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= Cheatsheet PowerShell =

**Summary**: Powershell hints, tips, oneliners and best practices. \\
**Date**: 8 December 2024 \\
{{tag>cheatsheet powershell}}

== Useful links ==

* [[https://poshcode.gitbook.io/powershell-practice-and-style/style-guide/introduction|Best practices and Styling]]
* [[https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_commonparameters|Common parameters]]

== PowerShell Help ==

>Get-Help with -Parameter is a quick way to examine the data type a given parameter expects:
<code powershell>
PS> Get-Help Get-ChildItem -Parameter Path

-Path <String[]>
    Specifies a path to one or more locations. Wildcards are permitted. The default location is the current directory (`.`).

    Required?                    false
    Position?                    0
    Default value                Current directory
    Accept pipeline input?       True (ByPropertyName, ByValue)
    Accept wildcard characters?  false
</code>

== PowerShell History ==

> View history of powershell commands and invoke them using "r #"
<code powershell>
Get-History
<# Output #>
r 1
</code>
\\
> See all saved commands in vscode
<code powershell>
code (Get-PSReadLineOption).HistorySavePath
</code>

== PowerShell If ==

> If statement
<code powershell>
if (($alllogs -eq "True") -AND ($result)){
    Write-Host "Both statements are true"
}elseif (($buildreason -eq "IndividualCI") -or ($buildreason -eq "BatchedCI") -or ($buildreason -eq "PullRequest")){
    Write-Host "At least one of the statements is true"
}else {
    Write-Host "None of the statements is true"
}
</code>

== PowerShell Count ==

> Count number of strings / objects
<code powershell>
# string
$een = "een"
$een.Count
1

# Array
$twee = @("een","twee")
$twee.count
2
</code>
\\
> Length
<code powershell>
# string
$een = "een"
$een.Length
3

# Array
$twee = @("een","twee")
$twee.Length
2
$twee[0].Length
3
</code>
\\
> Measure-Object - Sometimes counting when there is only one item can [[https://stackoverflow.com/questions/36574283/powershell-count-function-not-working-as-expected|fail]], use measure-object instead.
<code powershell>
$een = "een"
($een | Measure-Object).Count
1
$twee = @("een","twee")
($twee | Measure-Object).Count
2
</code>

== PowerShell Dates ==

<code powershell>
# Dates
$timestamp = Get-Date -format "yyyyMMdd-HH.mm" # 20211011-14.27
$readdate = Get-Date -format "d MMM yyyy" # 11 Oct 2021
$weekdate = Get-Date -uformat %V # Week number # 41
$monthdate = Get-Date -format "MMMM-yyyy" # May-2021
</code>
\\
>add or subtract days
<code powershell>
[datetime]$endDate = (Get-Date).AddDays(+90)
[datetime]$endDate = (Get-Date).AddDays(-90)
</code>

== Powershell Error Handling ==

> Error handling [[https://powershellexplained.com/2017-04-10-Powershell-exceptions-everything-you-ever-wanted-to-know/|explained]]

> Try Catch Error Finally with LineNumber for troubleshooting
<code powershell [enable_line_numbers="true"]>
function Get-ScriptLineNumber {
    return $MyInvocation.ScriptLineNumber }
try{
    Write-Host "Do something that you want to catch the error of"
}catch{
    # Catch the error
    Write-Host "Full Error: $_"
    # Or error out after all
    Throw "Failed on: $actionname; Status: Failed; Line: $(Get-ScriptLineNumber); Error: $($_.Exception.Message)"
}finally {
    <#Do this after the try block regardless of whether an exception occurred or not#>
    # For example, clean up remote ps sessions
}
</code>
\\
> Exception.options
<code powershell>
try{
    # Do something that you want to catch the error of
    Get-ChildItem \\prox-hyperv -ErrorAction Stop

