Powershell:Append a new value to existing Multistring Registry item

copy the below sample to a file called SetRegKeyEx1.ps1

then run it as follows   ( the script adds a testkey to your registry – change the key values as needed )

powershell.exe -ExecutionPolicy RemoteSigned .\SetRegKeyEx1.ps1

#

[string]$script:psMultiSz

if (!(Test-Path HKLM:\System\CurrentControlSet\Newkey)) { md HKLM:\System\CurrentControlSet\Newkey }

New-ItemProperty HKLM:\System\CurrentControlSet\Newkey TestValue -value “One”,”Two”,”Three” -propertyType Multistring

#  ///////// Get the main key /////////////////////////////////////
$key = Get-Item HKLM:\System\CurrentControlSet\NewKey

$keytwo = Get-ItemProperty $key.PSPath “TestValue”

$psMultiSz = $Keytwo.(“TestValue”)

Write-Host “this is current value of TestValue-> $psMultiSz`n”

#  ///////// Add a new value to the multistring value /////////////////////////////////////

$psMultiSz += “four”

Set-ItemProperty HKLM:\SYSTEM\CurrentControlSet\NewKey -name “TestValue” -Value $psMultiSz -Type MultiString

Write-Host “new value added to TestValue key`n”

#  ///////// Retrieve the new value  /////////////////////////////////////

$key = Get-Item HKLM:\System\CurrentControlSet\NewKey

$keytwo = Get-ItemProperty $key.PSPath “TestValue”

$psMultiSz = $Keytwo.(“TestValue”)

write-host “this is the new value of TestValue -> $psMultiSz`n”