PowerShell Scripting Classroom Series – 30/Nov/2019

Understanding Powershell cmd-lets

• Cmdlets will always return objects.
• Every object will have
  • Methods
  • Properties
• Cmdlets are available by default in Powershell. Additional Cmdlets can be installed in the system using modules from Powershell Gallery.

Writing Scripts in Powershell

• Create a file with extension PS1
• To Start Scripting we need
  • DataTypes
  • Variables
  • Operators
• Preparation for Powershell Scripting
  • Powershell ISE
  • Visual Studio Code
• Visual Studio Code Preparation:
  • Install VS Code
  • Install Powershell Extension

Writing a Prime number is Powershell

$number = 99

$index = 2

$is_prime = $true
while ($index -lt $number) {
    if ($number % $index -eq 0) {
        $is_prime = $false
        break
    }

    $index += 1
    
}
if ($is_prime -eq $true) {
    echo "Prime"
}
else {
    echo "Not Prime"
}

Reading input from user

1. Read-Host:
   • Reads the input from user and type is always string
   • If you need other types, do the conversions.
   • For example refer code below

$enterednumber = Read-Host -Prompt 'Enter number'
$type = $enterednumber.GetType().FullName
echo "Number entered is $enterednumber and type is $type "
$number = [convert]::ToInt32($enterednumber)
$type = $number.GetType().FullName
echo "Number entered is $number and type is $type "

$index = 2

$is_prime = $true
while ($index -lt $number) {
    if ($number % $index -eq 0) {
        $is_prime = $false
        break
    }

    $index += 1
    
}
if ($is_prime -eq $true) {
    echo "Prime"
}
else {
    echo "Not Prime"
}

2. param:
   • Define parameters in PS1 file by using param block

param (
    [int32] $a,
    [int32] $b
)
$result = $a*$b
echo "$a * $b = $result"

* Calc.ps1 add/mul <numbers>

param(
    [Parameter(Mandatory=$true)]
    [string] $operation,
    [Parameter(Mandatory=$true)]
    [double] $num1,
    [Parameter(Mandatory=$true)]
    [double] $num2
)
if ($operation -eq 'add') {
    $result = $num1+$num2
    echo "$num1 + $num2 = $result"
}
elseif ($operation -eq 'mul') {
    $result = $num1*$num2
    echo "$num1 * $num2 = $result"
    
}
else {
    echo "$operation is not supported"
}

• Refer Here for parameters.

Environment Variables

• Environmental Variables in Powershell are much like other variables, but they have different syntax

$env:<variablename>

• To Get Environmental varaible

echo $env:Path

• To Set a new Environment variable

$env:test = "C:\"