    # [System.Net.DNS]::GetHostByName("server99")

    # Connect-AzAccount
    # Get-AzResourceGroup -Name "exampleGroup" -ErrorAction Stop
}catch [System.Management.Automation.ItemNotFoundException] {
    Write-Host "Cannot find item."
    Write-Host -NoNewLine "Exception Message        : "
    Write-Host -Foreground Red -Background Black "$($_.Exception.Message)"
}catch{
    # Catch the error
    Write-Host -Foreground Red -Background Black "Error found. Please try again, or if the error persists, contact support for evaluation. Please provide the following diagnostics:"
    Write-Host -NoNewLine "Exception Message        : "
    Write-Host -Foreground Red -Background Black "$($_.Exception.Message)"

    # Exceptions can contain inner exceptions. This is often the case when the code you are calling catches an exception and throws a different exception. They will place the original exception inside the new exception.
    Write-Host -NoNewLine "Inner Exception Message  : "
    Write-Host -Foreground Red -Background Black "$($_.Exception.InnerException.Message)"

    # The FullyQualifiedErrorId is the .Message property of the exception object along with the the fully-qualified name of the class where the exception originated.
    Write-Host -NoNewLine "Fully Qualified Error Id : "
    Write-Host -Foreground Red -Background Black "$($_.FullyQualifiedErrorId)"

    # Output provides the error type you need to catch this specific error type
    Write-Host -NoNewLine "Exception type           : "
    Write-Host -Foreground Red -Background Black "$($_.Exception.GetType().fullname)"

    # Shows the  powershell command. Does not work for .Net exceptions
    Write-Host -NoNewLine "Command                  : "
    Write-Host -Foreground Red -Background Black "$($_.InvocationInfo.MyCommand)"

    # Position of the error in the scriptblock or file
    Write-Host -NoNewLine "Position                 : "
    Write-Host -Foreground Red -Background Black "At line: $($_.InvocationInfo.ScriptLineNumber) char:$($_.InvocationInfo.OffsetInLine)"

    # Shows the faulty line. Also works for .Net exceptions
    Write-Host -NoNewLine "Full line                : "
    Write-Host -Foreground Red -Background Black "$($_.InvocationInfo.Line)"

    # Shows the full error. Useful for troubleshooting. Provides output so use careful when returning output.
    Write-Host "Full Error:"
    Get-Error

    # Shows the full error for AZ cmdlets. Useful for troubleshooting. Provides output so use careful when returning output. Usually also works with non AZ cmdlets.
    Write-Host "Full Azure Error:"
    Resolve-AzError -Last
}finally {
    #Do this after the try block regardless of whether an exception occurred or not. For example, clean up remote ps sessions, clear variables or cleanup files.
}

</code>
== PowerShell Input and Output ==

> Enable logging of script
<code powershell [enable_line_numbers="true"]>
### Script Variables ###
$scriptname = [System.IO.Path]::GetFilenameWithoutExtension($MyInvocation.MyCommand.Path.ToString())
$scriptlocation = Split-Path $myinvocation.mycommand.path
$date = (Get-Date).ToString('yyyyMMdd-HHmm')

### Start transcript for full logging capabilities ###
start-transcript -path "$scriptlocation\$scriptname-$date-logtranscript.txt"

### Stop transcript
Stop-transcript
</code>
\\
> Script output and Write-Host options
<code powershell [enable_line_numbers="true"]>
# Inside a function use return or write-output
return "value"
Write-Output $value
# Output an object without adding it to the function output
Write-Host "color" -ForegroundColor Red  -BackgroundColor green -noNewLine
$object | Out-Host
</code>
\\
> Input password
<code powershell>
$password = Read-Host "Enter password" -asSecureString
</code>
\\
> Use padright to fill a line with one symbol
<code powershell>
Write-Host ''.PadRight(78, '=')
# Or with a variable
$wide = 32
Write-Host ''.PadRight($wide, '=')
</code>
\\

== Preference Variables ==
[[https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_preference_variables|About Preference Variables]]

> Verbose Preference
<code powershell>
# Default
$VerbosePreference = 'SilentlyContinue'
# Override: -Verbose

