http://www.microsoft.com/technet/scriptcenter/csc/scripts/backup/backup/cscbk013.mspx

Backup Files Using Windows PowerShell

Submitted By: Greg Lyon

Language: Windows PowerShell

Description: Backs up files using Windows PowerShell.

Script Code

Backup Files Using Windows PowerShell

# BackupFiles.ps1
# Greg Lyon - July 2006

# -----------------------------------------------------

function BackupFolder
{
    param( [object] $objSrcFolder, [object] $objDstFolder)

    $strSrcFolder = $objSrcFolder.Path
    $strDstFolder = $objDstFolder.Path

    $colSrcFiles = $objSrcFolder.Files
    $colDstFiles = $objDstFolder.Files

    foreach ($objSrcFile in $colSrcFiles)
    {
        $strSrcFile = $strSrcFolder + "\" + $objSrcFile.Name
        $strDstFile = $strDstFolder + "\" + $objSrcFile.Name
        if($FSO.FileExists($strDstFile))
        {
            $objDstFile = $FSO.GetFile($strDstFile)
            $dtSrcFile = $objSrcFile.DateLastModified
            $dtDstFile = $objDstFile.DateLastModified
            $iSec = (New-TimeSpan -Start $dtDstFile -End $dtSrcFile).TotalSeconds
            if($iSec -gt 2) # allow 2 seconds difference for CD, network drive etc.
            {
                $FSO.CopyFile($strSrcFile, $strDstFile, $true)
                Write-Host "Copied file $strSrcFile to $strDstFile"
                $script:iCopyCount++
            }
        }
        else
        {
            $FSO.CopyFile($strSrcFile, $strDstFile, $true)
            Write-Host "Copied file $strSrcFile to $strDstFile"
            $script:iCopyCount++
        }
    }

    foreach($objDstFile In $colDstFiles)
    {
        $strDstFile = $objDstFile.Path
        $strSrcFile = $strSrcFolder + "\" + $objDstFile.Name

        if( -not $FSO.FileExists($strSrcFile))
        {
            $FSO.DeleteFile($strDstFile)
            Write-Host "Deleted file $strDstFile"
            $script:iDestDeletedCount++
        }
    }

    DoSubFolders $objSrcFolder $objDstFolder
}

# -----------------------------------------------------

function DoSubFolders
{
    param([object] $objSrcFolder, [object] $objDstFolder)

    $colSrcSubFolders = $objSrcFolder.SubFolders

    foreach($objSrcSubFolder in $colSrcSubFolders)
    {
        $strSrcSubFolder = $objSrcSubFolder.Path
        $strDstSubFolder = $strSrcSubFolder.Replace($strSourceFolder, $strDestinationFolder)
        if( -not $FSO.FolderExists($strDstSubFolder))
        {
            $FSO.CreateFolder($strDstSubFolder)
            Write-Host "Created folder $strDstSubFolder"
        }
        $objDstSubFolder = $FSO.GetFolder($strDstSubFolder)
        BackupFolder $objSrcSubFolder $objDstSubFolder
        DoSubFolders $objSrcSubFolder $objDstSubFolder
    }
}
# -----------------------------------------------------
function WaitKey
{
    param( [String] $strPrompt = "Press any key to continue ... ")
    Write-Host
    Write-Host $strPrompt -NoNewline
    $key = [Console]::ReadKey($true)
    Write-Host
}

# -----------------------------------------------------
# main

$strSourceFolder      = "D:\PS1"
$strDestinationFolder = "E:\Drive_D_Copy\PS1"

$iCopyCount = 0
$iDestDeletedCount = 0

Write-Host
Write-Host "Backing up " -NoNewline -ForegroundColor "White"
Write-Host $strSourceFolder -ForegroundColor "Cyan" -NoNewline
Write-Host " to " -NoNewline -ForegroundColor "White"
Write-Host $strDestinationFolder -ForegroundColor "Cyan"
Write-Host

$FSO = New-Object -COM Scripting.FileSystemObject

if( -not $FSO.FolderExists($strSourceFolder) )
{
    Write-Host "Error: source folder does not exist!" -ForegroundColor "Red"
    Write-Host
    Write-Host "Exiting script"
    WaitKey "Press any key to exit ... "
    exit
}

if( -not $FSO.FolderExists($strDestinationFolder) )
{
    Write-Host "Warning: destination folder does not exist"
    $p = Read-Host "Create folder and continue? "
    Write-Host
    if( $p.Substring(0, 1).ToUpper() -eq "Y" )
    {
        $FSO.CreateFolder($strDestinationFolder)
    }
    else
    {
        Write-Host "Exiting script"
        WaitKey "Press any key to exit ... "
        exit
    }
}

$objSourceFolder = $FSO.GetFolder($strSourceFolder)
$objDestinationFolder = $FSO.GetFolder($strDestinationFolder)

BackupFolder $objSourceFolder $objDestinationFolder

if( ($iCopyCount -eq 0) -and ($iDestDeletedCount -eq 0) )
{
    Write-Host
    Write-Host "Folders are synchronized" -ForegroundColor "magenta"
}
else
{
    Write-Host
    Write-Host $iCopyCount "files copied from source to destination" -ForegroundColor "magenta"
    Write-Host $iDestDeletedCount "orphaned destination files deleted" -ForegroundColor "magenta"
}

WaitKey "Press any key to exit ... "

# -----------------------------------------------------