The Ultimate PowerShell Cheatsheet

# ── Basic Cmdlets (Verb-Noun naming) ──
Get-Process                    # List processes
Get-Service                    # List services
Get-ChildItem -Path "C:\Temp"  # List directory contents
Get-Content -Path "file.txt"   # Read file contents
Get-Date                       # Current date/time
Get-History                    # Command history
Get-Alias grep                  # Find alias

# ── Filtering & Selection ──
Get-Process | Where-Object { $_.CPU -gt 10 }
Get-Process | Where-Object { $_.Name -like "*chrome*" }
Get-Process | Select-Object Name, CPU, WorkingSet -First 10
Get-Service | Where-Object Status -eq "Running"
Get-ChildItem -Filter "*.txt" -Recurse

# ── Sorting & Grouping ──
Get-Process | Sort-Object CPU -Descending
Get-Process | Group-Object -Property Name -NoElement
Get-ChildItem | Measure-Object -Property Length -Sum -Average

# ── Pipeline (| operator) ──
Get-Process | Where-Object {$_.WorkingSet -gt 100MB} |
    Sort-Object CPU -Descending |
    Select-Object Name, @{N="Memory(MB)";E={[math]::Round($_.WorkingSet/1MB)}} |
    Format-Table -AutoSize

# ── Common Verbs ──
# Get, Set, New, Remove, Add, Clear, Export, Import
# Start, Stop, Restart, Suspend, Resume
# Find, Search, Select, Sort, Group, Measure, Format, Out, Write

# ── Variables ──
$name = "John"
$age = 30
$isAdmin = $true
$pi = 3.14159
$null  # Null value
$empty = ""

# String interpolation
"Hello, $name!"                   # Double quotes: variables expanded
'Hello, $name'                    # Single quotes: literal
"Value: $(1 + 1)"                 # Subexpression: $(...)
"Today is $(Get-Date -Format 'yyyy-MM-dd')"

# Multi-line string
$heredoc = @"
Line 1
Line 2: $name is $age years old
"@

# ── Arrays ──
$fruits = @("apple", "banana", "cherry")
$numbers = 1..10
$empty = @()

$fruits[0]           # First item
$fruits[-1]          # Last item
$fruits.Count        # Length
$fruits += "date"    # Append
$fruits -contains "apple"

# ── Hashtables ──
$user = @{
    Name    = "John"
    Age     = 30
    Role    = "admin"
    Email   = "john@example.com"
}
$user["Name"]         # Access by key
$user.Name            # Dot notation
$user.Keys            # All keys
$user.Values          # All values

# ── PSCustomObject ──
$record = [PSCustomObject]@{
    Name       = "John"
    Department = "Engineering"
    Salary     = 85000
}
$record | Format-List

# ── Type Casting ──
[int]$num = "42"
[string]$str = 100
[bool]$flag = "true"
[int[]]$nums = @(1, 2, 3)

# ── Error Handling ──
try {
    $content = Get-Content -Path "/nonexistent/file.txt" -ErrorAction Stop
}
catch [System.Management.Automation.ItemNotFoundException] {
    Write-Host "File not found: $_" -ForegroundColor Red
}
catch {
    Write-Host "Unexpected error: $_" -ForegroundColor Red
}
finally {
    Write-Host "Cleanup complete" -ForegroundColor Green
}

# Error preference
$ErrorActionPreference = "Stop"       # Stop on error (default Continue)
$ErrorActionPreference = "SilentlyContinue"
$ErrorActionPreference = "Inquire"

# ── Functions ──
function Get-Greeting {
    param(
        [Parameter(Mandatory)]
        [string]$Name,

        [int]$Age = 0,

        [ValidateSet("Hello", "Hi", "Hey")]
        [string]$Greeting = "Hello"
    )
    "$Greeting, $Name! You are $Age years old."
}

Get-Greeting -Name "John" -Age 30 -Greeting "Hi"

# Pipeline function (process block)
function Get-FileSize {
    param([Parameter(ValueFromPipeline)]$Path)
    process {
        $item = Get-Item -Path $Path
        [PSCustomObject]@{
            File  = $item.Name
            Size  = $item.Length
            SizeKB = [math]::Round($item.Length / 1KB, 2)
        }
    }
}

Get-ChildItem "C:\Temp\*.txt" | Get-FileSize

# ── Modules ──
# List available modules
Get-Module -ListAvailable
Get-InstalledModule

# Install module (from PSGallery)
Install-Module -Name Pester -Scope CurrentUser
Install-Module -Name Az -Scope CurrentUser -Force

# Import module
Import-Module Pester

# Useful community modules
# Pester         → Testing framework
# Az             → Azure management
# dbatools      → SQL Server
# ImportExcel    → Excel files
# PSReadLine     → Better console