Strange behavior with Hyper-V module from Codeplex

There are some situations where you want to boot a remote computer that’s powered off, but don’t have the tools to do that. For example: Microsoft SCCM allows you to boot a remote computer (wake it up from power off) to install Windows Updates. If you don’t have SCCM there are thousands of alternative software solutions, but we cannot trust most of them, right?

Look no further! We can power on remote computers through PowerShell! The script demonstrates how to remote boot a PC with a UDP packet we’re creating through the System.Net.Sockets.UdpClient programming interface (part of dot Net).

Just replace the MAC-address with the address of the computer you want to boot, start the script, and boot!

$MacAddress = [byte[]](0x00, 0x25, 0xB3, 0x0D, 0xA8, 0xF9)
$UDPclient = New-Object System.Net.Sockets.UdpClient
$UDPclient.Connect(([System.Net.IPAddress]::Broadcast),4000)
$packet = [byte[]](,0xFF * 102)
6..101 | foreach { $packet[$_] = $MacAddress[($_%6)]}
$UDPclient.Send($packet, $packet.Length)

PowerShell provides some commands to manipulate services, but that doesn’t work on remote computers! The script you can find below demonstrates that stopping a service on a remote computer using Stop-Service is not working.

First I verify that the MSDTC service is running on the local machine and a remote machine: server2. If I want to stop the service on both machines I use the Stop-Service cmdlet. But this command doesn’t work on server2 when I’m piping the output from Get-Service to Stop-Service!  :-(

There are two solutions. The first is you can use the InputObject parameter as part of Stop-Service.

You can also use WMI to stop a remote service.  Just retreive the specific service from a remote computer by using the Get-WmiObject cmdlet and use the StopService method to stop the service.

WMI is intended to work remote so this command gives the correct result!  :-)

"Verifying services"
Get-Service MSDTC
Get-Service MSDTC -computer server2
"Stopping services"
Get-Service MSDTC | Stop-Service
Get-Service MSDTC -computer server2 | Stop-Service   # Stop-Service does not accept pipelined input!
"Verifying services."
Get-Service MSDTC
Get-Service MSDTC -computer server2
"Stopping remote service, alternative"
Stop-Service -InputObject (Get-Service MSDTC -ComputerName server2)
"Stopping remote service using WMI"
(Get-WmiObject win32_service -computer server2 | Where { $_.name -eq 'MSDTC' }).stopservice()

Thanks to Martin Tengvall for pointing out the -InputObject variant.

It’s possible to compress a folder or file since Windows NT. It’s a feature of the NTFS-filesystem. Normally we would do that on the properties of the folder or file in the Windows Explorer, but you can do this with PowerShell too! Just use this command:

Invoke-WmiMethod -Path "Win32_Directory.Name='C:\Test'" -Name compress

And to Uncompress the same folder, use this command:

Invoke-WmiMethod -Path "Win32_Directory.Name='C:\Test'" -Name uncompress

We’re talking about NTFS compression here, not the ZIP-feature introduced in Windows XP and later. You can notice that the folder is compressed by the blue color of the folder in Windows Explorer. Or you can open the properties of the folder to see whether the size on disk is smaller than the normal size. Do not try to compress items that are already compressed, like pictures (JPG…), music (MP3…), video (AVI, MPG…).

When you use WMI to execute operating system functions like this, you get a return value. When the return value is 0 (zero) this means the command functioned. Other return values can mean different things (read-only, no disk space, no permissions,…). In general: when we’re executing WMI-commands we’re allways checking the return value. You could implement it like this:

$a = Invoke-WmiMethod -Path "Win32_Directory.Name='C:\Test'" -Name compress
If ($a.returnvalue) -eq 0 { "Items successfully compressed" } else { "Something went wrong!" }

The other day I stumbled upon a nice PowerShell command to use the speech API found on modern Windows Operating Systems. With this script PowerShell can talk to you! Great for situations where you want to hear about the progress of your script. Or maybe to tell you there’s an alert instead of showing the alert. Here’s the script:

$a = New-Object -COM SAPI.SpVoice
$a.speak("I'm completely operational, and all my circuits are functioning perfectly.")