There is an entire library of free PowerShell scripts for Hyper-V 2008r2 management at: www.codeplex.com/psHyperV.
There is an entire library of Hyper-V Cmdlets in Windows PowerShell 3.0 for Hyper-v Server 20012
There are helpful, free, Hyper-V scripts available on the Script Center Gallery.

You can find many, many more Hyper-V scripts on the web, including: 

• New! Powershellscript to get a detailed report of your Hyper-v Vhost and VM's hosted on it, works for standalone Datacenter 2012 Servers
• New! Powersehllscript to easily create hyper-v Vm in stand alone Datacenter 2012 Servers
• New! Powershell Script to Shutdown and Export Hyper-V VMs on Windows Server 2012, one at a time
• New! PS - Export a virtual machine by Virtual PC Guy
• Detect which virtual machines are using Virtual Machine Device Queues with Hyper-V (http://www.windowsitpro.com/article/virtualization2/virtual-machines-device-queues-vmdq-hyperv-142119) by John Savill
• New! Skimming a Hyper-V Service Event log with PowerShell
• New! PS - Deleting a snapshot sub-tree by Virtual PC Guy
• New! PS - Script to get virtual machine processorsfrom a VM- Virtual PC Guy
• New! PS- Take a Snapshot  by Virtual PC Guy
• New! PS - List snapshots  by Virtual PC Guy
• New! PS - Apply snapshot by Virtual PC Guy
• New!  PS - Delete snapshot by Virtual PC Guy
• New! Identify the Physical Host of a Virtual Server - Santhosh Sivarajan (MVP)
• New! Scripts for DPM 2010 procedure for protecting a VM
• New! Automating Update/Patch process using System Center Virtual Machine Manager 2012 by kandavel1
• Codeplex PowerShell script to manage Hyper V virtual machines (start stop save suspend pause shutdown snapshot)
• PowerShell Script to set up non-admin access to Hyper-V by Ben Armstrong.
• Create a Hyper-V VMMS self-signing certificate that doesn’t expire until 2050 by Jeff Patterson, MSFT. Note: This script requires Makecert.exe to generate the certificate
• PowerShell Script to Check IC version by Stefan Wernli.
• WMI Helper Module for Windows PowerShell Version 6 by the Scripting Guy
• Checking Integration Components version on Hyper-V RTM by Cristian Edwards
• Check CSV Free Disk Space by the Clustering and NLB Team
• PS - Check UpTime from localhost and/or remote Computer
• PS- 'Map' utility to display drive information by bigteddy
• Find Virtualization Hosts (computers with Hyper-V enabled) by John Howard
• Enable Processor Compatibility with PowerShell by Ben Armtrong
• Change Parent VHD in Windows VirtualPC, Virtual Server or Hyper-V by Marcelo Sincic. Change the Parent VHD after move virtual disk.
• Enumerate the virtual machines and their properties in hyper-v by James Anderson. Enumerate the virtual machines and their properties in hyper-v using WMI.
• Create virtual machines for VDI by RemoteDesktopServices. This script creates virtual machines for use with MS VDI. The created virtual machines are automatically configured for MS VDI. A script is also output that can be run on Connection Broker to assign the created virtual machines to users or pools.
• List virtual machines in a hyper-v host cluster by RemoteDesktopServices. This script gets the list of virtual machine(s) on one or all of the nodes of a Hyper-V cluster.
• Hyper-V Certificate Validation Workaround by Stefan J. Wernli. If certificate verification delays are causing long VM start up time, run this script to set up a workaround using Hyper-V registry key for certificate validation. This should allow faster VM start when experiencing network issues that delay validation.
• Script to Change ‘Unidentified network’ from Public to Work in WS2K8 R2 by tonysoper. Set the category of an Unidentified network in Windows 7/WS2K8R2.
