Powershell Copy-Item但仅复制更改的文件

Question

我试图通过目录递归并将其从A复制到B.可以通过以下方式完成:

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

我希望能够只复制新文件(存在于src但不存在于dest中的文件),并且只复制基于CRC校验而不是日期时间戳的可能已更改的文件.

$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() 

这段代码给了我一个特定文件的CRC校验...我只是不确定如何把两个脚本放在一起真正给我我需要的东西.我也不知道上面的CRC校验是否真的是这样做的正确方法.

有没有人有任何见解？

Answer 1

这两个都是PowerShell的可靠答案,但是利用Robocopy(MS提供的强大复制应用程序)可能要容易得多.

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

会完成同样的事情.

Answer 2

以下是一些指导如何使脚本更易于维护的指南.

将原始脚本Conver作为过滤器.

filter HasChanged { 
    param($file)

    # if $file's MD5 has does not exist
    # then return $_
}

然后只需过滤所有更新的文件并复制它们.

# Note that "Copy-Item" here does not preserve original directory structure
# Every updated file gets copied right under "C:\MyTest2"
ls C:\MyTest -Recurse | HasChanged | Copy-Item -Path {$_} C:\MyTest2

或者您可以创建另一个生成子目录的函数

ls C:\MyTest -Recurse | HasChanged | % { Copy-Item $_ GenerateSubDirectory(...) }

Answer 3

我找到了一个解决方案......但不确定从性能角度来看它是最好的：

$Source = "c:\scripts"
$Destination = "c:\test"
###################################################
###################################################
Param($Source,$Destination)
function Get-FileMD5 {
    Param([string]$file)
    $mode = [System.IO.FileMode]("open")
    $access = [System.IO.FileAccess]("Read")
    $md5 = New-Object System.Security.Cryptography.MD5CryptoServiceProvider
    $fs = New-Object System.IO.FileStream($file,$mode,$access)
    $Hash = $md5.ComputeHash($fs)
    $fs.Close()
    [string]$Hash = $Hash
    Return $Hash
}
function Copy-LatestFile{
    Param($File1,$File2,[switch]$whatif)
    $File1Date = get-Item $File1 | foreach-Object{$_.LastWriteTimeUTC}
    $File2Date = get-Item $File2 | foreach-Object{$_.LastWriteTimeUTC}
    if($File1Date -gt $File2Date)
    {
        Write-Host "$File1 is Newer... Copying..."
        if($whatif){Copy-Item -path $File1 -dest $File2 -force -whatif}
        else{Copy-Item -path $File1 -dest $File2 -force}
    }
    else
    {
        #Don't want to copy this in my case..but good to know
        #Write-Host "$File2 is Newer... Copying..."
        #if($whatif){Copy-Item -path $File2 -dest $File1 -force -whatif}
        #else{Copy-Item -path $File2 -dest $File1 -force}
    }
    Write-Host
}

# Getting Files/Folders from Source and Destination
$SrcEntries = Get-ChildItem $Source -Recurse
$DesEntries = Get-ChildItem $Destination -Recurse

# Parsing the folders and Files from Collections
$Srcfolders = $SrcEntries | Where-Object{$_.PSIsContainer}
$SrcFiles = $SrcEntries | Where-Object{!$_.PSIsContainer}
$Desfolders = $DesEntries | Where-Object{$_.PSIsContainer}
$DesFiles = $DesEntries | Where-Object{!$_.PSIsContainer}

# Checking for Folders that are in Source, but not in Destination
foreach($folder in $Srcfolders)
{
    $SrcFolderPath = $source -replace "\\","\\" -replace "\:","\:"
    $DesFolder = $folder.Fullname -replace $SrcFolderPath,$Destination
    if(!(test-path $DesFolder))
    {
        Write-Host "Folder $DesFolder Missing. Creating it!"
        new-Item $DesFolder -type Directory | out-Null
    }
}

# Checking for Folders that are in Destinatino, but not in Source
foreach($folder in $Desfolders)
{
    $DesFilePath = $Destination -replace "\\","\\" -replace "\:","\:"
    $SrcFolder = $folder.Fullname -replace $DesFilePath,$Source
    if(!(test-path $SrcFolder))
    {
        Write-Host "Folder $SrcFolder Missing. Creating it!"
        new-Item $SrcFolder -type Directory | out-Null
    }
}

# Checking for Files that are in the Source, but not in Destination
foreach($entry in $SrcFiles)
{
    $SrcFullname = $entry.fullname
    $SrcName = $entry.Name
    $SrcFilePath = $Source -replace "\\","\\" -replace "\:","\:"
    $DesFile = $SrcFullname -replace $SrcFilePath,$Destination
    if(test-Path $Desfile)
    {
        $SrcMD5 = Get-FileMD5 $SrcFullname
        $DesMD5 = Get-FileMD5 $DesFile
        If(Compare-Object $srcMD5 $desMD5)
        {
            Write-Host "The Files MD5's are Different... Checking Write
            Dates"
            Write-Host $SrcMD5
            Write-Host $DesMD5
            Copy-LatestFile $SrcFullname $DesFile
        }
    }
    else
    {
        Write-Host "$Desfile Missing... Copying from $SrcFullname"
        copy-Item -path $SrcFullName -dest $DesFile -force
    }
}

# Checking for Files that are in the Destinatino, but not in Source
foreach($entry in $DesFiles)
{
    $DesFullname = $entry.fullname
    $DesName = $entry.Name
    $DesFilePath = $Destination -replace "\\","\\" -replace "\:","\:"
    $SrcFile = $DesFullname -replace $DesFilePath,$Source
    if(!(test-Path $SrcFile))
    {
        Write-Host "$SrcFile Missing... Copying from $DesFullname"
        copy-Item -path $DesFullname -dest $SrcFile -force
    }
}