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Logical operators come into play when you have more complex expressions.

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So let me walk you through this.

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I'm going to start by assigning $i with a value of 4.

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And now I want to have an expression.

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I'll admit this is a little artificial,

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but I want to demonstrate the logical operator.

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The logical operator is ‑AND.

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There's no case sensitivity here with the operator.

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I just happened to put it in all uppercase so it stands

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out so I can see that it is an operator.

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So here's how the operator works.

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All of the expressions are evaluated, and then the ‑AND operator says,

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hey, if all of the expressions are true,

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then the whole expression has a result of true.

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Otherwise, the whole expression is false.

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So I've got two expressions here.

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I have a $i is less than or equal to 10.

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And we know that that is true because 4 is less than or equal to 10.

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And I want to know is the PSVersionTable variable,

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and then the PSVersion property, which is an object,

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and that object has another property called Major,

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which will be a number, is that number greater or equal to 7?

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Assuming I'm then running this on PowerShell 7, that will also be true.

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So I've got true and true, which means the entire expression will be true.

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And, of course, if one of the comparisons is false,

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then the entire expression is false.

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So now I have $i = 20, $i less than equal to 10.

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That is false.

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So even though the PSVersionTable.Major value is greater than or equal to 7,

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I have false and true, which means the entire expression is false.

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Related to this is the ‑OR operator.

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Same idea, I'm going to compare or evaluate all of these individual expressions.

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As long as one of them is true, then the entire expression is true.

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So now, even though $i less than or equal to 10,

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even though that part is false, because the PSVersionTable expression is true,

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the entire expression is true.

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And in PowerShell,

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you can also combine these logical operators if you have a really

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complex expression that you're trying to evaluate.

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So here I have a variable $1 = 20.

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I'm setting $name = "jeff".

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And now I have a complex expression, is $i greater than or equal to 20,

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and now I have a second part of that complex expression,

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is $name = "Jeff", or am I running a Linux machine?

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$IsLinux is a new PowerShell variable that will be true or false if I'm running

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on a Linux box that will have a value of true; otherwise,

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it will be false.

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If both sides of the ‑AND operation are true,

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then I have a complete result of true and PowerShell gives that to me.

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This is clearly a situation where parentheses really come in handy.

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Now they're not technically required,

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but they will make it easier for you to understand what PowerShell is doing,

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and you're less likely to run into an error or not get a

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result that is appropriate or correct.

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So what I'm doing here to reinforce the idea,

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so I've got the ‑AND operation has two things going on.

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I have $i greater than or equal to 20,

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and you can see the parentheses there I've colorized,

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‑AND, and then the set of outer parentheses controls the next expression,

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which is a nested ‑OR comparison.

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So I already know the left side of the ‑AND operation is true

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because 20 is greater than or equal to 20.

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Now on the right side in the ‑OR operation,

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I'm comparing is $name = "jeff", and we know that that is true,

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or am I running Linux?

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Now if I'm running this on a Linux box, that's going to be true,

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or if I'm running this on Windows, that's going to be false.

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But it really doesn't matter because as long as one of the expressions in

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the ‑OR operation that's inside the yellow parentheses,

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as long as one of those is true, then the whole operation is true.

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So I've got true on the left, true on the right,

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and so the whole operation then becomes true.

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Hope you kind of followed all of that.

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Another logical operator is ‑NOT.

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This can be a little confusing until you kind of

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get your head around the concept.

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So here's an expression.

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I want to use Test‑Path and verify that Windows Notepad actually exists,

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and it does.

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And so I get a value of true.

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That is the normal expected result.

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However, I can use the ‑NOT operator,

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and that will give me a result that reverses whatever the Boolean value is.

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So my expression becomes ‑NOT, and I find this easier to put in parentheses.

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If this whole expression or this Test‑Path,

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whatever that value is, the ‑NOT is going to reverse it.

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So because I already know that Test‑Path is going to return true,

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‑NOT reverses that.

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And so that gives me false as the result.

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Sometimes this becomes a handy little tool if you want to test

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for something and then reverse the result.

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That's what ‑NOT will do for you.

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The ‑NOT operator also has an alias of the exclamation point or bang

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symbol so that you can use that instead of ‑NOT.

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I tend to like using ‑NOT because that's clear.

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The exclamation point is a little more cryptic.

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You have to kind of know in advance what that means.

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‑NOT absolutely, hopefully, makes a little more sense to you.

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The ‑NOT operator is something that you probably will use a lot more when you get into PowerShell scripting.