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We've been so far working without cmdlets that produce

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something at the end, whether that be a file or a printed

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document or something on the screen.

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Out‑Null is the only out cmdlet that actually doesn't give us any output.

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Let's jump in and explore.

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Let's launch the help with help out‑null. So Out‑Null is

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responsible for hiding the output of a command instead of

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sending it down the pipeline or displaying it.

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There's only one parameter here,

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which is InputObject, being the object that we want to work with.

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And the information that's here in this description is

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really important to let sink in.

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So the Out‑Null cmdlet sends output to NULL, which, in

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effect, removes it from the pipeline and prevents it from

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being displayed to the screen.

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So do be aware of exactly what you're doing when you use

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Out‑Null. Why might you want to use this?

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Well, let's take a look at an example.

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I'll use the New‑Item command to create an item called test,

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and I'll use the ItemType parameter to configure that as a

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directory. That will create a new folder in the C:4 drive called

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test. And by default, the cmdlet New‑Item outputs all of this

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information to the screen when it gets run.

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Now, I'll get rid of that test folder by using Remove‑Item, and

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let's rerun the New‑Item cmdlet, but this time we'll pipe it across

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to Out‑Null. This time we get nothing returned to us on screen, but

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if I do a Get‑ChildItem, you can see here that the test folder was

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still created, so the cmdlet did run successfully.

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It just didn't send its normal output to the screen.

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When might you actually use this?

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Well,

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some common scenarios or when you simply just want to suppress output that's

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sent to the PowerShell console like we did a moment ago.

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There are also times when you might be writing a function or a script,

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and you might be creating something that's reusable by other people like

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a module that's published to the PowerShell gallery.

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And some of those commands that you end up using in your own

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functions and modules could end up returning some unwanted

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results like this that really aren't useful,

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so you may just want to silence that output.

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We briefly saw this in the help at the start.

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But if I use New‑Item again to try and create a directory and

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send that to out‑null, at this point that would work just fine,

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but let's pipe that down to Get‑Member.

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And, yeah,

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PowerShell gives us an error because out‑null is actually

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removing that object from the pipeline entirely.

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So nothing is being sent across the pipeline to Get‑Member.

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Something to be aware of is that Out‑Null,

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by default, is responsible for dealing with these success stream,

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which is stream number 1 in PowerShell.

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There are other streams that are used for messages like errors,

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warnings, and for both.

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So if I run a command that I know will fail like Get‑ChildItem

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potato and then pipe that across to Out‑Null,

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we will still get the error message shown on screen because

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Out‑Null is only suppressing the success stream.

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It's not working with any of the other streams in PowerShell.

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Let's take a look at a bit of a nuance here. So I'm going to

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create a new variable named $dir, and in that we'll do

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Get‑ChildItem and pipe that to Out‑Null. We get no output as

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expected, but if I run $dir on its own,

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you might've expected to see the results of Get‑ChildItem to be shown on screen.

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What you can do is enclose the first section in parentheses,

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though now if we run $dir, we get the results of that Get‑ChildItem command.

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Lastly, while we have been looking specifically at Out‑Null in this clip,

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I want to expand on that a little bit and let you know about some other ways to

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null the output of commands because there's several popular ways to do it, and

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some of the other ways do have some speed benefits,

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too.

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To start with, I want to create a variable,

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and I'm going to set it as a New‑Object with the type

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of System.Collections.ArrayList.

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So this will allow me to store items here as an array. If I

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type $MyArray and then use the Add operator, I can specify a

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string of text to add into the array,

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so I'm going to call this Thing1. Notice here that by default this returned an

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output of 0. Not exactly helpful is it? Let me do this again, and this time I'll

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add Thing2. And this time we get an output of 1.

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And just for good luck,

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one more time for Thing3, and this time we get an output of 2.

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The output that's being displayed there is what number the

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object is in the array that we're adding to.

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But for my purposes,

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the output really isn't needed nor helpful, so let's suppress it.

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I'll run it again for Thing4, but this time pipe it to Out‑Null.

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Okay, no output this time, which is good.

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And if I check the values in the variable,

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we've got Thing1 through Thing4. Awesome.

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Let's check out a few other ways to null output.

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I'll run the same command to add Thing5 into the array, but this time I'm going

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to use one of the redirection operators that we looked at back in the out file

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clip, and I'm going to redirect it to $null. In PowerShell, $null is an

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automatic variable used to represent null,

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and it will treat $null as an object with a value of null.

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So again, no output was seen on the screen.

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And if we check the variable again, Thing5 has been added in.

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We could also make use of $null at the start of the command and then

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put an equal sign and then run our command. Again,

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no output.

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And if we take a look at the variable, Thing6 has been added in.

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And lastly,

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this one is more of a raw programming way to achieve the same

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thing, but you can cast the command to void by using the square

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brackets and the word [void], followed by the command that you are

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wanting to suppress the output on. Again, we don't have that output

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here in the console.

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And if we check that variable one more time,

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Thing7 absolutely got added in there at the end.

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There were a couple of reasons I wanted to show you these extra ways of

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working with null other than just the Out‑Null command.

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The first one really was just for completeness so you're

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aware of them and that you can use them.

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You'll often see examples of these being used,

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especially the redirection to $null and $null =. But also, most,

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if not all,

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of these methods on screen are actually faster than

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using the Out‑Null cmdlet as well.

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If you're processing a lot of information and want to suppress the output,

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make sure you use the cmdlet called measure command and try a few different

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ways to see which one is going to be most performant for you.

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These examples on screen for the most part avoid the pipeline, which can add some additional processing time to your cmdlets.