Even More PowerShell Fun

The Story

It’s another day, and we all know what that means… yes, another blog post, and even more PowerShell! Can you feel all the power!?!?!

This time it came down to the storage size of my Exchange servers C:\ which turns out to be due to Logs. Logs are great, and best practice is to only clear them if you have a backup copy. Often is the case that logs can be truncated after a backup via VSS by many backup solutions however in my case I could and probably should get that validated with Veeam (as I can’t seem to get that working ‘out of the box’) at the moment. So instead I wanted to know what was “usually” done server side even if someone was not implementing a backup solution.

Source: https://social.technet.microsoft.com/wiki/contents/articles/31117.exchange-201320162019-logging-clear-out-the-log-files.aspx

Neat, but the script is just alright, good for them doing what they want and that’s running it as a scheduled task. Not my goal, but a great source and starting point… let’s have some fun and give this script some roids, much like my last one… I’ll give this a home on GitHub.

Things learned…

  1. Working with the Registry
  2. Determining if Elevated (This is great and I may have a solution to the conundrum in my previous PowerShell post)
  3. Getting a Number, and validating it
  4. Validating Objects by Type
  5. Getting Folder Sizes

Check out my script for all the fun coding bits. I’m a bit tired now as it’s getting late so not much blogging, all more coding. 🙂

ErrorAction Stop Not Stopping Script

Quick Educational note (Source)

$ETLLogKey2 = 'HKLM:\SOFTWARE\Microsoft\Search Foundation for Exchange\Diagnostics'
try{Get-ItemProperty -Path $ETLLogKey2 -ErrorAction Stop}
catch{Write-Host "No Key"}
Write-Host "This should not hit"

Produces:

Well poop… The catch block was triggered but the script did not stop…

Oddly, changing to Throw, which is ugly does make the script stop…

$ETLLogKey2 = 'HKLM:\SOFTWARE\Microsoft\Search Foundation for Exchange\Diagnostics'
try{Get-ItemProperty -Path $ETLLogKey2 -ErrorAction Stop}
catch{throw "No Key"}
Write-Host "This should not hit"

Nice it worked this time, but it’s ugly…

Write-Error is just as ugly, but doesn’t stop the script?

$ETLLogKey2 = 'HKLM:\SOFTWARE\Microsoft\Search Foundation for Exchange\Diagnostics'
try{Get-ItemProperty -Path $ETLLogKey2 -ErrorAction Stop}
catch{Write-Error "No Key"}
Write-Host "This should not hit"

Produces:

Yet if I follow Sages answer in the source, and do a script variable for the stop action it then works???!?!

$ErrorActionPreference = [System.Management.Automation.ActionPreference]::Stop
$ETLLogKey2 = 'HKLM:\SOFTWARE\Microsoft\Search Foundation for Exchange\Diagnostics'
try{Get-ItemProperty -Path $ETLLogKey2}
catch{Write-Error "No Key"}
Write-Host "This should not hit"

Those are really weird results, but all still ugly…  so it seems even though -ErrorAction Stop causes a non-terminating error to be treated as a terminating error, but depending on what you do in the catch block determines if there’s a break/exit event being done. In my case to have things look nice and actually stop the script I have to do the follow.

$ETLLogKey2 = 'HKLM:\SOFTWARE\Microsoft\Search Foundation for Exchange\Diagnostics'
try{Get-ItemProperty -Path $ETLLogKey2 -ErrorAction Stop}
catch{Write-host "No Key";break}
Write-Host "This should not hit"

Which finally produced the output I wanted. (I could have also used exit in place of break)

Finally!

Validating URLs:

Source: 

Good but broken due to the match on the scheme extension:

function isURI($address) {
	($address -as [System.URI]).AbsoluteURI -ne $null
}

function isURIWeb($address) {
	$uri = $address -as [System.URI]
	$uri.AbsoluteURI -ne $null -and $uri.Scheme -match '[http|https]'
}


isURI('http://www.powershell.com')
isURI('test')
isURI($null)
isURI('zzz://zumsel.zum')

"-" * 50

isURIWeb('http://www.powershell.com')
isURIWeb('test')
isURIWeb($null)
isURIWeb('zzz://zumsel.zum')
isURIWeb('hp:') #Return True

 

Better results with:

function isURI($address) {
($address -as [System.URI]).AbsoluteURI -ne $null
}

function isURIWeb($address) {
$uri = $address -as [System.URI]
$uri.AbsoluteURI -ne $null -and $uri.Scheme -match "http|https"
}


isURI('http://www.powershell.com')
isURI('test')
isURI($null)
isURI('zzz://zumsel.zum')

"-" * 50

isURIWeb('http://www.powershell.com')
isURIWeb('test')
isURIWeb($null)
isURIWeb('zzz://zumsel.zum')
isURIWeb('hp:') #Return True

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