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I've been trying to wrap my brain around this behaviour for a while.

I have a PowerShell script within a module that's supposed to map a drive, then open it in file explorer.

The mapping part works, but it falls over when trying to open the drive with the error:

ii : Cannot find drive. A drive with the name 'L' does not exist.
At line:41 char:9
+         ii "$($global:mapping_letter):"
+         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (L:String) [Invoke-Item], DriveNotFoundException
    + FullyQualifiedErrorId : DriveNotFound,Microsoft.PowerShell.Commands.InvokeItemCommand

Strangely, running the final command ii "$($global:mapping_letter):" directly after running the script seems to work without issue. I thought that the net use command might be async and tried using Start-Sleep before the ii command, but this prevents the drive from even mapping until it's woken up again.

Code as below:

function MapDrive {
    Param(
        [Parameter(Mandatory=$true,Position=0)]
        [string] $DrivePath,
        [Parameter(Mandatory=$false,Position=1)]
        [int] $notadmin,
        [Parameter(Mandatory=$false,Position=2)]
        [int] $disp
    )
    if (($admin-eq 0) -or ($admin-eq $null)) {
        if (-not $adminCredential) {
            GetadminCredentials
        }
    }

    #Find an available letter to map with
    [array]$letters = "A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"
    $currentdrives = Get-PSDrive
    foreach ($letter in $letters) {
        if ($letter -notin $currentdrives.Name) {
            [array]$potential_letters += $letter
        }
    }
    $global:mapping_letter = $potential_letters | Get-Random -Count 1

    #Map the Drive
    $Uri = New-Object System.Uri($DrivePath)
    $IpAddress = Test-Connection ($Uri.Host) -Count 1 | Select -Expand IPV4Address | %{$_.ToString()}

    $PathName = $Uri.LocalPath -Replace $Uri.Host, $IpAddress

    #Remove Any Current Mapped Drive
    if (Test-Path "$($global:mapping_letter):") {
        Remove-PsDrive -Name $($global:mapping_letter) -PSProvider FileSystem -Scope Global -Force | Out-Null
        Start-Sleep -m 500
    }

    #Map the New Drive
    if (($notadmin -eq 0) -or ($notadmin -eq $null)) {
        #New-PsDrive -Name $($global:mapping_letter) -PSProvider FileSystem -Root $PathName -Credential $adminCredential -Scope Global -Persist | Out-Null
        net use "$($global:mapping_letter):" $PathName /user:$($adminCredential.username) /persistent:no | Out-Null
    } elseif ($notadmin -eq 1) {
        #New-PsDrive -Name $($global:mapping_letter) -PSProvider FileSystem -Root $PathName -Scope Global -Persist | Out-Null
        net use "$($global:mapping_letter):" $PathName /persistent:no | Out-Null
    }

    if (($disp -eq 1) -or ($disp -eq $null)) {
        ii "$($global:mapping_letter):"
    }
}
Ansgar Wiechers
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Nikolai Allen
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    Where does the `$notadmin` variable come from? – Ferrybig Sep 19 '19 at 06:06
  • You have a parameter `$admin`, but use a variable `$notadmin` in addition to `$admin` when mapping the drive. Also, your conditional for mapping the drive does not cover all possible cases, so there can be situations when no drive is being mapped. – Ansgar Wiechers Sep 19 '19 at 08:43
  • Side note: `explorer.exe "/e,${global:mapping_letter}"` might be a better approach than `Invoke-Item`. And using global variables is a bad idea to begin with. – Ansgar Wiechers Sep 19 '19 at 08:44
  • @AnsgarWiechers I mucked up renaming those variable names when posting to stackoverflow. Corrected initial question – Nikolai Allen Sep 23 '19 at 05:36
  • The first `if` statement in the function still has `$admin` instead of `$notadmin`. And the `if` statement where you're calling `net use` still doesn't cover situations where the value of `$notadmin` is neither `$null`, nor `0`, nor `1`. It'd be better to define `-notadmin` as a switch parameter or at least do parameter validation. Also, you haven't shown how you invoke the function. – Ansgar Wiechers Sep 23 '19 at 08:56

0 Answers0