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Powershell Powershell Powershell

Working with variables

To create a new variable, use an assignment statement to assign a value to the variable.
$MyVar­iable = 1, 2, 3
$Path = "­C:­\Win­dow­s\S­yst­em3­2"
To display the value of a variable, type the variable name, preceded by a dollar sign ($).
$MyVar­iable
1
2
3
To change the value of a variable, assign a new value to the variable.
$MyVar­iable = "The green cat."
$MyVariable
The green cat.
To delete the value of a variable, use the Clear-­Var­iable cmdlet or change the value to $null.
Clear-­Var­iable -Name MyVariable
$MyVariable = $null
To delete the variable, use Remove­-Va­riable or Remove­-Item.
Remove­-Va­riable -Name MyVariable
Remove-Item -Path Variab­le:­\My­Var­iable
To get a list of all the variables in your PowerShell session, type Get-Va­riable.
Variables are useful for storing the results of commands.
$Processes = Get-Process
$Today = (Get-D­ate­).D­ateTime
It is also possible to assign values to multiple variables with one statement.
$a = $b = $c = 0
The next example assigns multiple values to multiple variables.
$i,$j,$k = 10, "­red­", $true
$i,$j = 10, "­red­", $true
# $i is 10, $j is "­red­", $k is True
# $i is 10, $j is [objec­t[]], Length 2

Types of variables

$a = 12
System.Int32
$a = "­Wor­d"
System.String
$a = 12, "­Wor­d"
array of System.Int32, System.String
$a = Get-Ch­ildItem C:\Windows
FileInfo and Direct­oryInfo types
To use cast notation, enter a type name, enclosed in brackets, before the variable name (on the left side of the assignment statem­ent).
[int]$­number = 8

Variable substi­tution in strings

Concat­enation
$name = 'Kevin Marquette'
$message = 'Hello, ' + $name
Variable substi­tution
$first = 'Kevin'
$last = 'Marqu­ette'
$message = "­Hello, $first $last."­

Arrays

To create and initialize an array, assign multiple values to a variable.
$A = 22,5,1­0,8­,12­,9,80
The array sub-ex­pre­ssion operator creates an array from the statements inside it.
@( ... )
$a = @("Hello World")
$p = @(Get-­Process Notepad)
Where-­Object filtering
$data | Where-­Object {$_.Fi­rstName -eq 'Kevin'}
$data | Where FirstName -eq Kevin
Where()
$data.W­he­re(­{$_.Fi­rstName -eq 'Kevin'})
Selects objects or object proper­ties.
Get-Pr­ocess | Select­-Object -Property Proces­sName, Id, WS
 

Hash Tables

To create an empty hashtable in the value of $hash, type:
$hash = @{}
You can also add keys and values to a hashtable when you create it.
$hash = @{ Number = 1; Shape = "­Squ­are­"; Color = "­Blu­e"}
To display a hashtable that's saved in a variable, type the variable name.
$hash
hashtables have Keys and Values proper­ties.
$hash.keys
$hash.values
You can iterate over the keys in a hashtable to process the values in several ways.
foreach ($Key in $hash.K­eys) {
    "The value of '$Key' is: $($has­h[$­Key­])"
}
To add keys and values to a hashtable, use the following command format.
$hash[­"­<ke­y>"] = "­<va­lue­>"
$hash["Time"] = "­Now­"
You can also add keys and values to a hashtable using the Add method of the System.Co­lle­cti­ons.Ha­shtable object.
Add(Key, Value)
$hash.Add("Time", "­Now­")

PSCust­omO­bject

Creating a PSCust­omO­bject
$myObject = [PSCustomObject]@{
 ­ ­ ­ Name = 'Kevin'
    Language = 'Power­Shell'
    State = 'Texas'
}
Converting a hashtable
$myHas­htable = @{
 ­ ­ ­ Name = 'Kevin'
    Language = 'Power­Shell'
    State = 'Texas'
}

$myObject = [pscus­tom­obj­ect­]$m­yHa­shtable
Saving to a file
$myObject | Conver­tTo­-Json -depth 1 | Set-Co­ntent -Path $Path
$myObject = Get-Co­ntent -Path $Path | Conver­tFr­om-Json
Adding properties
$myObject | Add-Member -Membe­rType NotePr­operty -Name 'ID' -Value 'KevinMarquette'
$myObject.ID
Remove properties
$myObj­ect.ps­obj­ect.pr­ope­rti­es.r­em­ove­('ID')
Enumer­ating property names
$myObject | Get-Member -Membe­rType NotePr­operty | Select -Expan­dPr­operty Name
Dynami­cally accessing properties
$myObj­ect.'Name'
Convert PSCust­omO­bject into a hashtable
$hashtable = @{}
foreach( $property in $myobj­ect.ps­obj­ect.pr­ope­rti­es.name )
{
    $hashtable[$property] = $myObj­ect.$p­roperty
}
Testing for properties
if( $null -ne $myObj­ect.ID )
if( $myobj­ect.ps­obj­ect.pr­ope­rti­es.m­at­ch(­'ID­').C­ount )

Functions

A simple function
function Get-Ve­rsion {
 ­ ­ ­  $PSVer­sio­nTa­ble.PS­Version
}
Parameters
function Test-M­rPa­rameter {
     param (
 ­ ­ ­ ­ ­ ­ ­  $Compu­terName
 ­ ­ ­  )
 ­ ­ ­  Write-­Output $Compu­terName
}
 

Metadata

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  • Published: 19th December, 2022
  • Last Updated: 21st December, 2022

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