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So with that, let's jump into PowerShell one more time,

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and let me show you some of these other variable options in action.

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Let's first look at Tee‑Object.

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So I'll run my Get‑Vegetable command and say,

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Get me all the root vegetables,

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and I'm going to pipe them to Tee‑Object and use the

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‑variable parameter and give it a name of root.

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You can give it whatever name that you want.

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What Tee‑Object is doing is sending the output to two places.

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It sends one output to the screen so I can see my results,

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and it also saved the output to a ‑variable root.

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I encourage you to look at the help for Tee‑Object or some

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other things that you can do with it.

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But variables are what we care about for right now.

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If I type $root, I get the results of the variable.

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Now, yes, I could have done $root = Get‑Vegetable,

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but then I'd have to take an extra step.

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This is just a way of using Tee‑Object, which has an alias of Tee,

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by the way, of making it easy to kind of get your cake and eat it too,

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get the results and save the results to a variable.

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So with the results, I can then say, Hey,

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I want to sort them on the count in descending order

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without having to rerun the original command.

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And, again, look at help for Tee‑Object,

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you can see there are some other ways that you might want to use it.

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Now I want to look at the common parameter, ‑OutVariable.

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So let's go back and look at Get‑Vegetable,

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and you should see this in pretty much any PowerShell command.

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Notice that CommonParameters section there in the help.

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When you see that, that means that the command will take ‑OutVariable,

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which has an alias of ‑ov.

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So now that I know that this command can do that, here's what we can do.

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So I can run Get‑Vegetable ‑OutVariable v.

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The nice thing about using ‑OutVariable is that you can save the output of

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individual segments of your pipeline expression to a variable.

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So the output of Get‑Vegetable will be saved to $v.

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I'm going to pipe this to where‑object where the count is

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greater than 10 and save that output to $w.

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So there are the full results.

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But I also now have variables $v and $w,

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so $v I can say, Hey, sort me on the name.

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So $v is all the vegetables.

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So there are the vegetables I got from the first part saved as $v.

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And $w is the where‑object part.

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Hey, I want to show the filtered objects,

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so that's filtered vegetables, and sort them on the count property.

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Very handy technique.

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I use this quite a bit.

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It's very useful if you're trying to troubleshoot or want to

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work with individual chunks of data separately.

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You can even append to that value.

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Let me show you how.

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So I'm going to do get‑service and find all the

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services that start with the letter b.

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And here I'm using the parameter alias ‑ov.

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We'll save that to b.

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So there are the results.

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And if I look at $b, I get the same results.

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I'm going to rerun the command.

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Thus, I'm getting all the c services,

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and I'm going to send them also to ‑OutVariable.

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But notice that plus sign in front of b.

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So this is going to append this output to $b.

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So here's the output from the command.

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Now if I look at $b,

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I can see there all my b services and then all of the c services.

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They've all been added together to that common variable $b that I created.

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There is a help topic that you can look at,

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help about_CommonParameters, give you a little more detail about ‑OutVariable,

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as well as some other parameters that you might want to take advantage of.

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The last variable option I want to show you is

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‑pipelinevariable. Now this is an advanced concept.

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This is not something that you will need to use all the time.

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It's kind of a special use case scenario.

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It's really designed when you have a long‑running PowerShell

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expression and you need to get information from one part of a

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pipeline into another part of the pipeline.

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This is what fixes that problem.

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‑OutVariable only writes the results and finishes that

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variable after that segment completes,

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and you cannot reference that variable inside the pipeline.

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You can only reference it after the whole expression has finished.

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So here's how this works.

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And it will really help if you can try to visualize,

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and I'll try to explain what Powershell doing here,

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if you can visualize what is going on.

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So we're going to start with the numbers 1 to 10 using the range operator.

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For each of those numbers, I'm just going to write it to the pipeline.

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That's what's in the curly braces.

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I'm also using the ‑pipelinevariable,

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so I'm going to save the output of this little segment to $a.

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The numbers are then going to be written onto the pipeline to the next step,

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which is another ForEach‑Object where I'm going to multiply

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the number that comes through the pipeline,

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the $_, by the value of $a.

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Now this is where the ‑pipelinevariable gets a little tricky.

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‑Pipelinevariable is basically going sequentially.

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So $a will have the numbers 1 through 10.

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So it's got 10 items.

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So when I go through the ForEachObject for the second time, $b is going

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to take the number and then get me the first number and then get the

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first element of $a, the second number and the second element of $a. So

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it lines everything up. In this case, the effect will be multiplying

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each number by itself. And then that result will be saved to

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Select‑Object where I'm going to create some custom properties, so the

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value will be $a.

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So I'm using the ‑pipelinevariable from the first part,

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which would be the numbers 1 through 10.

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I'll then create a second custom property called Square.

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And that's the value from $b.

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And then I'm going to create another property called Cubed,

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where I can take $b*$a.

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And there are the results.

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So if you can kind of visualize what PowerShell is

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doing, that sort of makes sense.

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I'll admit this is a bit of an artificial example.

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I tried finding some real‑world examples, and I really

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don't have many in my own library.

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I asked some other people and they'd say, Yeah,

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I really don't use it that much because there are other ways to

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use PowerShell that don't have to rely on the ‑pipelinevariable.

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Not everything in PowerShell has to be written as a one‑line

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expression as I've done here.

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Sometimes it is easier and makes more sense to break

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things up into multiple steps.

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So let's do this. I'm going to basically recreate the output but through

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multiple steps, and this might be easier to follow.

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So $a is 1 through 10. $b takes $a, and then for

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each one multiplies it by itself.

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So this is kind of behind the scenes what the ‑pipelinevariable is

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doing. I'm just doing it explicitly step by step in PowerShell. So

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now I'm going to use a scripting construct,

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although you can use it in the PowerShell pipeline, the for construct.

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So I'm going to go through and get the index of $b and select and create

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my custom objects here, and I'm going to create the Cubed value. And

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there we go. So I get the same results whether the second example with

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it broken out step by step makes more sense to you or the

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‑pipelinevariable makes more sense.

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That's fine. That's really kind of up to you. Again,

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this is not something you're going to use all the time,

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but I at least wanted to make you aware of it because you may see someone

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using ‑pipelinevariable, and I want you to understand what it is that they

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are doing. And that wraps up our exploration of variables in PowerShell.

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They're really not that difficult.

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$a equals foo, and then use $a.

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Save the results of a long‑running command to a variable.

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You're good to go.

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It's really not that complicated.

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I may have made it seem a little more complicated because I wanted to show

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you all of the commands and give you some insights into the nuances of using

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variables and the ways that it can trip you up,

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but also how it can make your life easier.

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So take a quick break,

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refill your beverage, and then come back, and let's learn more about the PowerShell language.