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 answer keeps going through all the letters even if it has already found a free drive letter.

Answer 1

Here's what I came up with. I need the last available drive letter from A to Z.

$AllLetters = 65..90 | ForEach-Object {[char]$_ + ":"}
$UsedLetters = get-wmiobject win32_logicaldisk | select -expand deviceid
$FreeLetters = $AllLetters | Where-Object {$UsedLetters -notcontains $_}
$FreeLetters | select-object -last 1

• This gets an array of letters A..Z
• Then gets an array of the letters already in use from WMI
• Next produces an array of letters not in use using the comparison operator -notcontains
• Finally outputs a single letter.