Power Tips

Yesterday we looked at how PowerShell can turn IEEE754 floating point values returned by a sensor into the actual value. This involved reversing the byte order and using the BitConverter class.

If you have received a IEEE754 value in hex format, like 0x3FA8FE3B, the first task is to split the hex value into four bytes. There is a surprisingly easy way to do this: treat the hex value as an IPv4 address. These addresses…

PowerShell is extremely versatile and nowadays often used with IoT and sensors as well. Some return values in IEEE754 float format which typically is a series of four hexadecimal bytes.

Let’s assume a sensor returns a value in the hexadecimal format of 3FA8FE3B and uses IEEE754 formatting. How do you get the real value?

Technically, you have to reverse the byte order, then use the BitConverter to produce a “Single…

In the previous tip we explained how the throw statement can be influenced by $ErrorActionPreference set to “SilentlyContinue”, and that throw will not exit function code properly. Here is again the example we used:

function Copy-Log
{
  "Doing prerequisites"
  "Testing whether target path exists"
  "If target path does not exist, bail out"
  throw "Target path does not exist…

Throw is a PowerShell statement that emits an exception to the caller and then exits the code. At least in theory. In the real world, throw might not exit the code, and the results can be devastating.

To understand the problem, take a look at this demo function:

function Copy-Log
{
  "Doing prerequisites"
  "Testing whether target path exists"
  "If target path does not exist, bail out"

Here’s a special service to users with German language skills – and a challenge to adjust the code for everyone else: the code below uses the RSS feed from a major German news magazine, opens a selection window where you can select one or more articles, and then opens the selected articles in your default browser:

# URL to RSS Feed
$url = 'http://www.spiegel.de/schlagzeilen/index.rss'


$xml = New…

When you view PowerShell scripts in Windows Explorer and have the preview pane open, by default you don’t get a code preview for your script files. The preview pane remains blank.

To enable the preview, simply use the function below:

function Enable-PowerShellFilePreview
{
    [CmdletBinding()]
    param
    (
        [string]
        $Font = 'Courier New',
        
        [int]
        $FontSize = 60

If you want to eliminate completely empty array elements (and do not need to focus on empty properties), here are some approaches with fundamentally different performance:

# create huge array with empty elements
$array = 1,2,3,$null,5,0,3,1,$null,'',3,0,1
$array = $array * 1000

# "traditional" approach (6 sec)
Measure-Command {
    $newArray2 = $array | Where-Object { ![string]::IsNullOrWhiteSpace(

Occasionally you come across lists (arrays) with empty elements. What’s the best way of removing empty elements?

Let’s first focus on a common use case: the code below creates a software inventory by reading the installed software from the registry. The software list is then displayed in a grid view window, and most likely you’ll see elements with empty properties:

$Paths = 'HKCU:\Software\Microsoft…

Let’s assume in an array you want to get rid of all elements that are either empty or null. This is what many would do:

 
PS> 1,2,$null,"test","",9 | Where-Object { $_ -ne '' -and $_ -ne $null }

1
2
test
9

PS>  
 

However, this comparison is dangerous because it also eliminates the value 0:

 
PS> 1,2,0,$null,"test","",0,9 | Where-Object { $_ -ne '' -and $_ -ne $null }

1
2
test…

For reporting and similar use cases, scripts may require the first and last day in a given month. The first day is easy, yet the last day depends on month and year. Here is a simple calculator. Just specify the month and year you need:

[ValidateRange(1,12)][int]$month = 3
$year = 2019
$last = [DateTime]::DaysInMonth($year, $month)
$first = Get-Date -Day 1 -Month $month -Year $year -Hour 0 -Minute 0 -Second 0
$last = 

Whenever you have a true DateTime (and not a string, for example), you have plenty of powerful ways to format. You can get DateTime objects directly:

 
PS> $installDate = (Get-CimInstance -Class Win32_OperatingSystem).InstallDate

PS> $installDate.GetType().FullName
System.DateTime 
 

Or you can convert a string to a DateTime:

 
PS> $psconf = Get-Date -Date '2019-06-04 09:00'

PS> $psconf.GetType().FullName
System…

Ever wondered how old your Windows installation is? A one-liner can tell:

 
PS> (Get-CimInstance -Class Win32_OperatingSystem).InstallDate

Freitag, 8. Juni 2018 18:24:46  
 

Two things are noteworthy: first, we are apparently using a German system. Second, the install date may be much more recent than you think: every new major Windows 10 update actually performs a full reinstall.

