Skip to main content

How to filter out objects from Get-Volume that do not have a drive letter

By

While delivering a PowerShell class this week, I utilized the Get-Volume cmdlet to help me demonstrate filtering with Where-Object.  I came across a small problem.  Take a look at this output.

PS C:\> Get-Volume | Select -Property DriveLetter, FileSystem, Drivetype

 

               DriveLetter FileSystem                 DriveType               

               ----------- ----------                 ---------               

                         D NTFS                       Fixed                   

                         C NTFS                       Fixed                   

                         E NTFS                       Fixed                   

                           NTFS                       Fixed                   

                           NTFS                       Fixed                   

                           NTFS                       Fixed  

 

I attempted to filter out all DriveTypes that did not have a drive letter.

The following did not filter at all.

Get-Volume | Select -Property DriveLetter, FileSystem, Drivetype |

Where-Object {$_.DriveLetter -ne $Null}

 

Get-Volume | Select -Property DriveLetter, FileSystem, Drivetype |

Where-Object {$_.DriveLetter -ne ""}

 

Get-Volume | Select -Property DriveLetter, FileSystem, Drivetype |

Where-Object {$_.DriveLetter -ne " "}

 

Somewhere, there was a hidden character.  I first focused to the DriveLetter property on one of the objects that did not have a DriveLetter.

$D = Get-Volume | Select -Property DriveLetter, FileSystem, Drivetype

$D[4].DriveLetter

 

Next I decided to discover the ASCII code for this hidden character

[int][char]$D[4].DriveLetter

 

It was zero

Filtering for zero did not work.

Get-Volume | Select -Property DriveLetter, FileSystem, Drivetype |

Where-Object {$_.DriveLetter -ne 0} 

 

One of my students suggested looking at the escape characters.  Sure enough, `0 means NULL.  Take a look at this excerpt from About_Escape_Characters

The following special characters are recognized by Windows PowerShell:

 

        `0    Null

        `a    Alert

        `b    Backspace

        `f    Form feed

        `n    New line

        `r    Carriage return

        `t    Horizontal tab

        `v    Vertical tab

 

Now this works:

Get-Volume | Select -Property DriveLetter, FileSystem, Drivetype |

Where-Object {$_.DriveLetter -ne "`0"} 

 

 

 

Labels:

Comments

phuzz said…
Thank you! This little problem was driving me up the wall!
I even tried Get-Volume | Where-Object {![string]::IsNullOrEmpty($_.DriveLetter)} but I never thought it would be an escape character.
December 8, 2015 at 3:33 AM
Anonymous said…
Brilliant! Spent way to much time on this. Thank you very much.
March 2, 2016 at 12:25 PM
Post a Comment

Popular posts from this blog

Sticky Key problem between Windows Server 2012 and LogMeIn

By
This week I instructed my first class using Windows Server 2012 accessed via LogMeIn and discovered a Sticky Key problem every time you press the Shift key. Here is my solution to resolve this.  First off, in the Preferences of LogMeIn for the connection to the Windows Server, click General . Change the Keyboard and mouse priority to Host side user and click Apply at the bottom. On the Windows 2012 server, open the Control Panel – Ease of Access – Change how your keyboard works . Uncheck Turn on Sticky Keys . Click Set up Sticky Keys . Uncheck Turn on Sticky Keys when SHIFT is pressed five times . Click OK twice. If you are using Windows Server 2012 as a Hyper-V host, you will need to redo the Easy of Use settings on each guest operating system in order to avoid the Sticky Key Problem. Updated Information: March 20, 2013 If you continue to have problems, Uncheck Turn on Filter Keys .
6 comments
Read more

Where did a User’s Account Get Locked Out?

By
Updated: May 15, 2015 When this article was originally published, two extra carriage returns were add causing the code to malfunction.  The code below is correct.   My client for this week’s PowerShell class had a really interesting question. They needed to know where an account is being locked out at. OK, interesting. Apparently users hop around clients and forget to log off, leading to eventual lock out of their accounts. The accounts can be unlocked, but are then relocked after Active Directory replication. This problem is solved in two parts. The first one is to modify the event auditing on the network. The second part is resolved with PowerShell. The first part involves creating a group policy that will encompass your Domain Controllers. In this GPO, make these changes. Expand Computer Configuration \ Policies \ Windows Settings \ Security Settings \ Advanced Audit Policy Configuration \ Audit Policies \ Account Management Double click User Account Management C...
18 comments
Read more

Backup and Restore AD LDS with DSDBUTIL.exe

By
Active Directory Lightweight Directory Services allow you to create a directory service that allows applications to have access to user accounts, groups, and authentication similar to Active Directory Domain Services.  The big advantage here is that the schema of the directory service will not be bound by the rules of an Active Directory database.  Exchange 2007/2010, for example, use an instance of AD LDS on the Edge Transport Server to provide for user authentication from the internet.  Because your Active Directory database is not exposed to the internet, this is more secure. Applications will handle most of the dirty work should they require AD LDS.  You may want to make sure the database is being backed up and also have a restore plan in place.  Should the database become corrupt, the application that uses that database will fail.  This document will walk you through backing up and restoring an instance of AD LDS using the dsdbutil.exe command. Fi...
6 comments
Read more