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Now the whole point of working with variables is to

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make it easier to use PowerShell.

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For example,

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I'm going to create a variable called $logs and it's going to

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contain the results of the Get‑Winevent command and that's going

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to get the 1000 most recent events.

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I'm giving you some command examples that might take a long time to run,

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although in this case, it's really not going to take that long at all.

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But now I have a variable that holds the results of that command.

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I can now work with those objects just as if I had run Get‑Winevent so

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I can say take $logs and pipe it to Group‑Object.

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And so, I want to group on the LevelDisplay Name with NoElement.

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So I just want to see hey,

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what types of entries have I gotten in the system log for the

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last 1000 record or maybe I want to take all those logs and

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group them on the provider name.

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Same idea. What sources of problems or information

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am I getting in the event log?

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I don't have to rerun Get‑WinEvent.

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I can use the results that are saved to that variable.

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Now here is one that's a little more complicated.

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So let's take $logs and I'm going to pipe this to where object where the

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provider name is equal to service control manager, and I want to select the

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TimeCreated LevelDisplayName and the Message.

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So there we go.

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So again, I don't have to rerun Get‑Winevent.

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I can use the saved results really quite handy. Now

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sometimes the variable might change.

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So let me show you what I'm talking about.

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Let's go back and rerun that veg command to Get‑Vegetable,

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everything vegetables starts with c, save it to $veg.

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Alright, so there we can see. Now look at the corn object there,

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see there are 12.

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I'm going to use Set‑Vegetable and change the corn value to 1 and

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I'm using ‑Passthru so it'll update the results.

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Go back and look at the variable now, that changed the value.

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This doesn't happen all the time.

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Sometimes it does, sometimes it doesn't, there is no way for you

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to know unless you try it and see for yourself.

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It doesn't always, but it might. For example, here, look at this.

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Get‑Service BITS, we'll save that to variable $bits, and if I select the

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name and StartType, you can see it is set to Manual.

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If I change the StartType to Disabled and then select it

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again because I'm going to do ‑PassThru, so that changed the

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actual service and it disabled it.

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However my bits object, the variable, shows a StartType of Manual.

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So in this case, there is no connection between the

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variable and the source object.

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The next thing to take into account with variables is type.

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So let's go back and recreate $a equals to 2.

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And as I have shown you, $a, if I pipe this to Get‑Member, is an integer.

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The variable itself really is meaningless as what's

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inside the variable that count.

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I can do things like $a + $a and I get 4.

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So let's assign a variable $i. Now notice here I'm putting this

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in single quotes, which makes it a string.

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You can even see the color coding change that PowerShell did.

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Now let's try to add this because I think oh yeah,

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it's going to be, it didn't work.

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Nope. I was expecting 10, but I got 55 because PowerShell saw that I was

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treating that as a literal string 5, and so it just gave me 2 literal

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strings put together. And you can verify this if I pipe $i to Get‑Member

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and you can see that it is a string. Get‑Member will be a cmdlet that you

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will use all the time.

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Now what you could do is I can cast or tell PowerShell hey create $i,

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but make it an int32 and give it a value of 10.

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Normally, PowerShell if I just $i equals 10, it would do that automatically.

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You don't always have to do that.

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Sometimes it makes more sense to you if you see it go oh

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yeah that reminds me that's an int32.

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Now if I multiply that variable by 2, I get the value that I am expecting.

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Where it gets tricky or sometimes helpful is with dates. So I can take a

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string 12/31/2022 and turn that into a datetime object saved to variable $d

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and you see PowerShell treats it as a datem and if I pipe to Get‑Member,

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sure enough you can see that it is a system.datetime object. Now this is

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where it gets tricky and where you have to be careful. So I have $d,

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remember I just created it as a date. Now I'm trying to assign it a value

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of the string foo, and PowerShell will complain because it says,

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hey,

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$d is a datetime object and you're trying to give me a string and I can't

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make foo into a date so I'm going to give you an error.

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This is where you need to be careful with your variable names so that

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you make them meaningful and you're not reusing variables, although I do

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all the time and you probably will too, although just be aware that you

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may encounter this problem if you created a variable and forgot what

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type that you cast it to.

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So there are ways around that. I can say hey take $d and

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create a string of foo and now that will work.

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So you really need to be careful with the variable

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names and how you are using them.

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Let me show you one more slightly advanced alternative.

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So I'm going to take $t and assign a string to it.

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And now you can see $t, it looks like a date, but really if I pipe to

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Get‑Member, you can see, sure enough, it is a string, but I can tell

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PowerShell, hey I want to treat that as a datetime object.

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Take $t and treat it as a daytime object and PowerShell certainly does.

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This doesn't change the value of t.

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T Is still a string which has a length property.

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So all I did was a one‑time operation that just said take $t,

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turn it into a date, write it to the pipeline.

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It leaves t alone, it doesn't change that at all.

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That's again,

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something we'll cover a little bit later in the course,

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but I wanted to give you a taste.

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Alright, so that's a look at using variables in PowerShell and why you might

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want to do them, some of the things you might run into. Let's go back and look at some more slide.