替代连接路径来处理不存在的驱动器

Question

I made a function that creates a file name.

The function breaks when sent a drive letter that doesn't exist.

I have have changed the function to not use join-path but I am wondering if there is another way?

The try / catch is not working as expected.

Perhaps the best answer is not using join-path ?

$fullPath = join-path -path $DirectoryName  -childpath ((Get-Date).ToString('yyyy_MM_ddThhmmss-') + ($ReportName + $Extension)) -ErrorAction SilentlyContinue

Answer 1

To emulate Join-Path 's behavior without the - surprising and vexing - requirement that a drive spec. (eg, N: ) refer to an existing drive (even though no other components are required to exist):

Pragmatically speaking, you can simply use string concatenation / interpolation to join your path components:

$dir = 'N:\foo'; $file = 'bar'

# String concatenation
$joinedPath = $dir + '\' + $file

# String interpolation
$joinedPath = "$dir\$file"

# With an open-ended number of path components.
$components = $dir, 'sub', $file
$joinedPath = $components -join '\'

While, depending on the input components, this can result in accidentally duplicated path separators (eg, N:\\foo\\\\bar ), this is usually not a problem, because the file-system APIs treat such duplicates as a single separator; that is, N:\\foo\\\\bar is treated the same as N:\\foo\\bar .

If you want to avoid duplicated separators, see the solution in the next section.

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To more fully emulate Join-Path , which involves removing accidentally duplicated separators and normalizing them to the platform-native form (eg, on Windows, / -> \\ ), use the following:

$dir = 'N:\foo'; $file = 'bar.txt'
$components = $dir, $file

$joinedPath = 
  ($components -join '\') -replace '(?!^)([\\/])+', [IO.Path]::DirectorySeparatorChar

To wrap this up in a (very simple) function, join-AnyPath :

function join-AnyPath {
  ($args -join '\') -replace '(?!^)([\\/])+', [IO.Path]::DirectorySeparatorChar
}

# Sample call
join-AnyPath N:\dir\ /foo/ bar.txt

The above yields N:\\dir\\foo\\bar.txt (on Windows).

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Note: Theo points out that there's also the [IO.Path]::Combine() .NET method, but while it doesn't require that a drive exist either, its behavior differs from Join-Path with respect to how \\ -prefixed components are handled, which can lead to surprising results: see this answer .