Compare directories and sub directories and replace files based on MD5 hash

问题

Have a comparison script that compares based on MD5 hash. Noticed that it's doing odd things.

 $Source=  "D:\Folder1"
$Destination = "D:\folder2"

get-childitem $Source -Recurse | foreach {
 #Calculate hash using Algorithm MD5 reference http://www.tomsitpro.com/articles/powershell-file-hash-check,2-880.html
 Write-Host "Copying $($_.fullname) to $Destination" -ForegroundColor Yellow
 $OriginalHash = Get-FileHash -Path $_.FullName -Algorithm MD5

 #Now copy what's different
 $replacedfile = $_ | Copy-Item -Destination $Destination -Force -PassThru

 #Check the hash sum of the file copied
 $copyHash = Get-FileHash -Path $replacedfile.FullName -Algorithm MD5

 #compare them up
 if ($OriginalHash.hash -ne $copyHash.hash) {
    Write-Warning "$($_.Fullname) and $($replacedfile.fullname) Files don't match!" 
 }
 else {
    Write-Host "$($_.Fullname) and $($replacedfile.fullname) Files Match" -ForegroundColor Green
 }
} #Win!

The script works fine, until it finds a difference in a sub folder. It then for some reason i can't seem to find, it copies the different item to BOTH the top level and the sub level.....I am being really dumb and I can't see the issue, need a second pair of eyes.

Example

File Test.Txt is in Source\SubFolder

Script runs and puts Test.Txt in Destination\Subfolder AND Destination.....

Any ideas?

回答1:

The line $replacedfile = $_ | is a fault, here $_ contains only the name without the subdir, and is copied to $Destination.

Replace the line:

$replacedfile = $_ | Copy-Item -Destination $Destination -Force -PassThru

with:

$replacedfile = $_.Fullname -replace [RegEx]::escape($Source),$Destination

This replaces the differing base part leaving the curent source sub dir intact. The [RegEx]::escape($Source) is necessary because the source string contains
backslashes which would be interpreted as an escape char by the replace function.

EDIT Complete script to avoid ambiguities:

$Source=  "D:\Folder1"
$Destination = "D:\folder2"

get-childitem $Source -Recurse | foreach {
    #Calculate hash using Algorithm MD5 reference http://www.tomsitpro.com/articles/powershell-file-hash-check,2-880.html
    $SrcFile = $_.FullName
    $SrcHash = Get-FileHash -Path $SrcFile -Algorithm MD5

    $DestFile = $_.Fullname -replace [RegEx]::escape($Source),$Destination
    Write-Host "Copying $SrcFile to $DestFile" -ForegroundColor Yellow

    if (Test-Path $DestFile) {
        #Check the hash sum of the file copied
        $DestHash = Get-FileHash -Path $DestFile -Algorithm MD5

        #compare them up
        if ($SrcHash.hash -ne $DestHash.hash) {
            Write-Warning "$SrcFile and $DestFile Files don't match!" 
            Copy-Item $SrcFile -Destination $DestFile -Force
        } else {
            Write-Host "$SrcFile and $DestFile Files Match" -ForegroundColor Green
        }
    } else {
        Copy-Item $SrcFile -Destination $DestFile -Force
    }
}

来源：https://stackoverflow.com/questions/41876703/compare-directories-and-sub-directories-and-replace-files-based-on-md5-hash

标签

powershell

md5