How to say no to all "do you want to overwrite" prompts in a batch file copy?

By default, copying from the command prompt will prompt you to overwrite files that already exist in the target location.

You can add "/Y" to say "Yes to all" replacements.

But how can you say "No to all" ?

In other words, I want to copy everything from one directory that does not already exist in the target.

The closest thing I see is the XCOPY argument to only copy things after a specific mod-datetime.

Unless there's a scenario where you'd not want to copy existing files in the source that have changed since the last copy, why not use XCOPY with /D without specifying a date?

echo "No" | copy/-Y c:\source c:\Dest\

You can make a text file with a single long line of "n" then run your command and put < nc.txt after it. I did this to copy over 145,000 instances where "No overwrite" was what I wanted and it worked fine this way.

Or you can just hold the n key down with something, but that takes longer than using the < to pipe it in.

Here's a workaround. If you want to copy everything from A that does not already exist in B:

Copy A to a new directory C. Copy B to C, overwriting anything that overlaps with A. Copy C to B.

I use XCOPY with the following parameters for copying .NET assemblies:

/D /Y /R /H 

/D:m-d-y - Copies files changed on or after the specified date. If no date is given, copies only those files whose source time is newer than the destination time.

/Y - Suppresses prompting to confirm you want to overwrite an existing destination file.

/R - Overwrites read-only files.

/H - Copies hidden and system files also.