作为Kory Gill cmets，我也不明白您为什么要更改文件的扩展名。
如果目标文件应该已经存在，我的想法是在文件的基本名称上添加一个序列号。
事实上，如果您手动尝试复制/粘贴已存在的文件，Windows 也建议在文件中添加序列号。
为此，此功能可能很有用：
function Copy-Unique {
# Copies files to a destination. If a file with the same name already exists in the destination,
# the function will create a unique filename by appending '(x)' after the name, but before the extension.
# The 'x' is a numeric sequence value.
[CmdletBinding()]
Param(
[Parameter(Mandatory = $true, ValueFromPipeline = $true, Position = 0)]
[Alias("Path")]
[ValidateScript({Test-Path -Path $_ -PathType Container})]
[string]$SourceFolder,
[Parameter(Mandatory = $true, Position = 1)]
[string]$DestinationFolder,
[Parameter(Mandatory = $false, Position = 2)]
[string]$Filter = '*',
[switch]$Recurse
)
# create the destination path if it does not exist
if (!(Test-Path -Path $DestinationFolder -PathType Container)) {
Write-Verbose "Creating folder '$DestinationFolder'"
New-Item -Path $DestinationFolder -ItemType 'Directory' -Force | Out-Null
}
# get a list of file FullNames in this source folder
$sourceFiles = @(Get-ChildItem -Path $SourceFolder -Filter $Filter -File | Select-Object -ExpandProperty FullName)
foreach ($file in $sourceFiles) {
# split each filename into a basename and an extension variable
$baseName = [System.IO.Path]::GetFileNameWithoutExtension($file)
$extension = [System.IO.Path]::GetExtension($file) # this includes the dot
# get an array of all filenames (names only) of the files with a similar name already present in the destination folder
$allFiles = @(Get-ChildItem $DestinationFolder -File -Filter "$baseName*$extension" | Select-Object -ExpandProperty Name)
# for PowerShell version < 3.0 use this
# $allFiles = @(Get-ChildItem $DestinationFolder -Filter "$baseName*$extension" | Where-Object { !($_.PSIsContainer) } | Select-Object -ExpandProperty Name)
# construct the new filename
$newName = $baseName + $extension
$count = 1
while ($allFiles -contains $newName) {
$newName = "{0}({1}){2}" -f $baseName, $count, $extension
$count++
}
# use Join-Path to create a FullName for the file
$newFile = Join-Path -Path $DestinationFolder -ChildPath $newName
Write-Verbose "Copying '$file' as '$newFile'"
Copy-Item -Path $file -Destination $newFile -Force
}
if ($Recurse) {
# loop though each subfolder and call this function again
Get-ChildItem -Path $SourceFolder -Directory | Select-Object -ExpandProperty Name | ForEach-Object {
$newSource = (Join-Path -Path $SourceFolder -ChildPath $_)
$newDestination = (Join-Path -Path $DestinationFolder -ChildPath $_)
Copy-Unique -SourceFolder $newSource -DestinationFolder $newDestination -Filter $Filter -Recurse
}
}
}
我还建议对您的 Copy-1 函数进行一些更改，以使用上述 Copy-Unique 函数：
function Copy-1 {
[CmdletBinding()]
Param(
[Parameter(Mandatory = $true, Position = 0)]
[Alias("Path")]
[ValidateScript({Test-Path -Path $_ -PathType Container})]
[string]$Source,
[Parameter(Mandatory = $true, Position = 1)]
[string]$Destination,
[Parameter(Mandatory = $true, Position = 2)]
[int]$Threshold,
[string]$Filter = '*'
)
# you are not showing this function, so I have to assume it does what it needs to do
$remainingSpace = Get-FreeSpace
if($remainingSpace -gt $Threshold) {
Copy-Unique -SourceFolder $Source -DestinationFolder $Destination -Filter $Filter -Recurse -Verbose
}
else {
$answer = Read-Host -Prompt "Remaining space is now $remainingSpace. Press 'Q' to quit."
if ($answer -ne 'Q') {
# you have cleared space, and want to redo the copy action
Copy-1 -Source $Source -Destination $Destination -Filter $Filter
}
}
}
然后像这样使用它：
Copy-1 -Source 'source\path' -Destination 'destination\path' -Threshold 100 -Filter '*.extension'
Copy-1 -Source 'source\path' -Destination 'some\other\destination\path' -Threshold 100 -Filter '*.another_extension'
注意
当然，使用相同的参数一遍又一遍地运行它，最终会得到很多副本，因为该函数不会比较文件是否相等。如果您想进行真正的文件夹同步，我建议您使用专用软件或使用 RoboCopy。
使用 RoboCopy 进行目录同步的示例在 Internet 上几乎随处可见，例如 here