How do I get a path with the correct (canonical) case in PowerShell?

Question

I have a script that accepts a directory as an argument from the user. I'd like to display the name of the directory path as it is displayed in Windows. I.e.,

PS C:\SomeDirectory> cd .\anotherdirectory
PS C:\AnotherDirectory> . .\myscript.ps1 "c:\somedirectory"
C:\SomeDirectory

How do I retrieve "C:\SomeDirectory" when given "c:\somedirectory"?

Answer 1

The accepted answer only gets the correct case of the file. Parent paths are left with the case provided by the user. Here's my solution.

$getPathNameSignature = @'
[DllImport("kernel32.dll", SetLastError=true, CharSet=CharSet.Auto)]
public static extern uint GetLongPathName(
    string shortPath, 
    StringBuilder sb, 
    int bufferSize);

[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError=true)]
public static extern uint GetShortPathName(
   string longPath,
   StringBuilder shortPath,
   uint bufferSize);
'@
$getPathNameType = Add-Type -MemberDefinition $getPathNameSignature -Name GetPathNameType -UsingNamespace System.Text -PassThru


function Get-PathCanonicalCase
{
    [CmdletBinding()]
    param(
        [Parameter(Mandatory=$true)]
        [string]
        # Gets the real case of a path
        $Path
    )

    if( -not (Test-Path $Path) )
    {
        Write-Error "Path '$Path' doesn't exist."
        return
    }

    $shortBuffer = New-Object Text.StringBuilder ($Path.Length * 2)
    [void] $getPathNameType::GetShortPathName( $Path, $shortBuffer, $shortBuffer.Capacity )

    $longBuffer = New-Object Text.StringBuilder ($Path.Length * 2)
    [void] $getPathNameType::GetLongPathName( $shortBuffer.ToString(), $longBuffer, $longBuffer.Capacity )

    return $longBuffer.ToString()
}

I've integrated the above code into Resolve-PathCase, part of the Carbon PowerShell module. Disclaimer: I'm the owner/maintainer of Carbon.

Answer 2

This should work:

function Get-PathCanonicalCase {
    param($path)

    $newPath = (Resolve-Path $path).Path
    $parent = Split-Path $newPath

    if($parent) {
        $leaf = Split-Path $newPath -Leaf

        (Get-ChildItem $parent| Where-Object{$_.Name -eq $leaf}).FullName
    } else {
        (Get-PSDrive ($newPath -split ':')[0]).Root
    }
}

Answer 3

I found a different and simpler approach using PowerShell wild cards.

 $canonicalCasePath = Get-ChildItem -Path $wrongCasingPath.Replace("\","\*") | Where FullName -IEQ $wrongCasingPath | Select -ExpandProperty FullName

• The first part of the pipe replaces all backslashes in the path by backslash and asterisk \ → \* and return all matching files
• The where part makes sure that only the desired file is returned and not any other potential match. IEQ is case insesitive equal
• The last select part extracts canonical case path of the file