Create/Set/modify registry key via powershell script

The following script does a check if a key exists, if an entry exists and if it has a predefined value, otherwise it updates the registry key with the desired value. Adapt the variables: $regPath (path to the registry key), $valueName (provide the name of the key), $requiredvalue (provide the desired value). Also set $type to the desired value (Dword, String, …)

<#
.DESCRIPTION	 
 This script will test existence of registry key, registry entry and	 
 its value to match with required value and provide the result 	 
 Author: Hansjoerg Morandell	 
 Website: inmyplace.info	 
 Version: 1.0.0	 
#>	 
# Provide registry key path 	 
$regPath = "HKCU:\Software" # full path here	 
# Provide registry entry display name 	 
$valueName = "<VALUENAME>"	 
# Provide registry entry expected value 	 
$requiredValue = "<REQUIREDVALUE>"	 
# Provide registry type	 
$type = "String"	 
$regkeyexists = Test-Path -Path $regPath	 
if ($regkeyexists) {	 
 # Check if registry entry named PbxServer exists	 
 $regentryexists = Get-ItemProperty -Path $regPath -Name $valueName -ErrorAction SilentlyContinue	 
 if ($regentryexists) {	 
 # If registry entry named PbxServer exists, then fetch its value	 
 $currentValue = Get-ItemProperty -Path $regPath | Select-Object -ExpandProperty $valueName -ErrorAction SilentlyContinue	 
 # Match $requiredValue registry entry value with required value	 
 if ($currentValue -eq $requiredvalue) {	 
 Write-Host "Reg value exists and matching the required value."	 
 } else {	 
 Write-Host "Reg value exists, but does not match the required value."	 
 Write-Host "Current value: $currentValue"	 
 Write-Host "Required value: $requiredValue"	 
 Set-ItemProperty -Path $regPath -Name $valueName -Value $requiredValue -Type $type -Force	 
 }	 
 } 	 
 else {	 
 New-ItemProperty -Path $regPath -Name $valueName -Value $requiredValue -Type $type -Force	 
 Write-Host "Registry value does not exist."	 
 }	 
} 	 
else {	 
 New-Item -Path $regPath -Force	 
 New-ItemProperty -Path $regPath -Name $valueName -Value $requiredValue -Type $type -Force	 
 Write-Host "Registry key does not exist. Creating it"	 
}

this can also be used in a custom detection script in Intune to check if a registry key exists and has a desired value:

<#
.DESCRIPTION
    This script will test existence of registry key, registry entry and
    its value to match with required value and provide the result 
    Author: Hansjoerg Morandell
    Website: inmyplace.info
    Version: 1.0.0
#>
# Provide registry key path 	 
$regPath = "HKCU:\Software" # full path here	 
# Provide registry entry display name 	 
$valueName = "<VALUENAME>"	 
# Provide registry entry expected value 	 
$requiredValue = "<REQUIREDVALUE>"	 
$regkeyexists = Test-Path -Path $regPath
if ($regkeyexists) {
   #Check if registry entry named $valueName exists
   $regentryexists = Get-ItemProperty -Path $regpath -Name $valueName -ErrorAction SilentlyContinue
   if ($regentryexists) {
   #If registry entry named PbxServer exists, then fetch its value
    $currentValue = Get-ItemProperty -Path $regpath | Select-Object -ExpandProperty $valueName -ErrorAction SilentlyContinue
    #Match PbxServer registry entry value with requied value
    if ($currentValue -eq $requiredvalue) {
            #Write-Host "Reg value exists and matching the required value."
			Write-Host "Success"
			Exit 0
        } else {
            #Write-Host "Reg value exists, but does not match the required value."
            #Write-Host "Current value: $currentValue"
            #Write-Host "Required value: $requiredValue"
			Exit 1
        }
    } 
    else {
        #Write-Host "Registry value does not exist."
		Exit 1
    }
} 
else {
    #Write-Host "Registry key does not exist."
	Exit 1
}