PowerShell for IT Professionals [#11] – Variables

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In this lesson we’re going to learn how what Variables are, why it’s good to use them and how to actually create them. We will then assign various values to variables to and use them solely, and in parameters.

We will also have a look at foreach loop so that we can e.g. ping multiple computers using single variable with multiple objects in it.

Exercises

  • Use Get-Command to find all commands that allow you to manage variables. Then find the command that let’s to display all currently available variables.
  • In notepad, store a few hostnames/ip addresses each in separate line
    • Use Get-Content commandlet to read the content of the file just created
    • Store the content of the file into a variable
    • Display all the objects of variable – it should be exactly the same as content of the file
    • Use foreach loop to ping all the servers from your variable

Common variable types

  • [string] – Text string
  • [char] – a single character
  • [bool] – Boolean (can be either $True or $False)
  • [int] or [int32] – 32-bit Integer
  • [long] or [int64] – 64 – bit Integer
  • [DateTime] – Date and time

Commands used in the lesson

# Let's work on simple string
"Kamil Procyszyn" 

"Kamil Procyszyn" 
| GM

$name = "Kamil Procyszyn"

$name| GM

# Same with numbers

3 

3 | GM

3 + 5

$a = 3

$a | GM

$b = 5

$a + $b

# Let's check what will happen after changing the value of one of properties

$a = 10

$a + $b

# Let's use variables with parameters

$server = "PS-SVR1"

Test-NetConnection $server

Ping $server

Get-Process -ComputerName $server

# Variables give access to methods

$name

$name | GM

$name

$name.ToUpper()

$name.ToLower()

# We can store output of commands to variables and access their properties

$services = Get-Service

$services

$services.name

# We can obviously pipe

$services | where {$_.status -like 's*'}

# Storing multiple objects in variable

$computers = 'ps-svr1','localhost','1.1.1.1','8.8.8.8','kamilpro.com'

$computers

$computers[0]

$computers[2]

$computers[-1]

# Let's try to ping all of them

ping $computers

Test-NetConnection $computers

# If command doesn't allow to provide an array, we can loop through it

foreach ($c in $computers) {ping $c}

foreach ($c in $computers) {Test-NetConnection $c}

foreach ($c in $computers) {nslookup $c}

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