Powershell Notes - Advanced Automated Administration Class

These are my notes from the Global Knowledge “Advanced Automated Administration with Powershell” class. Class ran from 2019-06-03 to 2019-06-05.

Advanced Functions and Parameter blocks

• Add [CmdletBinding()] to the head of the function or script.
  Parameter block example:

  Param(
    $ParamOne, #No type or conditions
    [string]$ParamTwo, # parameter expects a string
    [string]$ParamThree = "DefaultValue", # Parameter expects a string, and defaults to "DefaultValue" if no value is provided.
    [Parameter(Mandatory=$true)]
    [string]$ParamFour, # Sets parameter to mandatory.  $True is not required as adding Mandatory assumes true.
  )
  

• [string[]] allows multiple string inputs and requires logic in script to handle; ex: multiple computer names.
• [ValidateCount(start,end)] sets a min and max number of inputs to a parameter.
• [ValidateSet()] Validates only items in the list can be used and are available via tab completion.
• [ValidateScript({True or False script block})] Validate a script block, which evaluates to True or False.
• Add ```ValueFromPipeLine=$true`` to parameter allows accepting a value from the pipeline for a specific paramater.
• Add ValueFromPipelineByPropertyName=$true allows using a property name from the pipeline.
• Both ValueFromPipeLine and ValueFromPipelineByPropertyName can be used on a single parameter.
• Add SupportsShouldProcess=$True to Cmdletbinding() to enable -whatif parameter.
• Add ConfirmImpact="level" to CmdletBinding() enables -confirm.
• ConfirmImpact Levels are “High”, “Medium”, “Low”.
  Example:

    [ValidateScript({
        If(Test-Path(Split-Path $_)){
            $True
        }
        else {
            Throw "Could not find $_"
            }
    })]
  

  
  
  

  Script Modules

• Modules end in .psm1 and are only renamed ps1 files.
• PSModulePath contains the paths to script modules.
• Module name and the directory name must match if not using a module manifest.

    Import-Module ModuleName.psm1 # Import Module
    Remove-Module ModuleName # Remove Module
    dir function: # List install modules
    Get-command # List all available commands
  

  
  
  

  Module Manifest

  Example: New-ModuleManifest -Path Path\To\File.psd1 -RootModule FileName.psm1 # Generate a Module Manifest

• Recommended to use module manifest for more fine grained control over the module.
• In the manifest, ```FunctionToExport`` change be changed to limit the functions exposed to users. The other internal functions would still be available for the exposed functions to use.
• Validate a module manifest with Test-ModuleManifest
  
  

  General Info

• Backtick (`) without a trailing space breaks a command to the next line.
• Multiple function parameters can be broken onto separate lines with a backtick without a trailing space.

• The best place to break multiple pipes is right after the pipe (

  ) symbol and does not require a backtick.

• ”.” references the localhost.
• Works for most Powershell commands, but a few it won’t work with.
• It would not display the name of the local computer. If the computer name needs to be display, $env:COMPUTERNAME should be used instead.
  
  

  Positional Parameters

• Follow the order of the parameters defined in the function or script.
• Rearranging the order of the parameters changes the order.
  
  

  WMI Examples

• Select all Win32_LogicalDisk properties from local computer: Get-WmiObject Win32_LogicalDisk
• Select all logical disks from computer Alpha: Get-WmiObject Win32_LogicalDisk -ComputerName Alpha
• Select Logical disks from Alpha with drive type 3: Get-WmiObject Win32_LogicalDisk -ComputerName Alpha | Where-Object { $_.DriveType -eq 3}
  
  

  Where-Object

  There are two basic formats:

• Simple: Where-Object DriveType -eq 3
• Advanced: Where-Object { $_.DriveType -eq 3}
  The advanced format allows more complex selection critiera including logical AND/OR, while the simple syntax does not support more than a single condition.
  
  

  Comments

• The .Parameter does not have to be used in the comment based help. The parameters for a function can be directly documented, instead of using .Parameter. This can simply documenting and prevent missed .Parameter comments.
  
  

  .Net and Powershell

  [math]::Abs(number) #ABS of a number
  [math]::Sin(number) #SIn of a number
  [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms") # Load Windows forms
  [SystemWindows.Form.MessageBox]::Show("Text") # Display a Windows forms message box
  [System.Environment]::MachineName # Get computer name
  [System.Environment]::OsVersion # Get OS version
  [System.Diagnosics.Process]::GetProcesses() # Get running processes
  [System.Diagnosics.Process]::GetCurrentProcess() # Get process info from current shell
  # Speech Synth
  Add-Type -AssemblyName Speech.Synthesis
  $speech = New-Object System.Synthesis.SpeechSynthesizer
  $speech.Speak("Hello World")
  

  
  

  Debugging

  Write-Verbose

• Write-versobse can be used instead of Write-host.
• Enabled via [CmdletBinding()].
• Only would activate when using the -verbose flag.
  
  Write-Debug
• Enabled via [CmdletBinding()]
• Activated with -Debug
• Stops script execution when triggered.
  
  Breakpoints
• Breakpoints can be set on a line number, on a variable, or on a command.
• Variable breakpoints will trigger every time the variable is used.
• Ex: Set-PSBreakPoint -Variable VariableName -Mode ReadWrite -Script ScriptName