How to copy certain files (w/o folder hierarchy), but do not overwrite existing files?

I would produce the list of files first and validate as you go through the list.

Something like this:

$srcdir = "\\server\source\";$destdir = "C:\destination\";$files = (Get-ChildItem $SrcDir -recurse -filter *.doc | where-object {-not ($_.PSIsContainer)});$files|foreach($_){    if (!([system.io.file]::Exists($destdir+$_.name))){                cp $_.Fullname ($destdir+$_.name)    };}

So, use Get-ChildItem to list files in source folder matching the filter, pipe through where-object to strip directories out.

Then go through each file in a foreach loop and check if the filename (not Fullname) exists in the destination using the Exists method of the system.io.file .NET class.

If it doesn't, copy, using only original filename (dropping original path).

Use the -whatif option on the copy when testing, so it only displays what it would do, in case result is not what you wanted :-)

The previous answers seem rather overcomplicated to me, unless I'm misunderstanding something. This should work:

Get-ChildItem "\\server\source\" *.doc -Recurse | ?{-not ($_.PSIsContainer -or (Test-Path "C:\Destination\$_"))} | Copy-Item -Destination "C:\Destination"

None of the built-in commands - copy, xcopy, or robocopy - will do what you want on their own, but there's a utility called xxcopy that will, conveniently available at http://www.xxcopy.com. It has a number of built-in options specifically for flattening directory trees into a single directory. The following will do what you described:

xxcopy "\\server\source\*.doc" "C:\Destination" /SGFO

However, xxcopy has various other options for handling duplicate filenames than just copying the first one encountered, such as adding the source directory name to the filename, or adding sequential numerical identifies to all but the first one, or all but the newest or oldest. See this page for details: http://www.xxcopy.com/xxcopy16.htm

# Get all *.doc files under \\server\sourceGet-ChildItem -Path \\server\source *.doc -Recurse |    # Filter out directores    Where-Object { -not $_.PsIsContainer } |     # Add property for destination    Add-Member ScriptProperty -Name Destination -Value { Join-Path 'C:\destination' $this.Name } -PassThru |    # Filter out files that exist on the destination    Where-Object { -not (Test-Path -Path $_.Destination -PathType Leaf } |     # Copy.     Copy-Item