[Powershell] Playing with registry keys in powershell

I've had to read and write some registry keys from my management pack to implement a functionnality for debugging purpose - all events are created in in the Operations Manager Event log.

Here are the differents functions that can be usefull :

• CheckIfRegistryKeyExists : create event 200 (Information or Error) depending of the result
• ReadRegistryKey : Read the key value and write information event 200
• WriteRegistryKey : Write the key value and write information event 200
• Write-ErrorInfo : create error event 500
• Write-DebugInfo : create Information event 100

Copy the code below in a  ReadRegistryKey.ps1 file for example

1. param ($RegistryKeyPath, $KeyName, $KeyValue, $Debug)
2. if ($debug -ne "true"){$debug = [bool]$false}else{$debug = [bool]$true}
3. $Script:API             = new-object -comObject "MOM.ScriptAPI"
4. $Script:Bag             = $Script:API.CreatePropertyBag()
5. $Script:LOG_ERROR       = 1
6. $Script:LOG_WARNING     = 2
7. $Script:LOG_INFORMATION = 4
8. $Script:ScriptName      = "ReadRegistryKey.ps1"
9. $Script:Arguments       = "Received Arguments:`RegistryKeyPAth = $RegistryKeyPath `rKeyName = $KeyName `rDebug = $debug"
10. #------------------------------------------------------------------------------------------
11. Function CheckIfRegistryKeyExists($KeyPath,$KeyName)
12. {
13.  $KeytoRead = $KeyPath
14.  $KeytoReadName = $KeyName
15.  $a = (Get-ItemProperty -path registry::$KeytoRead).$KeytoReadName -eq $null
16.  if ($a -eq "false")
17.   {
18.   $Script:API.LogScriptEvent("CheckIfRegictyryKeyExists",200,$Script:LOG_ERROR,"`r$KeyPath\$KeyName doesn't exist !")
19.   }
20.  else
21.   {
22.   $Script:API.LogScriptEvent("CheckIfRegictyryKeyExists",200,$Script:LOG_INFORMATION,"`r$KeyPath\$KeyName exists.")
23.   }
24. }
25. #------------------------------------------------------------------------------------------
26. function ReadRegistryKey($KeyPath,$KeyName)
27. {
28.     $Script:API.LogScriptEvent("$ScriptName",200,$Script:LOG_INFORMATION,"`r$KeyPath\$KeyName ")
29.  $KeytoRead = $KeyPath
30.  $KeytoReadValue = $KeyName
31.  $a = Get-ItemProperty -path registry::$KeytoRead -name $KeytoReadValue
32.  $ReadValue = $a.$KeytoReadValue
33.  $ReadValue
34. }
35. #------------------------------------------------------------------------------------------
36. function WriteRegistryKey($KeyPath,$KeyName,$KeyValue)
37. {
38.  $Script:API.LogScriptEvent("$ScriptName",200,$Script:LOG_INFORMATION,"`r$KeyPath\$KeyName with value $KeyValue is created")
39.  $KeytoRead = $KeyPath
40.  $KeytoReadValue = $KeyName
41.  $Value = $KeyValue
42.  $a = Set-ItemProperty -path registry::$KeytoRead -name $KeytoReadValue -Value $Value
43.  $a.$KeytoReadValue
44. }
45. #------------------------------------------------------------------------------------------
46. function Write-DebugInfo([string] $msg)
47. {
48.     if ($debug)
49.     {
50.         $Script:API.LogScriptEvent("$ScriptName",100,$Script:LOG_INFORMATION,"`r$Arguments`r`r$msg")
51.     }
52. }
53. #------------------------------------------------------------------------------------------
54. function Write-ErrorInfo([string] $msg)
55. {
56.     if ($debug)
57.     {
58.     $Script:API.LogScriptEvent("$ScriptName",500,$Script:LOG_ERROR,"`r$Arguments`r`r$msg")
59.  }
60. }
61. #------------------------------------------------------------------------------------------
62. # MAIN CODE START HERE
63. #------------------------------------------------------------------------------------------
64. # Use this line to Read the registry key
65. ReadRegistryKey $RegistryKeyPath $KeyName
66. # Use this line to Create the registry key with its value
67. WriteRegistryKey $RegistryKeyPath $KeyName $KeyValue
68. # Use this line to check if key exist
69. CheckIfRegistryKeyExists $RegistryKeyPath $KeyName

Then is a powershell command shell, just launch the ReadRegistryKey.ps1 with the parameters like :
> C:\scripts\ReadRegistryKey.ps1 "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Microsoft Operations Manager\Debugging" "ForTestingPurpose" "ValueToSet" "true"

When the HKLM\SOFTWARE\Microsoft\Microsoft Operations Manager\Debugging\ForTestingPurpose key doens't exist :

• ReadRegistryKey function will return

Case : key tested exists :

Case key doens't exist : To be implemented since the code return error in powershell or just use the CheckRegistryKey function before.

Get-ItemProperty : Property ForTestingPurpose1 does not exist at path HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft Operations Manager\Debugging.
At C:\scripts\ReadRegistryKey.ps1:35 char:23
+     $a = Get-ItemProperty  <<<< -path registry::$KeytoRead -name $KeytoReadValue

• Write registry key will create the key and return :

• Checking the registry key can return 2 states :

Key doens't exist

And also Key exists :

 Hope this will be helpful.

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