Prerequisites 

This is a quick fun little HOWTO.  The was an article on CollegeHumor today that looked like this:

01010100 01101000 01100101 00100000 01110010 01101111 01100010 01101111 01110100 01110011 00100000 01100001 01110010 01100101 00100000 01100001 01101101 01101111 01101110 01100111 00100000 01110101 01110011 00100000 01100001 01101110 01100100 00100000 01110111 01100101 00100000 01100001 01110010 01100101 00100000 01100001 01101100 01101100 00100000 01101001 01101110 00100000 01100100 01100001 01101110 01100111 01100101 01110010 00101110 00100000 01001000 01100101 01101100 01110000 00100000 01110101 01110011 00101100 00100000 01000111 01101111 01100100 00101110

I was of course curious what the message above actually said so I wondered how quickly I could figure that out with PowerShell.  The answer?  Pretty gosh darn quick.

((gc c:\temp\binary.txt) -split " " | % { [char]([convert]::ToInt32("$_",2)) }) -join ""

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This HOWTO covers a real world example of how to use Convert-FromString which was introduced in PowerShell 5.  As a reminder, this is the powerful new cmdlet that allows you to parse any kind of text data and convert the resulting data into structured PowerShell objects by defining “templates” for how the data is laid out and what information you want to extract.

The largest mall in my city includes literally hundreds of stores. I needed to shop for a particular kind of thing and wanted to know what stores I might want to check out.  I started by visiting the website for the mall.  This ended up giving me output that looked like this:

It’s not bad certainly but I would like to apply some filters to the dataset.  Now in reality, I could have certainly figured out what I wanted from this website but I realized this would be a great opportunity to see if I could make the ConvertFrom-String and FlashExtract do something useful.  Could I make a PowerShell object out of this data?

The first thing I did was download the webpage in PowerShell using the Invoke-WebRequest cmdlet.  Powershell includes a “parseddata” object that tries to break down any webpage into its component parts and return the results as nested objects.  I looked at the output and discovered that all of the data I was interested in was stored in parseddata.documentElement.outertext.  This gave me the following results:

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PowerShell 5.0 introduces a wonderful new cmdlet called ConvertFrom-String.  Don’t let the simple name deceive you though.  There is some exceptionally complex math running behind the scenes here to do some truly wonderful things.
In fact, the code that gets executed inside this function is based upon the "FlashExtract" project completed by Microsoft Research.  How much math? Well here is a portion of the algorithm that was published in their whitepaper.

Source: http://research.microsoft.com/en-us/um/people/sumitg/pubs/pldi14-flashextract.pdf

The idea here is to give us as administrators the ability to take some existing complex text data, intelligently analyze it and convert it into native PowerShell objects. 
Technically we can already do this today using regular expressions.  But coming up with the right combination of letters and characters to produce the intended results is no easy task.  At least until now.
The idea here is that instead of trying to micro manage exactly character-by-character how you want to extract the data to get to the content you want, you instead simply ‘tell’ PowerShell want you want.
Specifically, you pass the ConvertFrom-String function a marked up template of the data that indicates which data is important.

It’s hard to understand in writing but will make a lot more sense once you see it in action.  This is also when the "ah ha" moment comes and you realize the power this new cmdlet offers.

For our example, we’re going to take a look at the c:\windows\windowsupdate.log.  This is a plain text log file that contains several columns:

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I recently found myself on a long bus ride with my laptop and no Internet connection.  I decided to create a PowerShell puzzle for myself to keep me busy until I reached my destination.  It ended up being kind of interesting so I wanted to share my puzzle and the solution with here.

Challenge

PowerShell has the concept of “Get-*” cmdlets where these will only retrieve information but will never change anything.  This makes Get commands safe to run, even if you don’t know what they do.   PowerShell ships with hundreds of Get cmdlets.  It would be great to know what kind of information each one provided.  To do that I’d need to run every Get command.  That’s simple enough but is complicated by the fact  that most Get- cmdlets come with multiple ‘parameter sets’ and many are configured with mandatory parameters.  This means that if we blindly run each command we’ll end up with a bunch of errors and prompts for user input.

So what we need to do is figure out which of the Get- commands can be run without passing any parameters.  We then also want to exclude commands that run properly but don’t return any data by default.

Solution

Check out the script below.  It will scan the system for every Get- command and then will figure out which ones can be executed directly without parameters and will actually return data.  It then runs all of those and returns the first 5 objects so you can get a feel for what kind of data is returned.  It will then display a report showing how many cmdlets met each criteria.  On my system for example we can see that 143 commands can be executed and return something useful just by typing the name of the command and hitting enter.

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