Prof. Powershell
Prof. PowerShell: COM-munication
Some COM objects work just fine in PowerShell -- maybe better.
- By Jeffery Hicks
- 04/01/2009
Even though PowerShell is based on .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, too. 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 used to working with in VBScript. Try this:
PS C:\> $shell.specialfolders
You should see all 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\Soft
ware\microsoft\Windows
NT\CurrentVersion\Registere
dOwner")
Admin
PS C:\> $Shell.regwrite("HKLM\Soft
ware\microsoft\Windows
NT\CurrentVersion\Registere
dOwner","Jeff Hicks")
PS C:\> $Shell.regread("HKLM\Soft
ware\microsoft\Windows
NT\CurrentVersion\Registere
dOwner")Jeff Hicks
Having access to these methods provides a transition to moving completely to PowerShell. But sometimes the older ways still work just fine:
PS C:\> $network=new-object -COM "wscript.net
work"
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.filesyste
mobject"
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 objects, 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 apps -- such as Word, Excel or even Apple 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.
About the Author
Jeffery Hicks is an IT veteran with over 25 years of experience, much of it spent as an IT infrastructure consultant specializing in Microsoft server technologies with an emphasis in automation and efficiency. He is a multi-year recipient of the Microsoft MVP Award in Windows PowerShell. He works today as an independent author, trainer and consultant. Jeff has written for numerous online sites and print publications, is a contributing editor at Petri.com, and a frequent speaker at technology conferences and user groups.