# Verbose output
$VerbosePreference = 'Continue'
# Override: -Verbose:$false
</code>
\\
> Debug Preference
<code powershell>
# Default
$DebugPreference = 'SilentlyContinue'
# Debug output
$DebugPreference = 'Continue'
</code>
\\
> Whatif Preference
<code powershell>
# Default
$WhatIfPreference = $false
# Override: -WhatIf

# When WhatIf is enabled, the cmdlet reports the expected effect of the command, but doesn't execute the command.
$WhatIfPreference = $true
# Override: -WhatIf:$false
</code>
== PowerShell Variables ==

> Set system (environment) variable
<code powershell>
$env:var="value"
</code>
\\
> Get all system (environment) variables, sorted by name
<code powershell>
get-childitem -path env:* | Sort Name
</code>
\\
> Variables in function
> Declare a variable with script scope to use it in a function
<code powershell>
$script:orgUrl = "https://dev.azure.com/getshiftingcom"
$script:apiversion = "api-version=6.0"
function SetBuildTag {
  # Load Azure DevOps API settings
  AzureDevOpsAPISettings
  foreach ($tag in $tags){
      $tagurl = "$orgUrl/$env:System_Teamproject/_apis/build/builds/$env:BUILD_BUILDID/tags/$($tag)?$apiversion"
  }
}
</code>
\\
> set variable with a dash/hyphen
<code powershell>
New-Variable -Name "MODULE-SiteName" -Value "Incomingapi"
</code>
\\
> set system variable with a dash/hyphen
<code powershell>
[Environment]::SetEnvironmentVariable('MODULE-SiteName','Incomingapi')
</code>
\\
> Set system variables with a dash/hyphen
<code powershell>
${env:test-app_user} = "svc-test-dev"
$user = ${env:test-app_user}
</code>
\\
> Check if a variable is null or empty
<code powershell>
if ([string]::IsNullOrEmpty($VarToCheck)){
  do something
}
</code>
== Remote PowerShell ==

> Set variables
<code powershell [enable_line_numbers="true"]>
$AdminCredentials = Get-Credential
$remotePort = 5986
$pso = New-PSSessionOption -SkipCACheck -SkipCNCheck -SkipRevocationCheck
$Culture = "en-US"
$pso.Culture = $Culture
$pso.UICulture = $Culture
$sessionParams = @{}
$sessionParams.Add('UseSSL', $true)
$sessionParams.Add('Port', $remotePort)
$sessionParams.Add('Credential', $AdminCredentials)
</code>
\\
> Start session to restart computer
<code powershell>
$session = New-PSSession -ComputerName webserverdmz.domain -EnableNetworkAccess -SessionOption $pso @sessionParams
Invoke-Command -Session $session -ScriptBlock {Restart-Computer}
Remove-PSSession $session
</code>

== PowerShell Function Template ==

> See [[https://poshcode.gitbook.io/powershell-practice-and-style/style-guide/function-structure|here]] for guidelines.

<code powershell>
function Use-AzureDevOpsApi{ #Use Get-Verb for a list of approved verbs
    <#
    .SYNOPSIS
        Short description

    .DESCRIPTION
        Long description

    .PARAMETER Pat
        Explain the parameter Pat. Repeat for additional parameters.

    .OUTPUTS
        Explain the powershell output, if any

    .EXAMPLE
        Pipeline example:
        - task: PowerShell@2
          displayName: "Use Default SystemAccessToken"
          env:
            SYSTEM_ACCESSTOKEN: $(System.AccessToken)
          inputs:
            pwsh: true
            targetType: 'inline'
            script: |
                # Load Azure DevOps API settings
                Use-AzureDevOpsApi

        Script example:
        Use-AzureDevOpsApi -Pat $Pat

    .LINK
        System access token: https://docs.microsoft.com/en-us/azure/devops/pipelines/build/variables?view=azure-devops&tabs=yaml#systemaccesstoken

    .NOTES
        Author : Sjoerd Hooft
        Version: 2022-08-03

    #>
    [CmdletBinding()]
    param (
        [Parameter()]
        [ValidateLength(52,52)] # See for more parameter validation https://poshcode.gitbook.io/powershell-practice-and-style/style-guide/function-structure
        [ValidateSet("dev", "tst", "acc")]
        [string]
        $Pat
    )

    begin {
        Write-Host "##[section]Function: $($MyInvocation.MyCommand)"
        Write-Verbose "Input: $($PSBoundParameters | Out-String)"

