Getting a free drive letter

Question

I saw the Get-NextFreeDrive function in this answer and I wondered if there was a more efficient way to do this. It appears that the function in the linked answ

Answer 1

Another way...

$DriveList = Get-PSDrive -PSProvider filesystem | foreach({($_.Root).Replace(":\","")})
$AllDrives = [char[]]([int][char]'E'..[int][char]'Z')
$NextDriveLetter = ($AllDrives | Where-Object { $DriveList -notcontains $_ } | Select-Object -First 1) + ":"

Answer 2

I found out that Test-Path evaluates my empty CD-Drive as False, here is another alternative that will compare every letter in the alphabeth until it finds one that doesn't exist in filesystem, then returns that drive as output.

$DriveLetter = [int][char]'C'
WHILE((Get-PSDrive -PSProvider filesystem).Name -contains [char]$DriveLetter){$DriveLetter++}
Write-Host "$([char]$Driveletter):"

Answer 3

$taken = Get-WmiObject Win32_LogicalDisk | Select -expand DeviceID
$letter = 65..90 | ForEach-Object{ [char]$_ + ":" }
(Compare-Object -ReferenceObject $letter -DifferenceObject $taken)[1].InputObject

Just for fun to shave an extra line of code (lol). If you wanted to be cloppy as heck you could skip instantiating variables and just pipe those directly into -Ref and -Diff directly, probably ought to be slapped for doing that though. :)

Selects [1] to avoid getting the A: drive just in case that might complicate matters.

Answer 4

At PowerShell Magazine, we ran a brain teaser contest to find out the shortest answer to your question. Check this:

http://www.powershellmagazine.com/2012/01/12/find-an-unused-drive-letter/

There are several answers but here is my fav one:

ls function:[d-z]: -n | ?{ !(test-path $_) } | random

Answer 5

I had to Write a function that works with Powershell V2.0. The following Function will Return the next available letter, it also can get an exclude letter as parameter:

Function AvailableDriveLetter ()
{
param ([char]$ExcludedLetter)
$Letter = [int][char]'C'
$i = @()
#getting all the used Drive letters reported by the Operating System
$(Get-PSDrive -PSProvider filesystem) | %{$i += $_.name}
#Adding the excluded letter
$i+=$ExcludedLetter
while($i -contains $([char]$Letter)){$Letter++}
Return $([char]$Letter)
}

Let's say Your OS reports drive-letters C:,E:,F: and G: as being used.

Running: $First = AvailableDriveLetter ,Will result in $First containing 'D'

Running: $Sec = AvailableDriveLetter -ExcludedLetter $First ,Will result in $Sec containing 'H'