C:\test\junk>dir /w a b
 Volume in drive C has no label.
 Volume Serial Number is BCCA-B4CC

 Directory of C:\test\junk\a

[.]  [..]
               0 File(s)              0 bytes

 Directory of C:\test\junk\b

[.]  [..]
               0 File(s)              0 bytes
               2 Dir(s)  15,859,965,952 bytes free

##</code><code>##

C:\test\junk>type makefile
all:
    xcopy /f /r /i /e /d a\*.* b\*.*

##</code><code>##

C:\test\junk>nmake all

Microsoft (R) Program Maintenance Utility Version 7.00.9466
Copyright (C) Microsoft Corporation.  All rights reserved.

        xcopy /f /r /i /e /d a\*.* b\*.*
0 File(s) copied

##</code><code>##

C:\test\junk>nmake all

Microsoft (R) Program Maintenance Utility Version 7.00.9466
Copyright (C) Microsoft Corporation.  All rights reserved.

        xcopy /f /r /i /e /d /b a\*.* b\*.*
Invalid switch - /b
NMAKE : fatal error U1077: 'xcopy' : return code '0x4'
Stop.