Powershell – How to diff two folders in Windows Powershell

diff()powershell

I'm trying to find differences in the content of two folder structures using Windows Powershell. I have used the following method to ensure that the file names are the same, but this method does not tell me if the contents of the files are the same:

$firstFolder = Get-ChildItem -Recurse folder1
$secondFolder = Get-ChildItem -Recurse folder2
Compare-Object -ReferenceObject $firstFolder -DifferenceObject $secondFolder

The technique described in this ServerFault question works for diffing a single file, but these folders contain hundreds of files at a variety of depths.

The solution does not necessarily need to tell me what specifically in the files is different – just that they are. I am not interested in differences in metadata such as date, which I already know to be different.

Best Answer

If you want to wrap the compare into a loop I would take the following approach:

$folder1 = "C:\Users\jscott"
$folder2 = "C:\Users\public"

# Get all files under $folder1, filter out directories
$firstFolder = Get-ChildItem -Recurse $folder1 | Where-Object { -not $_.PsIsContainer }

$firstFolder | ForEach-Object {

    # Check if the file, from $folder1, exists with the same path under $folder2
    If ( Test-Path ( $_.FullName.Replace($folder1, $folder2) ) ) {

        # Compare the contents of the two files...
        If ( Compare-Object (Get-Content $_.FullName) (Get-Content $_.FullName.Replace($folder1, $folder2) ) ) {

            # List the paths of the files containing diffs
            $_.FullName
            $_.FullName.Replace($folder1, $folder2)

        }
    }   
}

Note that this will ignore files which do not exist in both $folder1 and $folder2.

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