        # Set Verbose switch based on PSBoundParameters
        $CmdLetOutput = @{Verbose = $($PSBoundParameters.Verbose)}
        # Collect information
    }

    process {
        # Do stuff
    }

    end {
        # Cleanup
    }
}
</code>

== PowerShell Function Validates ==

* Not null or empty: {{{[ValidateNotNullOrEmpty()]}}}
* Latest or YYYY-MM: {{{[ValidatePattern("latest|20\d{2}[-]\d{2}")]}}}
* Email: {{{[ValidatePattern('(.+@getshifting\.com)$')]}}}
* Specific server name: {{{[ValidatePattern("web(dev|tst|acc)dmz0[12]")]}}}
* Environment: {{{[ValidateSet("dev", "tst", "acc", "prd")]}}}
* Number between: {{{[ValidateRange(8,100)]}}}
* Length range: {{{[ValidateLength(8,12)]}}}
* Length exactly: {{{[ValidateLength(8,8)]}}}

== PowerShell Modules ==

> Check Azure powershell module depending on PS version
<code powershell [enable_line_numbers="true"]>
Write-Host "Check required PowerShell Modules `n"
# The "new" PS module for Azure requires PowerShell 7
if ($($PSVersionTable.PSVersion).Major -eq 7){
  if (Get-Module -ListAvailable -Name AZ) {
    Write-Host "PowerShell module Azure exists"
  } else {
    Write-Host "PowerShell module Azure does not exist. Start installation. "
    Install-Module -Name Az -Scope CurrentUser -Repository PSGallery -Force
  }
}else{
    Throw "Powershell needs to be version 7"
}
</code>
\\
> PowerShell DNS Module
<code powershell>
if (Get-Module -ListAvailable -Name DnsServer) {
    Write-Host "PowerShell module DnsServer exists"
} else {
    Write-Host "Module DNSServer does not exist. Starting installation"
    Import-Module ServerManager
    Add-WindowsFeature -Name "RSAT-DNS-Server"
}
</code>
\\
> PowerShell AD Module
<code powershell>
# Because ActiveDirectory is a 5.1 module you need to add -All
if (Get-Module -ListAvailable -All -Name ActiveDirectory) {
    Write-Host "PowerShell module ActiveDirectory exists"
} else {
    Write-Host "Module ActiveDirectory does not exist. Starting installation"
    Import-Module ServerManager
    Add-WindowsFeature -Name "RSAT-AD-PowerShell" –IncludeAllSubFeature
}
</code>
\\
> PowerShell Pester module, remove shipped version and install latest version (Needs PS 7)
<code powershell [enable_line_numbers="true"]>
if (Get-Module -ListAvailable -Name Pester) {
  # Check for version 3.4 and if available remove it
  Get-Module -ListAvailable -Name Pester
  if (((((Get-Module -ListAvailable -Name Pester).Version).Major) -eq 3) -AND ((((Get-Module -ListAvailable -Name Pester).Version).Minor) -eq 4)) {
    Write-Host "PowerShell Module Pester is version 3.4 which is shipped along with Win10/Windows 2016. Start removal:"
    $module = "C:\Program Files\WindowsPowerShell\Modules\Pester"
    takeown /F $module /A /R
    icacls $module /reset
    icacls $module /grant "*S-1-5-32-544:F" /inheritance:d /T
    Remove-Item -Path $module -Recurse -Force -Confirm:$false
  }
  # Verifieer of Pester al aanwezig met minimaal versie 5
  if ((((Get-Module -ListAvailable -Name Pester).Version).Major) -ne 5) {
    Write-Host "PowerShell module Pester is not up to date"
    Install-Module -Name Pester -Force -Scope CurrentUser
  }else{
    Write-Host "PowerShell Module Pester is available with minimal version of 5:"
    Get-Module -ListAvailable -Name Pester
  }
} else {
  Write-Host "PowerShell module Pester does not exist. Start installation. "
  Install-Module -Name Pester -Force -Scope CurrentUser
}
</code>
\\
> IIS Administration Module, install extra version, see the version and the available commandlets. Note that this needs to be done in PowerShell 5 Administrative Shell
<code powershell>
Install-Module -Name IISAdministration -Scope AllUsers -Force #Installs latest version next to it (1.1.0.0)
Import-Module IISAdministration -RequiredVersion 1.1.0.0
$mod = Get-Module -Name IISAdministration
$mod.Version
$mod.ExportedCmdlets | Format-Table
</code>
\\
>Import PS Module
<code powershell>
Import-Module Pester
</code>
\\
> Get commands within a module
<code powershell>
Get-Command -module Pester
</code>
\\
> Get module for a command
<code powershell>
Get-Command Get-Service
</code>
\\
> Remove / Unload a PowerShell module
<code powershell>
Remove-Module Pester
</code>

