Manning Deal of the Day–31 August 2015
Published August 30, 2015Deal of the Day August 31: Half off my book Learn Active Directory Management in a Month of Lunches. Use code dotd083115au at https://manning.com/books/learn-active-directory-management-in-a-month-of-lunches
Learn ConfigMgr 2012 in a Month of Lunches and Learn SQL Server Administration in a Month of Lunches also included
PowerShell User Group meeting in Manchester
Published August 28, 2015The UK PowerShell User Group was the World’s first user group dedicated to PowerShell. Its been in hibernation for the last few years but Ryan Yates is bringing it back to life.
He’s set up a meeting in Manchester for Tuesday 13 October 2016. See http://www.kilasuit.org/Blog/Post/18/Coming-to-Manchester-October-13th---Get-PSUGUKMan
for details.
If you’re in the area I’d recommend you get there if you can
PowerShell Summit Europe 2015 final schedule
Published August 27, 2015The schedule for the PowerShell Summit Europe 2015 has been finalised. See the event site at http://eventmgr.azurewebsites.net/event/home/PSEU15#schedule
PowerShell gallery security
Published August 26, 2015There are a number of concerns with pulling code from the Internet e.g. code quality and whether it contains malicious actions.
The PowerShell gallery has implemented a couple of features that should help.
All modules have to meet a minimum quality standard as outlined here - http://blogs.msdn.com/b/powershell/archive/2015/08/07/powershell-gallery-new-security-scan.aspx
You can also use Save-Module to download the module to a safe location so you can inspect the contents.
Creating JSON from a hash table
Published August 19, 2015A question on the forum was asking about creating a JSON structure for use with a REST API.
The original has table looked like this
$body = @{
auth_token = "$auth_token"
items = @{
label = "server1"
value = "OK"
label = "server2"
value = "OK"
}
}
This fails because you can’t have duplicate keys in a hash table.
One way to create the JSON is like this
$items = @()
$items += @{label = "server1"; value = "OK"}
$items += @{label = "server2"; value = "OK"}
$body = New-Object -TypeName PSOBject -Property @{
auth_token = "$auth_token"
Items = $items
}
ConvertTo-Json -InputObject $body
which gives:
{
"Items": [
{
"value": "OK",
"label": "server1"
},
{
"value": "OK",
"label": "server2"
}
],
"auth_token": ""
}
The items are created by adding hah tables to a pre-existing hash table. You’re creating a hashtable of hash tables.
If you need to control the order of values you need an ordered hash table to use with New-Object
$items = @()
$items += @{label = "server1"; value = "OK"}
$items += @{label = "server2"; value = "OK"}
$props = [ordered]@{
auth_token = "$auth_token"
Items = $items
}
$body = New-Object -TypeName PSOBject -Property $props
ConvertTo-Json -InputObject $body
which gives
{
"auth_token": "",
"Items": [
{
"value": "OK",
"label": "server1"
},
{
"value": "OK",
"label": "server2"
}
]
}
Passing data into Jobs
Published August 18, 2015PowerShell jobs are a powerful tool for running processes in the background. You have to remember that a PowerShell job runs in a separate process that only exists for the duration of the job. The results are returned to your process when the job finishes.
A user on the forum asked about passing variables into jobs. He’d done this:
$w = '1..10'
Invoke-Expression $w
and got the expected result
1
2
3
4
5
6
7
8
9
10
He then tried this
Start-Job -ScriptBlock { Invoke-Expression $w}
But the job said
Cannot bind argument to parameter 'Command' because it is null.
+ CategoryInfo : InvalidData: (:) [Invoke-Expression], ParameterBindingValidationException
+ FullyQualifiedErrorId : ParameterArgumentValidationErrorNullNotAllowed,Microsoft.PowerShell.Commands.InvokeExpre
ssionCommand
+ PSComputerName : localhost
Irrespective of whether using Invoke-Expression is a good idea and I’ll cover that in a future post the job fails because its failing to find $w because the job is running in a separate PowerShell process and $w doesn’t exist.
The simplest answer is to make the job self contained
Start-Job -ScriptBlock { $w = '1..10'; Invoke-Expression $w}
Everything is in the script block passed to the job and therefore passed to the new PowerShell process.
Alternatively, you can pass the variable $w into the script block
Start-Job -ScriptBlock { param($w) Invoke-Expression $w} -ArgumentList $w
You need to define a param block on the script block and pass the $w variable to it using the –Argumentlist parameter on start-job.
Another option introduced with PowerShell 3.0 us the $using scope modifier
Start-Job -ScriptBlock { Invoke-Expression $using:w}
Which is another way to say use the $w variable from the current scope
You can find out more on $using from about_scopes, about_Remote_Variables
WinOps conference
Published August 11, 2015The WinOps conference will take place 22 September 2015 in London.
Details from http://winops.org/
Its all about “Windows in a DevOps world”
Windows 10 and PSScriptAnalyzer
Published August 10, 2015if you were wondering where the PSScriptanalyzer module was in Windows 10 RTM - its not there. Its been moved out of core PowerShell and is now available on the PSGallery.
£> Find-Module *Script*
Version Name Repository
------- ---- ----------
0.1 nScriptAnalyzerRules PSGallery
1.0.2 PSScriptAnalyzer PSGallery
1.3.1.0 ScriptBrowser PSGallery
1.5.2.0 ScriptCop PSGallery
1.0.4.0 ScriptCS PSGallery
1.0 ScriptTransforms PSGallery
1.0 SQLInvokeScripts PSGallery
You can install it from the gallery
£> Install-Module -Name PSScriptAnalyzer
You are installing the module(s) from an untrusted repository. If you trust this repository, change its
InstallationPolicy value by running the Set-PSRepository cmdlet.
