Powershell Copy-Item but only copy changed files

Question

I am trying to recurse through a directory and copy it from A to B. That can be done with the following:

Copy-Item C:\MyTest C:\MyTest2 –recurse

I want to be able though to only copy new files (ones that exist in src but not dest) and also only copy files that may have changed based off a CRC check and not a datetime stamp.

$file = "c:\scripts"
param
(
$file
)

$algo = [System.Security.Cryptography.HashAlgorithm]::Create("MD5")
$stream = New-Object System.IO.FileStream($file, [System.IO.FileMode]::Open)

$md5StringBuilder = New-Object System.Text.StringBuilder
$algo.ComputeHash($stream) | `
% { [void] $md5StringBuilder.Append($_.ToString("x2")) }
$md5StringBuilder.ToString()

$stream.Dispose() 

This code gives me a CRC check on a specific file...I am just not sure how to put the two scripts together to really give me what I need. I also don't know if the CRC check above is actually the correct way of doing this.

Does anyone have any insight?

Answer 1

Both of those are solid answers for powershell, but it would probably be far more easy to just leverage Robocopy (MS Supplied robust copy application).

robocopy "C:\SourceDir\" "C:\DestDir\" /MIR

would accomplish the same thing.