PowerShell Cheat Sheet

# Variables
$name = "Admin"
$age = 25
$isAdmin = $true

# Arrays
$ports = @(21, 22, 80, 443)
$ports[0]              # Access element
$ports += 8080         # Add element

# Hash tables
$user = @{
    Name = "Admin"
    Role = "Administrator"
}
$user["Name"]          # Access value

# Special variables
$PSVersionTable        # PowerShell version
$env:USERNAME          # Current username
$env:COMPUTERNAME      # Computer name
$PWD                   # Current directory

if ($age -gt 18) {
    Write-Host "Adult"
} elseif ($age -eq 18) {
    Write-Host "Just turned adult"
} else {
    Write-Host "Minor"
}

# Comparison operators: -eq, -ne, -gt, -lt, -ge, -le, -like, -match

# For loop
for ($i = 0; $i -lt 10; $i++) {
    Write-Host "Count: $i"
}

# ForEach loop
foreach ($port in $ports) {
    Write-Host "Port: $port"
}

# ForEach-Object (pipeline)
Get-Process | ForEach-Object {
    Write-Host $_.Name
}

# While loop
while ($count -lt 5) {
    Write-Host "Count: $count"
    $count++
}

# Basic function
function Get-Greeting {
    Write-Host "Hello World"
}

# Function with parameters
function Get-Sum {
    param(
        [int]$a,
        [int]$b
    )
    return $a + $b
}

# Advanced function with validation
function Test-Port {
    param(
        [Parameter(Mandatory=$true)]
        [string]$ComputerName,
        
        [Parameter(Mandatory=$true)]
        [int]$Port
    )
    
    try {
        $tcpClient = New-Object System.Net.Sockets.TcpClient
        $tcpClient.Connect($ComputerName, $Port)
        $tcpClient.Close()
        return $true
    } catch {
        return $false
    }
}