PowerShell

PowerShell: Playing with text or how to get every x line from text output (trim,replace,split)

I’ve always struggled with text. Now I really hate text. I love objects. But sometimes you can’t avoid these non-object-oriented characters coming from somewhere else. This blog post is about text and its formatting. We will concentrate on the methods trim, replace and split. And we will use an example: arp -a.

Starting Point (arp -a)

Where do we start? As promised we are going to use the good old arp command. Let’s have a look at arp. It’s result is plain text.

Unbenannt.PNG

Let’s say we would like to list only the IP Addresses without the other stuff. It should look like this:

Unbenannt.PNG

How to get started? First, we are going to delete all whitespaces with the trim method.

Trim

Trim can help you removing all those annoying whitespaces at the beginning and at the end. Let’s do it.


$a=arp -a

$b=$a.Trim()

Unbenannt.PNG

Nice one. Comparing to the previous they are all gone.

Unbenannt.PNG

Skip

Our next part is to remove the first three lines.

unbenannt51.png

This takes us to skip. Let’s move on and remove the first 3 lines with Select-Object.


$c=$b | Select-Object -Skip 3

And finally they are gone.

Unbenannt.PNG

Now we have a good basis.

Replacing all whitespaces with one whitespace

Let’s go on with removing all unnecessary whitespaces.

1.PNG

With this simple replace statement we replace all whitespaces (\s+) with one whitespace.


$d= $c -replace '\s+', ' '

Unbenannt.PNG

Splitting

At this stage we arrive at split. All we need is one row with all the values.


$e=$d -split(' ')
$e

Unbenannt.PNG

But we just want the IP-Addresses. That’s why we need to get to every third line. Now we are coming to the last part that is the most demanding one: Getting every 3rd line.

Looping through every 3rd line

Our goal is clear. List only every 3rd line.

unbenannt59.png

We start at zero. Then we define the end of the loop. Then we define every 3rd line.


$f=for ($i=0;$i -lt $e.count;$i+=3) {$e[$i]}
$f

Unbenannt.PNG

Great, we’ve reached our goal.

All together

To get to the point, all at once in a slightly different order.


$a=arp -a | Select -Skip 3
$b=$a.Trim() -replace '\s+',' ' -split '\s'
$c=for ($i=0;$i -lt $b.count;$i+=3) {$b[$i]}
$c

Unbenannt.PNG

Another final example (quser)

How to get the logged in user from quser? I’m talking about this. Simple text again.

2.PNG

What I would like to mention first is that there are hundreds if not thousands of ways to get the username. Here is my approach which is quite similar to the shown above.

It is not as difficult as the one shown above. All we need is the username. No loop. Let’s trim first. The username is in 8th place.


$a=quser
$b=$a.trim() -replace '\s+',' ' -replace '>','' -split ' '
$b[8]

Unbenannt.PNG

That’s it for today. Don’t worry about dealing with text 😉

Categories: PowerShell

Tagged as: ,

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.