Question: I have many web applications in a Visual Studio solution.

All have the same post build command:

```
xcopy "$(TargetDir)*.dll" "D:\Project\bin" /i /d /y

```

It would be useful to avoid replacing newer files with old ones (e.g. someone could accidentally add a reference to an old version of a DLL).

How can I use xcopy to replace old files only with **newer DLL files** generated by Visual Studio?

Answer: 
User following command to copy all new and modified file from source to destination

xcopy c:\source d:\destination /D /I /E /Y

/D to check any modified file are there  

/I If the destination does not exist and copying more than one file, assumes that destination must be a directory.  

/E To copy directory and sub directories  

/Y to suppress any over write prompt.
Not tested, but I use a similar command script for these sorts of tasks.

```
set DIR_DEST=D:\Project\bin
pushd "$(TargetDir)"

::
:: Move Files matching pattern and delete them
::
for %%g in (*.dll) do (xcopy "%%g" "%DIR_DEST%" /D /Y & del "%%g")

::
:: Move Files matching pattern
::
:: for %%g in (*.dll) do (xcopy "%%g" "%DIR_DEST%" /D /Y )

popd

```