Are you sure you want to install software from 'https://www.powershellgallery.com/api/v2/'?
[Y] Yes [A] Yes to All [N] No [L] No to All [S] Suspend [?] Help (default is "N"): y
By default the gallery isn’t a trusted source so you’ll need to confirm the install. I’d recommend NOT making PSGallery a trusted source. That designation should be reserved for your internal repositories.
The module has 2 cmdlets
£> Get-Command -Module PSScriptAnalyzer
CommandType Name
----------- ----
Cmdlet Get-ScriptAnalyzerRule
Cmdlet Invoke-ScriptAnalyzer
You can view the rules currently available:
£> Get-ScriptAnalyzerRule | Format-Table RuleName, Severity -AutoSize
RuleName Severity
-------- --------
PSAvoidUsingCmdletAliases Warning
PSAvoidDefaultValueSwitchParameter Warning
PSAvoidUsingEmptyCatchBlock Warning
PSAvoidGlobalVars Warning
PSAvoidInvokingEmptyMembers Warning
PSAvoidUsingPositionalParameters Warning
PSReservedCmdletChar Warning
PSReservedParams Warning
PSAvoidShouldContinueWithoutForce Warning
PSAvoidUsingDeprecatedManifestFields Warning
PSProvideDefaultParameterValue Warning
PSAvoidUninitializedVariable Warning
PSAvoidUsingUserNameAndPassWordParams Error
PSAvoidUsingComputerNameHardcoded Error
PSAvoidUsingConvertToSecureStringWithPlainText Error
PSAvoidUsingInternalURLs Information
PSAvoidUsingInvokeExpression Warning
PSAvoidUsingPlainTextForPassword Warning
PSAvoidUsingWMICmdlet Warning
PSAvoidUsingWriteHost Warning
PSUseOutputTypeCorrectly Information
PSMissingModuleManifestField Warning
PSPossibleIncorrectComparisonWithNull Warning
PSProvideCommentHelp Information
PSUseApprovedVerbs Warning
PSUseCmdletCorrectly Warning
PSUseDeclaredVarsMoreThanAssigments Warning
PSUsePSCredentialType Warning
PSShouldProcess Warning
PSUseShouldProcessForStateChangingFunctions Warning
PSUseSingularNouns Warning
PSDSCDscTestsPresent Information
PSDSCDscExamplesPresent Information
PSDSCUseVerboseMessageInDSCResource Information
PSDSCUseIdenticalMandatoryParametersForDSC Error
PSDSCUseIdenticalParametersForDSC Error
PSDSCStandardDSCFunctionsInResource Error
PSDSCReturnCorrectTypesForDSCFunctions Information
You can also get a description of the rule. Its worth reading through the rules to see what is considered best practice by the authors of this module!
This simple script should trigger a few rules 
Write-Host 'getting data'
gwmi Win32_computersystem
£> Invoke-ScriptAnalyzer -Path C:\TestScripts\testsa.ps1 | fl
RuleName : PSAvoidUsingWriteHost
Severity : Warning
Line : 1
Column : 1
Message : File 'testsa.ps1' uses Write-Host. This is not recommended because it may not work in some hosts or there may even be no hosts at all. Use Write-Output instead.
RuleName : PSAvoidUsingPositionalParameters
Severity : Warning
Line : 2
Column : 1
Message : Cmdlet 'gwmi' has positional parameter. Please use named parameters instead of positional parameters when calling a command.
RuleName : PSAvoidUsingPositionalParameters
Severity : Warning
Line : 1
Column : 1
Message : Cmdlet 'Write-Host' has positional parameter. Please use named parameters instead of positional parameters when calling a command.
RuleName : PSAvoidUsingCmdletAliases
Severity : Warning
Line : 2
Column : 1
Message : 'gwmi' is an alias of 'Get-WmiObject'. Alias can introduce possible problems and make scripts hard to maintain. Please consider changing alias to its full content.
Nice simple way to test your code for best practices and avoid some of the major issues that make scripts difficult to read and maintain
Masking output
Published August 8, 2015A question on the forum on how to stop the output from New-Item raises an important point. Many cmdlets produce output when run for example
£> New-Item -Type File -Name test.txt
Directory: C:\Test2
Mode LastWriteTime Length Name
---- ------------- ------ ----
-a---- 08/08/2015 14:14 0 test.txt
There are times when you want to hide that output. The converse situation where you want output from cmdlets that don’t normally produce it can be resolved with the –Passthru parameter where present or by using –verbose.
You have a number of choices when trying to mask output
£> New-Item -Type File -Name test1.txt | Out-Null
£> [void](New-Item -Type File -Name test2.txt)
£> New-Item -Type File -Name test3.txt > $null
£> $nf = New-Item -Type File -Name test4.txt
Any of the above techniques will work. I prefer the first one as I can develop and test the code showing output and then pipe to out-null to mask it
WMF 5 roadmap
Published August 7, 2015With the recent release of Windows 10 a lot of confusion has arisen regarding the position of PowerShell 5.0.
That confusion has been cleared up with a post from the PowerShell team - http://blogs.msdn.com/b/powershell/archive/2015/08/06/windows-management-framework-wmf-5-0-roadmap.aspx