PowerShell Professional

COM-unication

If you've written VBscripts, you're familiar with COM objects. Some COM objects work just fine in PowerShell, maybe better.

• By Jeffery Hicks
• 02/03/2009

Even though PowerShell is based on the .NET Framework, it supports legacy approaches to systems management including how it uses COM objects. If you've written VBscripts you've used COM objects for things like the FileSystemObject, the Shell and Network. The good news is that you can use those objects in PowerShell. The best news is that you can work with the objects interactively without a script!

Open a PowerShell prompt and type:

PS C:\> $shell=new-object -COM "wscript.shell"

Now pipe $shell to Get-Member and you should see all of the methods and properties you were use to working with in VBScript. Try this:

PS C:\> $shell.specialfolders

You should see all of the special Windows folders. Unfortunately not all COM functionality translates properly to PowerShell. In VBScript I could use $shell.specialfolders("desktop") to retrieve just the desktop folder, but not in PowerShell. But you can execute methods:

PS C:\> $Shell.regread("HKLM\Software\microsoft\Windows NT\CurrentVersion\RegisteredOwner")
Admin
PS C:\> $Shell.regwrite("HKLM\Software\microsoft\Windows NT\CurrentVersion\RegisteredOwner","Jeff Hicks")
PS C:\> $Shell.regread("HKLM\Software\microsoft\Windows NT\CurrentVersion\RegisteredOwner")
Jeff Hicks

Having access to these methods provides a transition if you need it in moving completely to PowerShell. And frankly, sometimes the older ways still work just fine:

PS C:\> $network=new-object -COM "wscript.network"
PS C:\> $network.EnumNetworkDrives()
P:
\\pluto\files

Or the COM objects offer functionality that you don't have in PowerShell or perhaps an easier approach:

PS C:\> $fso=new-object -com "scripting.filesystemobject"
PS C:\> $fso.drives | where {$_.drivetype -eq 2} | Select Path,AvailableSpace,FreeSpace,TotalSize

Path   AvailableSpace  FreeSpace   TotalSize
----   --------------  ---------   ---------
C:     136613888       136613888   4285337600
E:     256651264       256651264   1069253632

Remember we're still working with object so we can leverage the PowerShell pipeline and take advantage of the best of both worlds. You'll also discover that if you want to work with other applications such as Microsoft Word, Microsoft Excel of even Apple's iTunes you can with PowerShell and its support for COM objects. Create a COM object, pipe it to Get-Member to discover its methods and properties and start using it immediately in PowerShell without writing a single line of script.