Articles from October 2013 on PowerShell.org - Welcome Automaters!

PowerShell "Scripting and Toolmaking" Classroom Training Course Now Available to Microsoft Training Centers

Mon, 28 Oct 2013 17:11:03 +0000

Attention Microsoft training centers! Microsoft’s Courseware Marketplace now offers course 55039AC, “Windows PowerShell Scripting and Toolmaking.” Designed as a 5-day course, it’s a spiritual “Part 2” to Microsoft Official Curriculum course 10961.
With 10961, the goal was to provide a founding in PowerShell basics, in a somewhat product-neutral way. That is, the course doesn’t cover Exchange, or SharePoint, or AD; it focuses on pure PowerShell. Unlike its predecessor, 10325, the 10961 course kind of “stops short” of actual scripting. It shows you how to build a parameterized script, but doesn’t dig into advanced functions, debugging, error handling, and the like. There was a feeling - which has been largely upheld through customer feedback - that a sizable audience needed to get the shell basics under their belt, and weren’t necessarily comfortable leaping into coding. 10325 kind of breezed through scripting at a somewhat high level, and didn’t have time to offer much in the way of practices and other guidance, and it didn’t really set you up for building reusable units of automation.
That’s where 55039AC comes in. It is a scripting class, pure and simple, and it focuses on building reusable units of automation according to best practices and patterns. More time is devoted to design, structure, procedural error handling, and so on. There’s also deeper coverage of module building, including building custom formatting views, and there’s even an introduction to Workflow. Although designed for v3, the course is pretty version-agnostic, meaning it’s suitable for someone who wants to use PowerShell v2, v3, or beyond. And, because it’s a Courseware Marketplace offering, it’s compatible with Software Assurance (SA) training vouchers.
Training centers are welcome to combine 10961 and 55039 to create an “accelerated” class that includes heavier scripting coverage than 10961 alone. I do that myself, actually, although it’s a pretty hardcore week. If you’re interested in doing that, contact me and I can provide some of the accelerated-delivery outlines that I use.
55039’s modules are all standalone - with a twist. Students are encouraged to use and evolve a single code project throughout several modules. However, if you’re not teaching all of the modules, or if a student falls behind, each lab comes with a complete “starting point” that keeps everyone on the same page.
55039 has already been beta-taught, and of course I welcome feedback if you’ve taught the course or taken it as a student.
My company also offers licensing for this course outside the Courseware Marketplace, mainly geared to training centers who want an unlimited perpetual license to reproduce the course materials on their own. We know courseware costs are a significant concern, so we’re trying to offer something reasonable there.
Both 10961 and 55039 (or at least a subset of 55039; we’re still working on exactly what) will be considered pre-requisites for the upcoming 3-day 10962 course, which will focus on advanced PowerShell techniques for us in production environments, including database connectivity, report generation, and so on.

Why Get-Content Ain't Yer Friend

Mon, 21 Oct 2013 20:18:41 +0000

Well, it isn’t your enemy, of course, but it’s definitely a tricky little beast.
Get-Content is quickly becoming my nemesis, because it’s sucking a lot of PowerShell newcomers into its insidious little trap. Actually, the real problem is that most newcomers don’t really understand that PowerShell is an object-oriented, rather than a text-oriented shell; they’re trying to treat Get-Content like the old Type command (and why not?type is an alias to Get-Content in PowerShell, isn’t it?), and failing.
Worse, PowerShell has just enough under-the-hood smarts to make some things work, but not _everything. _
For example, this works to replace all instances of “t” with “x” in the file test.txt, outputting the result to new.txt:

$x = Get-Content test.txt $x -replace "t","x" | Out-File new.txtSadly, this reinforces - for newcomers - the notion that Get-Content is just reading in the text file as a big chunk o’ text.
Nope.
You see, in reality, Get-Content reads _each line of the file individually,_and returns _collection of System.String objects. _It “loses” the carriage returns from the file at the same time. But you’d never know that, because when PowerShell displays a collection of strings, it displays them _one object per line and inserts carriage returns._So if you do this, it’ll look like you’re dealing with a big hunk o’ text:

$x = Get-Content test.txt $xBut you’re not. $x, in that example, is acollection of objects, not a single string.
Never fear - you can make sense of this. First, if you use the -Raw parameter of Get-Content (available in v3+), it does in fact read the entire file as a big ol’ string, preserving carriage returns instead of using them to separate the file into single-line string objects. In v2, you can achieve something similar by using Out-String:

$x = Get-Content test.txt | Out-StringSo if you just need to work with a big ol’ string, you can. Alternately, you might find that some operations are quicker when you actually do work line-by-line. For example, asking PowerShell to do a regex replace on a huge string can consume a ton of memory; working with one line at a time is often quicker. Just use a foreach:

ForEach ($line in (Get-Content test.txt)) { $line -replace "\d","x" | Out-File new.txt -Append }Of course, don’t assume it’ll be quicker - Measure-Command lets you test different approaches, so you can see which one is actually quicker.
You should also consider not using Get-Content, especially with very large files. That’s because it wants to read the entire file into memory at once, at that can take a lot of memory - not to mention a bit more processor power, swap file space, or whatever else.
Instead, read your file from disk one line at a time, work with each line, and then (if that’s your intent) write each line back out to disk. Instead of caching the entire file in RAM, you’re reading it off disk one line at a time.

`$file = New-Object System.IO.StreamReader -Arg “test.txt” while ($line = $file.ReadLine()) {

Articles from October 2013 on PowerShell.org - Welcome Automaters!

PowerShell "Scripting and Toolmaking" Classroom Training Course Now Available to Microsoft Training Centers

Why Get-Content Ain't Yer Friend

$line has your line

The Shell vs. The Host

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