Working with Registry Entries

Because registry entries are properties of keys and, as such, cannot be directly browsed, we need to take a slightly different approach when working with them.

Listing Registry Entries

There are many different ways to examine registry entries. The simplest way is to get the property names associated with a key. For example, to see the names of the entries in the registry key HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion, use Get-Item. Registry keys have a property with the generic name of "Property" that is a list of registry entries in the key. The following command selects the Property property and expands the items so that they are displayed in a list:

PS> Get-Item -Path Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion | Select-Object -ExpandProperty Property
DevicePath
MediaPathUnexpanded
ProgramFilesDir
CommonFilesDir
ProductId

To view the registry entries in a more readable form, use Get-ItemProperty:

PS> Get-ItemProperty -Path Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion


PSPath              : Microsoft.PowerShell.Core\Registry::HKEY_LOCAL_MACHINE\SO
                      FTWARE\Microsoft\Windows\CurrentVersion
PSParentPath        : Microsoft.PowerShell.Core\Registry::HKEY_LOCAL_MACHINE\SO
                      FTWARE\Microsoft\Windows
PSChildName         : CurrentVersion
PSDrive             : HKLM
PSProvider          : Microsoft.PowerShell.Core\Registry
DevicePath          : C:\WINDOWS\inf
MediaPathUnexpanded : C:\WINDOWS\Media
ProgramFilesDir     : C:\Program Files
CommonFilesDir      : C:\Program Files\Common Files
ProductId           : 76487-338-1167776-22465
WallPaperDir        : C:\WINDOWS\Web\Wallpaper
MediaPath           : C:\WINDOWS\Media
ProgramFilesPath    : C:\Program Files
PF_AccessoriesName  : Accessories
(default)           :

The Windows PowerShell-related properties for the key are all prefixed with "PS", such as PSPath, PSParentPath, PSChildName, and PSProvider.

You can use the "." notation for referring to the current location. You can use Set-Location to change to the CurrentVersion registry container first:

Set-Location -Path Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion

Alternatively, you can use the built-in HKLM PSDrive with Set-Location:

Set-Location -Path hklm:\SOFTWARE\Microsoft\Windows\CurrentVersion

You can then use the "." notation for the current location to list the properties without specifying a full path:

PS> Get-ItemProperty -Path .
...
DevicePath          : C:\WINDOWS\inf
MediaPathUnexpanded : C:\WINDOWS\Media
ProgramFilesDir     : C:\Program Files
...

Path expansion works the same as it does within the file system, so from this location you can get the ItemProperty listing for HKLM:\SOFTWARE\Microsoft\Windows\Help by using Get-ItemProperty -Path ..\Help.

Getting a Single Registry Entry

If you want to retrieve a specific entry in a registry key, you can use one of several possible approaches. This example finds the value of DevicePath in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion.

Using Get-ItemProperty, use the Path parameter to specify the name of the key, and the Name parameter to specify the name of the DevicePath entry.

PS> Get-ItemProperty -Path HKLM:\Software\Microsoft\Windows\CurrentVersion -Name DevicePath


PSPath       : Microsoft.PowerShell.Core\Registry::HKEY_LOCAL_MACHINE\Software\
               Microsoft\Windows\CurrentVersion
PSParentPath : Microsoft.PowerShell.Core\Registry::HKEY_LOCAL_MACHINE\Software\
               Microsoft\Windows
PSChildName  : CurrentVersion
PSDrive      : HKLM
PSProvider   : Microsoft.PowerShell.Core\Registry
DevicePath   : C:\WINDOWS\inf

This command returns the standard Windows PowerShell properties as well as the DevicePath property.

	Note:
	Although Get-ItemProperty has Filter, Include, and Exclude parameters, they cannot be used to filter by property name. These parameters refer to registry keys—which are item paths—and not registry entries—which are item properties.

Another option is to use the Reg.exe command line tool. For help with reg.exe, type reg.exe /? at a command prompt. To find the DevicePath entry, use reg.exe as shown in the following command:

PS> reg query HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion /v DevicePath

! REG.EXE VERSION 3.0

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
    DevicePath  REG_EXPAND_SZ   %SystemRoot%\inf

You can also use the WshShell COM object as well to find some registry entries, although this method does not work with large binary data or with registry entry names that include characters such as "\"). Append the property name to the item path with a \ separator:

PS> (New-Object -ComObject WScript.Shell).RegRead("HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\DevicePath")
%SystemRoot%\inf

Creating New Registry Entries

To add a new entry named "PowerShellPath" to the CurrentVersion key, use New-ItemProperty with the path to the key, the entry name, and the value of the entry. For this example, we will take the value of the Windows PowerShell variable $PSHome, which stores the path to the installation directory for Windows PowerShell.

You can add the new entry to the key by using the following command, and the command also returns information about the new entry:

PS> New-ItemProperty -Path HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion -Name PowerShellPath -PropertyType String -Value $PSHome


PSPath         : Microsoft.PowerShell.Core\Registry::HKEY_LOCAL_MACHINE\SOFTWAR
                 E\Microsoft\Windows\CurrentVersion
PSParentPath   : Microsoft.PowerShell.Core\Registry::HKEY_LOCAL_MACHINE\SOFTWAR
                 E\Microsoft\Windows
PSChildName    : CurrentVersion
PSDrive        : HKLM
PSProvider     : Microsoft.PowerShell.Core\Registry
PowerShellPath : C:\Program Files\Windows PowerShell\v1.0

The PropertyType must be the name of a Microsoft.Win32.RegistryValueKind enumeration member from the following table:

PropertyType Value	Meaning
Binary	Binary data
DWord	A number that is a valid UInt32
ExpandString	A string that can contain environment variables that are dynamically expanded
MultiString	A multiline string
String	Any string value
QWord	8 bytes of binary data

	Note:
	You can add a registry entry to multiple locations by specifying an array of values for the Path parameter:

New-ItemProperty -Path HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion, HKCU:\SOFTWARE\Microsoft\Windows\CurrentVersion -Name PowerShellPath -PropertyType String -Value $PSHome

You can also overwrite a pre-existing registry entry value by adding the Force parameter to any New-ItemProperty command.

Renaming Registry Entries

To rename the PowerShellPath entry to "PSHome," use Rename-ItemProperty:

Rename-ItemProperty -Path HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion -Name PowerShellPath -NewName PSHome

To display the renamed value, add the PassThru parameter to the command.

Rename-ItemProperty -Path HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion -Name PowerShellPath -NewName PSHome -passthru

Deleting Registry Entries

To delete both the PSHome and PowerShellPath registry entries, use Remove-ItemProperty: