How do I deal with Paths when writing a PowerShell Cmdlet?

Question

What is the proper way to receive a file as a parameter when writing a C# cmdlet? So far I just have a property LiteralPath (aligning with their parameter naming convention) th

Answer 1

This is how you can handle Path input in a PowerShell script cmdlet:

function My-Cmdlet {
    [CmdletBinding(SupportsShouldProcess, ConfirmImpact='Medium')]
    Param(
        # The path to the location of a file. You can also pipe a path to My-Cmdlet.
        [Parameter(Mandatory, ValueFromPipeline, ValueFromPipelineByPropertyName)]
        [string[]] $Path
    )

    Begin {
        ...
    }

    Process {
        # ignore empty values
        # resolve the path
        # Convert it to remove provider path
        foreach($curPath in ($Path | Where-Object {$_} | Resolve-Path | Convert-Path)) {
            # test wether the input is a file
            if(Test-Path $curPath -PathType Leaf) {
                # now we have a valid path

                # confirm
                if ($PsCmdLet.ShouldProcess($curPath)) {
                    # for example
                    Write-Host $curPath
                }
            }
        }
    }

    End {
        ...
    }
}

You can invoke this method in the following ways:

With a direct path:

My-Cmdlet .

With a wildcard string:

My-Cmdlet *.txt

With an actual file:

My-Cmdlet .\PowerShell_transcript.20130714003415.txt

With a set of files in a variable:

$x = Get-ChildItem *.txt
My-Cmdlet -Path $x

Or with the name only:

My-Cmdlet -Path $x.Name

Or by pasing the set of files via the pipeline:

$x | My-Cmdlet