powershell - Replace only old files with new files in destination directory

Question

Hello All,

I wish to replace only the old file with new file

I tried

Set-Location C:\contains_newfolder_contents\Old Folder
Get-ChildItem | ForEach-Object { 
  if ((Test-Path 'C:\contains_newfolder_contents\Sample Folder\$_' ) -and
    (.$_.LastWriteTime -gt C:\contains_newfolder_contents\Sample Folder\$_.LastWriteTime' )) {
      Copy-Item .\$_ -destination 'C:\contains_newfolder_contents\Sample Folder' 
  }
}

Kindly correct me!

Answer 1

you can do it too:

Get-ChildItem "C:\contains_newfolder_contents\Old Folder" -file | sort LastWriteTime -Descending | select -First 1 | Copy-Item -Destination 'C:\contains_newfolder_contents\Sample Folder'

Answer 2

Here's a one-line solution. I used different folder names to make the example easier to read.

Get-ChildItem C:\temp\destination|foreach-object {$sourceItem = (get-item "c:\temp\source\$($_.name)" -erroraction ignore); if ($sourceItem -and $sourceItem.LastWriteTime -gt $_.lastwritetime) {Copy-Item -path $sourceItem -dest $_.fullname -verbose}}

For each existing file, it finds the matching file in the source folder. $sourcItem will be null if there is no matching source item. It proceeds to compare the dates and copy if the source date is newer.

Answer 3

Instead of making several reads to the source, I propose you make a lookup table and then these simple commands will achieve the desired results.

$source       = 'C:\temp\Source'
$destintation = 'C:\temp\Destination'

$lookup = Get-ChildItem $destintation | Group-Object -Property name -AsHashTable

Get-ChildItem -Path $source |
    Where-Object {$_.lastwritetime -gt $lookup[$_.name].lastwritetime} |
        Copy-Item -Destination $destintation