Prof. Powershell

To DIR, with Love; Or, How PowerShell 3 Will Improve Get-ChildItem

PowerShell 3 will make some much-needed improvements to the Get-ChildItem cmdlet.

• By Jeffery Hicks
• 01/17/2012

If you are like me and have a lot of experience with shells, you probably were a little frustrated with Windows PowerShell. For example, in the CMD shell it was very easy to run a command and return only folders:

C:\>dir test /ad
  Volume in drive C has no label.
  Volume Serial Number is A4BA-3EFF

  Directory of C:\test

12/12/2011 02:22 PM   <DIR>   .
12/12/2011 02:22 PM   <DIR>   ..
12/12/2011 02:21 PM   <DIR>   Folder$
12/12/2011 02:21 PM   <DIR>   Folder1
12/12/2011 02:21 PM   <DIR>   Folder2
12/12/2011 02:21 PM   <DIR>   Folder3
12/12/2011 02:21 PM   <DIR>   Folder4
12/12/2011 02:21 PM   <DIR>   Folder5
       0 File(s)            0 bytes
       8 Dir(s) 5,071,941,632 bytes free

But in PowerShell 2.0, we needed to resort to additional filtering using Where-Object:

PS C:\> dir test | where {$_.psiscontainer}

  Directory: C:\test

Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 12/12/2011 2:21 PM Folder1
d---- 12/12/2011 2:21 PM Folder2
d---- 12/12/2011 2:21 PM Folder3
d---- 12/12/2011 2:21 PM Folder4
d---- 12/12/2011 2:21 PM Folder5

Hardly efficient. Fortunately, PowerShell 3.0 has made dramatic improvements to Get-ChildItem, which is what the dir alias is pointing to.

Now if we only want directories we can use the –Directory parameter:

PS C:\test> dir -directory

Directory: C:\test

Mode         LastWriteTime  Length  Name
----         -------------  ------  ----
d----   12/12/2011 2:21 PM          Folder1
d----   12/12/2011 2:21 PM          Folder2
d----   12/12/2011 2:21 PM          Folder3
d----   12/12/2011 2:21 PM          Folder4
d----   12/12/2011 2:21 PM          Folder5

Or perhaps all we want are files:

PS C:\test> dir $env:temp -file | measure length -sum

Count    : 8
Average  :
Sum      : 478225
Maximum  :
Minimum  :
Property : Length

Get-Childitem also makes it easier to filter on attributes. For example, in the CMD shell we could do this:

C:\>dir /ah
  Volume in drive C has no label.
  Volume Serial Number is A4BA-3EFF

  Directory of C:\

02/16/2011  03:54 PM  <DIR>        $Recycle.Bin
07/14/2009  12:08 AM  <JUNCTION>   Documents and Settings [C:\Users]
12/02/2011  03:07 PM  <DIR>        ProgramData
08/21/2009  12:08 PM  <DIR>        Recovery
12/01/2011  08:31 PM  <DIR>        System Volume Information
            0 File(s)            0 bytes
            5 Dir(s) 5,071,945,728 bytes free

In PowerShell 3.0 we have parameters for Hidden, ReadOnly and System:

PS C:\test> dir c:\ -hidden

  Directory: C:\

Mode        LastWriteTime   Length  Name
----        -------------   ------  ----
d--hs   2/16/2011 3:54 PM           $Recycle.Bin
d--hs   7/14/2009 1:08 AM           Documents and Settings
d--h-   12/2/2011 3:07 PM           ProgramData
d--hs   8/21/2009 1:08 PM           Recovery
d--hs   12/1/2011 8:31 PM           System Volume Information

They can even be combined:

PS C:\test> dir c:\ -hidden -system

  Directory: C:\

Mode       LastWriteTime  Length  Name
----       -------------  ------  ----
d--hs  2/16/2011 3:54 PM          $Recycle.Bin
d--hs  7/14/2009 1:08 AM          Documents and Settings
d--hs  8/21/2009 1:08 PM          Recovery
d--hs  12/1/2011 8:31 PM          System Volume Information

Get-ChildItem also has a new parameter called –Attributes that gets very granular. Suppose I want to list just the compressed files in my Scripts folder:

PS C:\> dir c:\scripts -Attributes Compressed

  Directory: C:\scripts

Mode         LastWriteTime  Length  Name
----         -------------  ------  ----
-a---   12/2/2011 12:28 PM    1345  get-computers2.ps1
-a---   12/2/2011 12:42 PM    1666  get-computers3.ps1

PowerShell 3.0 has given us a much needed update to Get-ChildItem. All your version 2 scripts should continue to work, but I expect you’ll find these new features will make new scripting projects even easier. Be sure to look at full cmdlet help for Get-ChildItem.

Note: This information is based on PowerShell 3.0 CTP 2 and is subject to change -- and most likely will -- prior to release.