If you’d like to change the culture…

Are you tired of OneDrive icons polluting your file explorer tree view? If you don’t use OneDrive, then here are two handy functions that hide and show the OneDrive icons in File Explorer:

function Disable-OneDrive
{
  $regkey1 = 'Registry::HKEY_CLASSES_ROOT\CLSID\{018D5C66-4533-4307-9B53-224DE2ED1FE6}'
  $regkey2 = 'Registry::HKEY_CLASSES_ROOT\Wow6432Node\CLSID\{018D5C66-4533-4307-9B53-224DE2ED1FE6…

PowerShell 5 and later releases come with a cmdlet to automatically add new Windows features, so if you are running a Windows Server and would like to use the Workstation features on it, open a PowerShell with Administrator privileges, and run this line:

Enable-WindowsOptionalFeature -FeatureName DesktopExperience -All -Online -NoRestart 

psconf.eu – PowerShell Conference EU 2019 – June 4-7, Hannover Germany – visit…

XPS is a document format similar to PDF from Microsoft. Although it never really was used in a large scale, it can still be a valuable internal format to print information to a file. To print unattended to XPS files, first you need to set up a new printer that automatically prints to a specific output file:

#requires -RunAsAdministrator

$OutPath = "$env:temp\out.xps"
$PrinterName = "XPSPrinter"
Add…

BOM (Byte Order Mask) is a characteristic byte sequence used in some Unicode encoded text files. If you receive text files with BOM that need to be processed by systems not supporting BOM, here is a way how PowerShell can remove the BOM from such files:

function Remove-BomFromFile ($OldPath, $NewPath)
{
  $Content = Get-Content $OldPath -Raw
  $Utf8NoBomEncoding = New-Object System.Text.UTF8Encoding $False
  [IO.File

In the previous tip we pointed you to a great compilation of PowerShell cheat sheets. Let’s now check out how easily PowerShell can download these sheets for you:

# enable SSL download
$AllProtocols = [System.Net.SecurityProtocolType]'Ssl3,Tls,Tls11,Tls12'
[System.Net.ServicePointManager]::SecurityProtocol = $AllProtocols

# download page
$url = "https://github.com/PrateekKumarSingh/CheatSheets/tree/master…

Here is a great compilation of popular PowerShell cheat sheets, completely free and ready for download:

https://github.com/PrateekKumarSingh/CheatSheets/tree/master/Powershell

psconf.eu – PowerShell Conference EU 2019 – June 4-7, Hannover Germany – visit www.psconf.eu There aren’t too many trainings around for experienced PowerShell scripters where you really still learn something new. But there’s one…

Text files can be stored using different encodings, and to correctly reading them, you must specify the encoding. That’s why most cmdlets dealing with text file reading offer the -Encoding parameter (for example, Get-Content). If you don’t specify the correct encoding, you are likely ending up with messed up special characters and umlauts.

Yet how do you (automatically) determine the encoding a given text…

On Windows 10, when you hold CTRL+SHIFT and then move your mouse wheel, you can easily control the transparency of console window, including the PowerShell console window.

psconf.eu – PowerShell Conference EU 2019 – June 4-7, Hannover Germany – visit www.psconf.eu There aren’t too many trainings around for experienced PowerShell scripters where you really still learn something new. But there’s one place…

Here is a one-liner that retrieves your original Windows product key:

(Get-WmiObject -Class "SoftwareLicensingService").OA3xOriginalProductKey

psconf.eu – PowerShell Conference EU 2019 – June 4-7, Hannover Germany – visit www.psconf.eu There aren’t too many trainings around for experienced PowerShell scripters where you really still learn something new. But there’s one place you don’t want…

In the previous tip we explained how PowerShell can send PDF documents to the default PDF printer. This generic approach is OK for simple scenarios but won’t let you choose a specific printer.

You get more control when you use a specific software because then you can use specific features exposed by that software.

The example below uses Acrobat Reader to print out PDF documents. It shows how you can use the specific…

To automatically print PDF documents, unfortunately you cannot use Out-Printer. Out-Printer can only send pure text documents to a printer.

However, take a look at this line:

# adjust this path to the PDF document of choice
$Path = "c:\docs\document.pdf"

Start-Process -FilePath $Path -Verb Print

Provided you have software installed that can print PDF document, this code sends the document to the associated…

Windows 10 comes with Windows Subsystem for Linux (WSL) feature that you can use to run various Linux distributions. Launch a PowerShell with elevated privileges to enable the WSL:

Enable-WindowsOptionalFeature -FeatureName Microsoft-Windows-Subsystem-Linux -Online  

Next, open the Microsoft Store on Windows 10, and search for “Linux”. Install one of the supported Linux distros (for example, Debian)!

That…

Here is a one-liner that returns the resolved name from the current user’s SID:

([System.Security.Principal.WindowsIdentity]::GetCurrent()).User.Translate( [System.Security.Principal.NTAccount]).Value

You may be arguing it is easier to query the environment variable $env:username for this, which is true. However, converting a SID to name can come handy in many scenarios. For example, if you must know the exact…