Monthly Archives: September 2017

BEGIN	END	SPEAKER	TITLE
09:15	10:30	Mark van de Waarsenburg	Powershell basics
10:40	11:25	Erik Heeres	Powershell Remoting
11:30	12:15	Jaap Brasser [MVP]	Manage your infrastructure with PowerShell
13:15	14:00	Robert Prust	Improving your scripts
14:00	14:45	Ralph Eckhard	Powershell for Office 365 Administrators
15:20	16:05	Jeff Wouters [MVP]	Tips and tricks
16:10	16:45	DuPSUG Speakers	Ask us (almost) anything

2 Replies

As I have been speaking at a number of events recently I also have been updating my GitHub Events repository. Usually I include a markdown file with a short description, my demos and my slides. I had been uploading my files as .pptx and I noticed that the repository edged over 100 MB. This prompted me into reconsidering this approach, I felt I needed to address the following:

Use the most compatible format available, presentations should be viewable on any device
Fonts should be correctly represented
File size should be minimal

In an effort to more efficiently use the space I have available and to use a more compatible format I decided to convert my presentations to .pdf.

Because I do not like doing stuff manually I decided to use PowerShell in combination with a bit of bash scripting to get my repository updated. First lets take a look what kind of data we are dealing with:

1 2	Get-ChildItem C:\git\Events -File -Filter *pptx -Recurse \| Select-Object -Property FullName

In total 29 presentations uploaded in .pptx format, if I would have to convert these by hand it would take about 30 minutes. Taking a look at what is possible with the PowerPoint.Application Com-Object took about 5 minutes and an additional 5 to put together the following script:

Get-ChildItem C:\git\Events -File -Filter *pptx -Recurse |
ForEach-Object -Begin {
    $null = Add-Type -AssemblyName Microsoft.Office.Interop.PowerPoint
    $SaveOption = [Microsoft.Office.Interop.PowerPoint.PpSaveAsFileType]::ppSaveAsPDF
    $PowerPoint = New-Object -ComObject "PowerPoint.Application"
} -Process {
    $Presentation = $PowerPoint.Presentations.Open($_.FullName)
    $PdfNewName  = $_.FullName -replace '\.pptx$','.pdf'
    $Presentation.SaveAs($PdfNewName,$SaveOption)
    $Presentation.Close()
} -End {
    $PowerPoint.Quit()
    Stop-Process -Name POWERPNT -Force
}

This script will recursively look for all .pptx files in the Events repository and the run the following code:

In the begin block load the PowerPoint Com-Object and the required type for storing files as .pdf
For each presentation, open the presentation, generate a new name and convert it to .pdf
Finally at the end close the PowerPoint application and afterwards using Stop-Process to close the window, note that if you had any other PowerPoint windows open they will also be closed.

Now I have both the .pdf and the .pptx stored in the folder, let’s take a look what the difference in file size is:

foreach ($Extension in ('pptx','pdf')) {
    Get-ChildItem C:\git\Events -File -Filter "*$Extension" -Recurse |
    Measure-Object -Property Length -Sum | ForEach-Object {
        [pscustomobject]@{
            'SizeinMB'  = [math]::Round($_.Sum/1MB,2)
            'Extension' = $Extension
        }
    }
}

A nice decrease in size and a format that is more suitable for sharing, this is looking good. After verifying that the .pdf files are looking good we can remove the .pptx files with the following code:

1 2	Get-ChildItem C:\git\Events -File -Filter *pptx -Recurse \| Remove-Item -Force

The last step is to commit everything to GitHub and make it available to everyone. I found a nice Stack Overflow thread that explained how to mass remove files:

Removing multiple files from a Git repo that have already been deleted from disk

Which left me with the following commands to run to commit everything to the repository using bash:

git ls-files --deleted -z | xargs -0 git rm 
git add *
git commit -m "Removed pesky pptx and added glorious pdf"
git push origin master

And to view the result here is what is looks like on GitHub now and the commit:

GitHub – JaapBrasser – Events – Commits

Let me know what you think, is .pdf a more useful format over .pptx to share presentations or would you rather see it the other way around?

Decipher obfuscated URLs with PowerShell

4 Replies

I recently received a message on Skype from a friend I had not talked to for a while, I was happy to see it was spam. Not because it was spam, but because it was using an encoded Url. After taking a quick look at the structure I thought, this is definitely something I can decode.

To me this looked like hexadecimal code, and I quickly threw together a PowerShell one-liners to decode to decode this, note that I skip the first six character because:

1
2
3

-join [char[]](
'%6A%61%61%70%62%72%61%73%73%65%72%2E%63%6F%6D' -split '%' |
Where-Object {$_} | ForEach-Object {[Convert]::ToInt32($_,16)})

This provides us with the following output:

jaapbrasser.com

Because this is a little bit hard to read, let’s break it up into chunks:

$Split      = '%6A%61%61%70%62%72%61%73%73%65%72%2E%63%6F%6D' -split '%'
$Split      = $Split | Where-Object {$_}
$Integers   = $Split | ForEach-Object {[Convert]::ToInt32($_,16)})
$Characters = [char[]]$Integers
-join $Characters

So let’s go line-by-line through what the code does:

Split the code on the %-character
Skip the first entry, because we split on %, the first result will be empty and can cause errors later
Convert the hexadecimal number to integers using the Convert type accelerator
Convert the integers to Char by strong typing them to a Char array
Use the join operator to turn it into a string

So now that we have this complete, we no longer have to guess where the encoded link is going to lead us. In my case, the link of my friend happened to take me a Russian website trying to get me involved in binary option trading:

For more information about percent encoding as a concept, have a look at the Wikipedia page over here:

Wikipedia – Percent-Encoding

I have created a function for to be able to perform this this conversion in the future, I made it available on GitHub, TechNet Gallery and the PowerShell Gallery: