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With all of this,

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it's time to go back into PowerShell so I can show you

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how to work with objects one at a time.

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Hopefully you can take advantage of the PowerShell pipeline and manage at scale,

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but when you can't, you'll have to do things like this.

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Alright,

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I'm going to assume that you're going to read the help for foreach‑object.

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Let me just get in and demo it.

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Let me begin with at least showing you the demo from the slide,

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just so you can see this in action.

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So 1..10, remember that dot dot is the range operator,

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foreach‑object that comes through the pipeline,

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I'm going to multiply that object, in this case the numbers 1 through 10,

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by 2, and PowerShell then writes that object to the pipeline.

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And just to show you that this is still going on,

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this is still PowerShell pipeline stuff,

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let's rerun this command, and I'm going to pipe this now to measure‑object.

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I don't have to specify a property here,

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because the number itself, the object, that is the property,

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that is the value.

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So if PowerShell does not see a property for measure‑object,

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it just assumes that you must be piping in a number,

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something that measure‑object can work with.

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And so the AllStats will go through, and I can get the count,

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and again, the average, the sum,

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all the other statistics that measure‑object will provide.

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Let's do one other here.

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Let's do one more example,

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and this is kind of to reinforce something we

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looked at in the last demonstration.

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So I'm going to do the foreach, and let's measure the object,

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get all those statistics, but, you know,

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I don't want to see the Property property,

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that's blank, just show me the ones that have the numbers there.

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So it's much nicer, cleaner output,

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we kind of saw that in a previous demonstration.

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Let me also show you one other example here,

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because you will see this out in the wild,

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out, people post this and use this all the time.

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That percent symbol that you see there is the alias for foreach‑object.

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Personally, I'm not a big fan of that, because if you see that,

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as you see that here, and you're new to PowerShell,

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you have no idea what that means.

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It's cryptic.

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You have to go look up, okay, what does percent symbol indicate,

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whereas if you see foreach‑object, that's at least a little clearer.

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But the result is still the same,

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for each number that comes through the pipeline,

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divide it by 2, and there you can see the results.

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When you're working with PowerShell interactively in the console,

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if you want to use the percent symbol, go right ahead.

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It's just as easy to start typing foreach and hit Tab

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and let PowerShell Tab complete it.

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Now let's look at this with real objects other than just number.

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And, again, to reinforce the concepts,

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we'll start with my generic Get‑Vegetable command.

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So we do Get‑Vegetable, and I'm going to look at get‑member here,

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because there is a method here called Peel.

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The Peel method has no parameters.

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That's why you see just the parentheses with nothing inside.

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If I look at my output for this cmdlet and look at the objects,

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there is a property that indicates whether something is peeled or not.

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So right now you can see nothing is peeled.

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There are no commands that will allow me to peel or to invoke that method,

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so if I want to use that method, I have to do it individually.

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So I'll just grab, say, the Carrot vegetables.

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For each Carrot object that comes through the pipeline,

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I'm going to invoke the peel method.

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So $_ is the current object, and then .peel,

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and then in parentheses,

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you have to include the parentheses for the method even

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if it doesn't have any parameters.

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Now, that method doesn't write anything to the pipeline,

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so I don't see a result, but we can easily verify that.

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Let's just get all the C vegetables, and again,

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just select a few properties like the Name and IsPeeled.

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So there we go, so Carrot, you can see there actually IsPeeled,

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so I know that that method did its thing.

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If I wanted to use that method again, I had to invoke it or use it one at a time.

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Let's look at another example here.

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I'm going to change to my work folder here,

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and I'm going to create two test files, and let's do test.txt,

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and then I'm just going to, again, create text2.txt.

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All I'm doing is running get‑date and sending the output instead

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of to the pipeline and showing on my screen,

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I'm sending it to the text file.

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Now if I look at my files here, and select the name and attributes properties,

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you can see the results there.

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Now,

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I happen to know that if I look at a particular file

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like test.txt and look at get‑member, that there is a method called Encrypt.

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So I want to encrypt each of the files, or not all the files,

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I want to encrypt my test files that I just created.

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There's no cmdlet out of the box that will do that for me.

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I can use that method, but again,

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I have to invoke it or run it for each object that comes through the pipeline.

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So let's do a listing of my test.txt files.

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For each object, I'm going to invoke or run that encrypt method,

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and again, it's all done.

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The method doesn't write anything to the pipelines, so I don't see a result.

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But I can verify the results,

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let's rerun the directory listing and select the name and attributes,

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and now you can see that those files actually are encrypted,

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so that did work.

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Sometimes you want to take advantage of the foreach,

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because there is no other way to do something using the PowerShell pipeline.

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Now what I'm about to show you is not necessarily the

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only way to accomplish this task, but it's a good illustration,

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I think, of the concepts here.

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So if you look at help, for Get‑Volume, there is a parameter called cimsession,

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which, in essence, is a remote computer name.

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Don't worry too much about cimsessions and remoting,

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because you may not have gotten into that yet.

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If I give a computer name a value to cimsession,

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it will connect to that computer and get me the volume information.

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I have a text file in my scripts folder called servers.txt,

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and you can see the servers that are listed there.

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I'd like to be able to pipe this list to Get‑Volume and get the

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C drive information for all those servers,

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so I might try something like this, get‑content and then pipe it to Get‑Volume.

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And that fails, and the error message tells you that it fails.

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Scroll back up here.

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If you looked at the help output,

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you can see that this parameter does not accept pipeline input,

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so in order to give it a value, I'm going to have to do it one at a time.

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Technically,

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I could do multiple values at the same time because see that

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cimsession and the little double square brackets,

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I could do Get‑Volume ‑cimsession server 1,

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server 2, server 3, all separated by commas,

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but, you know,

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I want to take advantage of the pipeline. So I can do something like this.

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So let's get my list of servers and the whole

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expression I'm going to save to a variable,

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$c.

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For each server name that comes through that list,

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I'm going to assign it the value to cimsession,

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to that parameter, and we're going to get Drive C.

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PowerShell will run for a moment and saves the results to $c.

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Pretty cool, so that worked, I was able to tell PowerShell,

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get the list of computers one at a time,

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call Get‑Volume and pass that computer name and feed

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that into the cimsession parameter.

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But, you know, here,

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let's continue our little exploration here with

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these cmdlets to work with objects.

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Let's take that variable and let's pipe to Select object,

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and let me select a few properties.

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Now I know from piping this to get‑member, I know what the property names are.

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So I want to see the computer name because I can't tell that

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from the output that I see there from $c,

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the DriveLetter and any parameter that starts with Size,

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and once again, I'm using the wild card there.

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Cool, that's a much easier output.

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Now I can see the Size and SizeRemaining of each of

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the servers that were in my list.

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Eventually you'll learn some other tricks to format those numbers into

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megabytes or gigabytes or something a little more useful to you,

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but for now, PowerShell selected what I needed and presented it on the screen.

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How about a more complete example of all of this?

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Let's try a directory listing of windows and get all the

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files in it, and let's send this to group object and group

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on the extension property.

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Then we'll select some properties, we'll do the Name,

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Count, and now I'm going to do something slightly advanced.

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You'll see examples of this in the help for select object.

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I'm going to create a custom property on the fly,

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don't worry too much if you don't fully understand it at this point.

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I'm going to create a property called Size,

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and the value of Size is going to be the results of this

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Expression script block that I'm doing.

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And I'm going to take the group object, remember,

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$_ means the current object in the pipeline.

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So I have a group object that I'm processing.

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Remember,

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the group property is a list of all of the related files,

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in this case, grouped by extension.

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So I'm going to take all of those files and pipe them to Measure

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object and measure the length and get the sum.

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Now all I want is just that sum value,

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so one way to do that is to pipe this to select object and tell

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it to use expandproperty on that sum property.

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That'll just give me the value,

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it won't give me an object with a single property of sum.

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That value then gets assigned to the Size property that I'm creating on the fly.

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So I got a new object going through the pipeline.

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I can sort on that new property that I created in descending

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order and then Select just the first 5.

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So now I can see in my windows folder these are the file extensions that are

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using the most space or have the the largest number of files,

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and, not surprisingly,

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the executable files in C windows are taking up the most space.

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There are some alternate ways of using foreach‑object,

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which I at least need to show you,

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even though I don't necessarily recommend using them,

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and I don't use them really myself, but let me show you.

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So let's go to my scripts folder, and I'm just going to create,

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this is a good example of using that range operator,

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and I'm going to create test files.

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So for each number that comes in,

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I'm going to take Get‑Date and pipe it to Out‑File and create a

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file called secret‑ whatever the number is,

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secret‑12345.dat.

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The contents would just be the date.

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And if I take a look at the list, so I just created those files.

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Now if I wanted to modify, say I want to hide those files,

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I need to adjust and modify the attributes property of those files.

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One way to do it is like this.

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I can get my directory listing of those files,

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pipe them to foreach, instead of using $_,

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technically you're allowed to use something called

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psitem. $psitem is the same thing as $_,

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it means the current object in the pipeline,

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and I'm just telling it add Hidden to the attributes property.

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The += sign is a special operator that says add it to an existing collection.

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Now that they're hidden,

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if I want to see them actually I have to use the ‑force parameter,

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and in the output there you can see that they are in fact hidden.

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I'm not a big fan of $psitem.

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For one, not a lot of people have used it,

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and I think it's just kind of a little more confusing,

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personally, myself.

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I think you should be able to do $_, so in other words, do this.

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So I get all my files again that are hidden,

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and in this case I'm going to undo the operation using

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$_ and remove that Hidden attributes, and now I've unhidden those files.

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I think that's a much cleaner approach, it's more consistent, but pick one.

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If you happen to like $psitem, then use that all the time.

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The worst thing to do, though,

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is to go back and forth and have some code using $_ and some

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using $psitem. Pick one and go with that.

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And there you can see that the files are in fact now unhidden.

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One thing I want to point out, though, with foreach‑object,

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do not, I mean it'll work, because I'm going to show you here that it will work,

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don't do this.

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Don't say, hey, I want to get a list of the files,

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but for each one, just show me the name property.

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Don't do that.

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This is what we used to do with VBScript and with

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other kind of old legacy‑style tools.

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This is where you're thinking like text.

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You're saying, give me this thing, but just show me the text.

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You don't have to do that one at a time, even though, yes, I know it works.

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When I see something like this, or if you see something like this,

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that should be your clue, okay, this person does not fully,

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they haven't gotten their head around this objects‑in‑the‑pipeline paradigm.

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The PowerShell way to do it would be this.

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If all I want to see is the file name, then just tell PowerShell,

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get me these file objects, and then just select the name.

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In this particular case, what, remember, our PowerShell is doing,

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it's creating a custom object, in this case with a single property called Name.

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If you truly just want the values, say, for a text list,

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you can tell PowerShell to expand that property,

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so we'll just select object, expand that Name property.

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Now I don't have that little name header,

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that's my clue that this is not an object,

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it's just a list of names.

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And, in fact, once you get more proficient in PowerShell,

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you can even shortcut all of that and just use syntax like this,

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gives me the same results.

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So the command inside the parentheses runs first,

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and then I can use the .name property and get the name

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property of all of those objects.

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So implicitly PowerShell is kind of doing a foreach object,

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don't worry, you don't have to get that way right now, but I wanted to point that out to you.