) diskette track by track into memory.
>diskcopy a:
If only the first side of the diskette needs to be copied, even if the target diskette is double sided, the /1 switch can be used.
>diskcopy a: /1
To make sure the contents are written reliably, the /V switch can be used, but it will cost more time to copy.
>diskcopy a: /V
Force diskcopy to use only the conventional memory for temporary storage:
>diskcopy a: /M
Limitation
Diskcopy does not work with hard disk drives, CDs, network drives, Zip drives, or USB drives, etc. It also does not allow diskcopy from 3.5 inch drive to 5.25 inch drives, and vice versa. The source and target drive must be the same size.[20]
^Shustek, Len (2014-03-24). "Microsoft MS-DOS early source code". Software Gems: The Computer History Museum Historical Source Code Series. Retrieved 2015-10-01.
^Wolverton, Van (2003). Running MS-DOS Version 6.22 (20th Anniversary Edition), 6th Revised edition. Microsoft Press. ISBN0-7356-1812-7.