How can I pass an argument to a PowerShell script?

Tested as working:

#Must be the first statement in your script (not counting comments)
param([Int32]$step=30) 

$iTunes = New-Object -ComObject iTunes.Application

if ($iTunes.playerstate -eq 1)
{
  $iTunes.PlayerPosition = $iTunes.PlayerPosition + $step
}

Call it with

powershell.exe -file itunesForward.ps1 -step 15

Multiple parameters syntax (comments are optional, but allowed):

<#
    Script description.

    Some notes.
#>
param (
    # height of largest column without top bar
    [int]$h = 4000,
    
    # name of the output image
    [string]$image = 'out.png'
)

And some example for advanced parameters, e.g. Mandatory:

<#
    Script description.

    Some notes.
#>
param (
    # height of largest column without top bar
    [Parameter(Mandatory=$true)]
    [int]$h,
    
    # name of the output image
    [string]$image = 'out.png'
)

Write-Host "$image $h"

A default value will not work with a mandatory parameter. You can omit the =$true for advanced parameters of type boolean [Parameter(Mandatory)].

You can use also the $args variable (that's like position parameters):

$step = $args[0]

$iTunes = New-Object -ComObject iTunes.Application

if ($iTunes.playerstate -eq 1)
{
  $iTunes.PlayerPosition = $iTunes.PlayerPosition + $step
}

Then it can be called like:

powershell.exe -file itunersforward.ps1 15

Call the script from a batch file (*.bat) or CMD

PowerShell Core

pwsh.exe -NoLogo -ExecutionPolicy Bypass -Command "./Script.ps1 -Param1 Hello -Param2 World"

pwsh.exe -NoLogo -ExecutionPolicy Bypass -Command "path-to-script/Script.ps1 -Param1 Hello -Param2 World"

pwsh.exe -NoLogo -ExecutionPolicy Bypass -Command "./Script.ps1 Hello -Param2 World"

pwsh.exe -NoLogo -ExecutionPolicy Bypass -Command "./Script.ps1 Hello World"

pwsh.exe -NoLogo -ExecutionPolicy Bypass -Command "./Script.ps1 -Param2 World Hello"

PowerShell

powershell.exe -NoLogo -ExecutionPolicy Bypass -Command "./Script.ps1 -Param1 Hello -Param2 World"

powershell.exe -NoLogo -ExecutionPolicy Bypass -Command "path-to-script/Script.ps1 -Param1 Hello -Param2 World"

powershell.exe -NoLogo -ExecutionPolicy Bypass -Command "./Script.ps1 Hello -Param2 World"

powershell.exe -NoLogo -ExecutionPolicy Bypass -Command "./Script.ps1 Hello World"

powershell.exe -NoLogo -ExecutionPolicy Bypass -Command "./Script.ps1 -Param2 World Hello"

---

Call from PowerShell

PowerShell Core or Windows PowerShell

& path-to-script/Script.ps1 -Param1 Hello -Param2 World
& ./Script.ps1 -Param1 Hello -Param2 World

---

Script.ps1 - Script Code

param(
    [Parameter(Mandatory=$True, Position=0, ValueFromPipeline=$false)]
    [System.String]
    $Param1,

    [Parameter(Mandatory=$True, Position=1, ValueFromPipeline=$false)]
    [System.String]
    $Param2
)

Write-Host $Param1
Write-Host $Param2