Copying all Files in Subdirectories to a Single Folder with Robocopy Updating Capabilities

Question

I am trying to copy all the files in a directory that contains many subfolders into a single separate folder. When the code is run again, rather than replacing each file in the destination folder, it should skip files that have the same timestamp and only replace those that are older.

I have used robocopy to skip the copying of files that are of the current version/older in the destination folder. However, robocopy only copies the entire directory along with its folder structure so I am unable to obtain the desired folder with a list of all the files from the source.

I have also used get child-item and then copy-item. However, although this is able to get rid of the folder structure, it overwrites each file for each iteration and is thus time-consuming.

So what I want is to combine the capabilities of robocopy and copy-item. Note that there are no specific pattern to the files that I am to copy. It is simply to COPY each file in the subdirectories that are EITHER of a NEWER version or NON-existing into a single folder.

#For copying and ease of updating destination folder
robocopy /purge /np /S /xo 'source' 'destination'

#To copy items into the destination folder without keeping folder structure
Get-ChildItem -Path 'source' -Recurse -File | Copy-Item -Destination 'destination'

Was unable to combine both, So I am stuck with using the 'copy-item' code, which is quite time consuming when copying/updating large amounts of files.

Answer 1

The purpose of robocopy is to preserve the folder structure. If you want to mangle subfolders robocopy is not the right tool. Use the Get-ChildItem approach, group the results by file name, sort each group by date, pick the most recent file from each group, and copy it if the corresponding destination file either doesn't exist or is older.

Something like this should do what you want:

Get-ChildItem -Path 'C:\source' -Recurse -File |
    Group-Object Name |
    ForEach-Object {
        $src = $_.Group | Sort-Object | Select-Object -Last 1
        $dst = Join-Path 'C:\destination' $src.Name
        if (-not (Test-Path $dst) -or ($src.LastWriteTime -gt (Get-Item $dst).LastWriteTime)) {
            $src | Copy-Item -Destination $dst
        }
    }