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

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

<p>But how can you say "No to all" ?</p>

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

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

I expect
xxcopy
has an
option
for that.
Bingo:
http://www.xxcopy.com/xxcopy27.htm#tag_231
```
```
2.3   By comparison with the file in destination

    The switches in this group select files based on the
    comparison between the files in the source and those in
    the destination.  They are often used for periodic backup
    and directory synchronization purposes. These switches
    were originally created as variations of directory backup.
    They are also convenient for selecting files for deletion.

2.3.1  by Presence/Absence

    The /BB and /U switches are the two switches which select
    files by the pure presence or absence as the criteria.
    Other switches in the this group (Group 2.3) are also
    affected by the file in the destination, but for a
    particular characteristics for comparison's sake.

    /BB  Selects files that are present in source but not in destination.
    /U   Selects files that are present in both source and destination.
```
```
-Adam