== PowerShell Requires ==

<code powershell>
#Requires -Version 7.0
#Requires -PSEdition Core
# Requires for modules is slow because it also imports them
# Requires does not work for non-PS Core modules like DNS and ActiveDirectory
#Requires -Modules @{ ModuleName="Pester"; ModuleVersion="5.0" }
#Requires -Modules Az
#Requires -Modules AzureRmStorageTable
</code>

== PowerShell ForEach ==

> With custom PS Object and export to csv
<code powershell [enable_line_numbers="true"]>
$myCol = @()
foreach ($vm in (get-vmhost esxprd101.intranet | get-vm )){
  $VMInfo = "" | Select-Object VMName,VMHostName,NICCount
  $VMInfo.VMName = $vmview.Name
  $VMInfo.VMHostName = $vmview.Guest.HostName
  $VMInfo.NICCount = $vmview.Guest.Net.Count
  $myCol += $VMInfo
}
$myCol |Export-csv -NoTypeInformation $csvfile
</code>

== PowerShell Comparison ==

> Overview
<code powershell>
# logical and comparison
# -and, -or, -not , ! : Connect expressions
# -eq, -ne : Equal, not equal
# -gt / -lt, -ge / -le : Greater/less than, greater or equal / less or equal
# -replace
# -match / -notmatch : Regular expression match
# -like / -notlike : wilcard matching
# -contains / -notcontains : check for value in array: $array -contains $value
# -in / -notin : reverse syntax from contains: $value in $array
</code>

== PowerShell Location ==

> Change directory (alias cd)
<code powershell>
Set-Location c:\
</code>
\\
> Change directory and back
<code powershell>
PS C:\Users\sjoer> Push-Location c:\
PS C:\> Pop-Location
PS C:\Users\sjoer>
</code>

== Azure PowerShell ==

> **NOTE: Module AZ only works in PowerShell 7**
\\
> TLS version
<code powershell>
# Set TLS version to use TLS 1.2
[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
</code>

=== Login to Azure ===

> Login and context
<code powershell>
Connect-AzAccount
Get-AzContext -ListAvailable
Set-AzContext -Name $dtapEnvironment -Subscription $azureSubscriptionName
</code>
\\
>Get TenantId
<code powershell>
$tenantId = (Get-AzContext).Tenant.Id
</code>

=== KeyVault ===

> Get secret from KeyVault
<code powershell>
$adadminpass = (Get-AzKeyVaultSecret -VaultName kv-operations-global -Name "adAdminPass").SecretValue
</code>
\\
> Set secret to KeyVault
<code powershell>
$userpasswordsecure = ConvertTo-SecureString -String $userpassword -AsPlainText -Force
Set-AzKeyVaultSecret -VaultName kv-operations-global -Name $username -SecretValue $userpasswordsecure
</code>

=== Resourcegroup Creation Time ===

<code powershell>
((Invoke-AzRestMethod -Path "/subscriptions/$subId/resourcegroups?api-version=2020-06-01&`$expand=createdTime" -Method GET).Content | ConvertFrom-Json).value | Select-Object name,createdTime
</code>