• Reset MAC Address by tonysoper. Script to reset MAC addresses on VMs.
• PS - Shut Down VM by tonysoper. PS 2.0 Script to Shut Down VMs.
• PS Script to Check Hypervisor Heartbeat by tonysoper. Checks if Hypervisor is running.
• PS - Modify VLAN Settings by tonysoper .PS 2.0 script to modify virtual networking settings on your virtual machines.
• PS - Convert VHD by tonysoper. PS 2.0 script to convert VHDs.
• PS - Change VM State by tonysoper. PS 2.0 script to change state on VMs.
• PS - Compact VHD by tonysoper. PS 2.0 script to compact VHDs.
• PS - List VMs by tonysoper. PS script to list VMs from Thomas Lee.
• PS - Change ISO by tonysoper. PS 2.0 script to change the ISO in the virtual DVD Drive.
• PS - Create Dynamic VHD by tonysoper. PS 2.0 script to create dynamic VHDs.
• PS - Create VM by tonysoper. PS 2.0 script to create VMs
• PS - New VM by Michael Greene. Creat new VMs 
• PowerShell Script to extract the UUID of a particular server by tonysoper. Here’s a sample PowerShell Script to extract the UUID of a particular server.
• PS - Apply Snapshot by tonysoper. PS 2.0 script to apply snapshots to VMs.
• PS - Loopback Mount a VHD by tonysoper. PS 2.0 script to loopback mount a VHD.
• Detect VM by tonysoper. Need to detect if something is running inside a VM? John Kelbely shares how; read more at: http://blogs.technet.com/tonyso/archive/2009/08/20/hyper-v-how-to-detect-if-you-are-inside-a-vm.aspx.
• VBSCript to Set Serial Number for a VM by tonysoper. Example script for setting the serial number of a Virtual PC 2007 virtual machine.
• VB - NICHA by tonysoper. VB script to monitor the NIC used by a virtual machine in a cluster.
• PS - Expand VHD by tonysoper. PS 2.0 script to expand VHDs.
• PS - Connect Switch to NIC by tonysoper. PowerShell 2.0 script for connecting a virtual switch to a physical NIC on the HOST.
• PS - Connect Switch to VM by tonysoper. PS 2.0 script to connect a virtual switch to a VM.
• PS - Snapshot a VM by tonysoper. PS 2.0 script to take a snapshot of a VM.
• PS - Remove vNIC by tonysoper. PS 2.0 script to remove a virtual NIC from a VM.
• PS Check IC Version by tonysoper. PS 2.0 script to Check if VM Integration components/integration services are up to date .
• PS - Get a Custom KVP by tonysoper. PS 2.0 script to Get a Custom KVP.
• PS - List Snapshots by tonysoper. 
• PS - Create VSwitch by tonysoper. PS 2.0 script to create a virtual switch.
• PS - Create Fixed VHD by tonysoper .PS 2.0 script to create fixed VHDs.
• Script to Reconnect A Parent Disk by tonysoper. PowerShell script for calling ReconnectParentVirtualHardDisk. Use it if you are having trouble in the UI when you are trying to reconstruct a broken chain of snapshots. Copy it locally, rename it to .ps1, and then run it from an elevated poweshell command prompt.
• PS - Create Differencing VHD by tonysoper. PS 2.0 script to create a differencing.
• PS - Delete VM by tonysoper. PS 2.0 to delete VMs.
• PS - Set a Custom KVP by tonysoper. PS 2.0 script to set a custom VM KVP.
• PS - Merge VHDs by tonysoper. PS 2.0 script to merge VHDs.
• PS - Get Intrinsic KVPs by tonysoper. PS 2.0 script to get intrinsic KVP.
• VBS: Hyper-V Export VM, Export VM — Config Only, Import VM. (Also see theoretical details for export and import: Part 1, Part 2, Part 3).
• Nic HA Sample Script by robertvi.  Use this script to monitor the NIC used by a Virtual Machine in a Hyper-V cluster.
• Evac-VMs.ps1 by davidr. PowerShell for evacuating VMs on host shutdown.
• Script to attach a USB device to a virtual machine [VPC] by Ben Armstrong http://blogs.msdn.com/b/virtual_pc_guy/archive/2011/01/18/script-to-attach-a-usb-device-to-a-virtual-machine-vpc.aspx
   

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See Also

• Hyper-V Portal