Test Registry Item

I've been doing some work lately involving the registry and Windows PowerShell. One of the tasks was to create new registry keys and entries. But because I wanted to some robustness, I wanted a way to verify if a given key or entry already existed.

Using Get-ItemProperty is the easy way to accomplish this.
[cc lang="PowerShell"]
PS S:\> get-itemproperty -Path HKCU:\jdhit\powershell -name test

PSPath : Microsoft.PowerShell.Core\Registry::HKEY_CURRENT_USER\jdhit\powershell
PSParentPath : Microsoft.PowerShell.Core\Registry::HKEY_CURRENT_USER\jdhit
PSChildName : powershell
PSDrive : HKCU
PSProvider : Microsoft.PowerShell.Core\Registry
Test : Foo
[/cc]
This is just fine if it exists, but a pain if it doesn't.
[cc lang="PowerShell"]
PS S:\> get-itemproperty -Path HKCU:\jdhit\powershell -name bogus
Get-ItemProperty : Property bogus does not exist at path HKEY_CURRENT_USER\jdhit\powershell.
At line:1 char:17
+ get-itemproperty <<<< -Path HKCU:\jdhit\powershell -name bogus + CategoryInfo : InvalidArgument: (bogus:String) [Get-ItemProperty], PSArgumentException + FullyQualifiedErrorId : System.Management.Automation.PSArgumentException,Microsoft.PowerShell.Commands.GetItemPr opertyCommand [/cc] So I ended up writing a wrapper function that returns True or False if the item exist. The function handles the error handling and also takes transactions into account, since that might be a factor when working with the registry. [cc lang="PowerShell"] Function Test-RegistryItem { <# .SYNOPSIS Test the the existence of a registry value .DESCRIPTION This command will determine if a given registry key exists. You must specify a registry path and the name of the key. .PARAMETER Path The registry path using the registry PSDrive format, ie HLKLM: .PARAMETER Property The property name to check. The parameter as an alias of Name. .PARAMETER UseTransaction Use an active transaction. This parameter is valid only when a transaction is in progress. For more information, see about_Transactions. .EXAMPLE PS C:\> test-itemproperty -Path "HKLM:\Software\Microsoft\Windows NT\CurrentVersion\Winlogon" -Property "Shell"
True

.INPUTS
[String]

.OUTPUTS
[Boolean]

.NOTES
NAME: Test-RegistryItem
AUTHOR: Jeffery Hicks
VERSION: 1.0
LASTEDIT: 10/01/2010

Learn more with a copy of Windows PowerShell 2.0: TFM (SAPIEN Press 2010)

.LINK
Get-ItemProperty
.LINK
https://jdhitsolutions.com/blog

#>

[cmdletbinding()]

Param (
[Parameter(Position=0,Mandatory=$True,HelpMessage="Enter a registry path using the PSDrive format.")]
[ValidateNotNullOrEmpty()]
[string]$Path,

[Parameter(Position=1,Mandatory=$True,HelpMessage="Enter a registry key name.")]
[ValidateNotNullOrEmpty()]
[Alias("name")]
[string]$Property,
[Switch]$UseTransaction
)
Write-Verbose ("Looking for {0} in {1}" -f $Property,$Path)
if (Test-Path $path)
{
if ($UseTransaction)
{
$item=Get-ItemProperty -Path $path -Name $property -ErrorAction "SilentlyContinue" -UseTransaction
} else
{
$item=Get-ItemProperty -Path $path -Name $property -ErrorAction "SilentlyContinue"
}

if ($item )
{
#display the item if using -Verbose
Write-Verbose ($item | select * | Out-String)
$True
}
else
{
Write-Verbose "Not found"
$False
}
}
else
{
Write-Warning "Failed to find $path"
$False
}

} #end function
[/cc]

The function uses the same parameters as Get-ItemProperty, although it adds an extra step to verify that the registry path exists by using Test-Path. Now, I can easily test for a key.
[cc lang="PowerShell"]
PS S:\> test-registryitem -Path HKCU:\jdhit\powershell -name bogus
False
PS S:\> test-registryitem -Path HKCU:\jdhit\powershell -name test
True
[/cc]

This makes my scripting much more efficient.
[cc lang="PowerShell"]
if (-not (Test-registryitem -path HKCU:\jdhit\powershell -name blog))
{
new-itemproperty -path HKCU:\jdhit\powershell -name blog -value https://jdhitsolutions.com/blog
}
[/cc]
Download Test-RegistryItem.ps1.

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