# Find all commands with "Process" in the name
Get-Command -Name *Process*

# List all verbs
Get-Verb

# Get detailed help on a cmdlet
Get-Help Get-Process -Detailed

# See examples for a cmdlet
Get-Help Get-Service -Examples

# Named parameter
Get-Process -Name "notepad"

# Positional parameter (same as above)
Get-Process "notepad"

# Switch parameter (boolean flag)
Get-ChildItem -Recurse

# Multiple parameters
Get-EventLog -LogName "Application" -Newest 10

# Get processes → sort by memory → take top 5
Get-Process | Sort-Object -Property WorkingSet64 -Descending | Select-Object -First 5

# Get services → filter running ones → format as table
Get-Service | Where-Object { $_.Status -eq "Running" } | Format-Table Name, Status

# Get files → filter by extension → measure total size
Get-ChildItem -Path "C:\Logs" -Filter "*.log" |
  Measure-Object -Property Length -Sum

# String
$name = "Alice"

# Integer
$age = 30

# Boolean
$isAdmin = $true

# Array
$colors = "red", "green", "blue"
$colors = @("red", "green", "blue")  # explicit array syntax

# Hashtable (dictionary)
$user = @{
    Name  = "Alice"
    Age   = 30
    Admin = $true
}

# Access hashtable values
$user.Name          # "Alice"
$user["Age"]        # 30

# Check a variable's type
$name.GetType().Name  # String

[int]$count = "42"           # Converts string to int
[string]$text = 100          # Converts int to string
[datetime]$date = "2025-01-15" # Parses a date
[array]$list = "single"       # Forces single item into array

# AND — both must be true
(5 -gt 3) -and (10 -lt 20)   # True

# OR — at least one must be true
(5 -gt 10) -or (3 -eq 3)     # True

# NOT — negation
-not (5 -eq 3)                 # True
!(5 -eq 3)                     # True (shorthand)

$score = 85

if ($score -ge 90) {
    Write-Host "Grade: A"
} elseif ($score -ge 80) {
    Write-Host "Grade: B"
} elseif ($score -ge 70) {
    Write-Host "Grade: C"
} else {
    Write-Host "Grade: F"
}

$day = (Get-Date).DayOfWeek

switch ($day) {
    "Monday"    { Write-Host "Start of the week" }
    "Friday"    { Write-Host "Almost weekend!" }
    "Saturday"  { Write-Host "Weekend!" }
    "Sunday"    { Write-Host "Weekend!" }
    default     { Write-Host "Midweek grind" }
}

# For loop
for ($i = 0; $i -lt 5; $i++) {
    Write-Host "Iteration: $i"
}

# ForEach loop
$fruits = "apple", "banana", "cherry"
foreach ($fruit in $fruits) {
    Write-Host "I like $fruit"
}

# While loop
$count = 0
while ($count -lt 3) {
    Write-Host "Count: $count"
    $count++
}

# Do-While (runs at least once)
do {
    $input = Read-Host "Enter 'quit' to exit"
} while ($input -ne "quit")

# Pipeline ForEach
1..5 | ForEach-Object { $_ * 2 }  # Output: 2, 4, 6, 8, 10

function Get-Greeting {
    param(
        [string]$Name = "World"
    )
    return "Hello, $Name!"
}

Get-Greeting                   # "Hello, World!"
Get-Greeting -Name "Alice"     # "Hello, Alice!"

function Get-DiskSpace {
    [CmdletBinding()]
    param(
        [Parameter(Mandatory=$true)]
        [ValidateNotNullOrEmpty()]
        [string]$ComputerName,

        [ValidateSet("GB","MB","TB")]
        [string]$Unit = "GB"
    )

    begin   { Write-Verbose "Starting disk check..." }
    process {
        $divisor = switch ($Unit) {
            "TB" { 1TB }; "GB" { 1GB }; "MB" { 1MB }
        }
        Get-CimInstance Win32_LogicalDisk -ComputerName $ComputerName |
            Select-Object DeviceID,
                @{N="FreeSpace($Unit)"; E={[math]::Round($_.FreeSpace / $divisor, 2)}}
    }
    end     { Write-Verbose "Done." }
}

# Current location
Get-Location                    # alias: pwd

# Change directory
Set-Location "C:\Users"          # alias: cd

# List files and folders
Get-ChildItem                    # alias: ls, dir
Get-ChildItem -Recurse -Filter "*.log"

# List only directories
Get-ChildItem -Directory

# List hidden files too
Get-ChildItem -Force

# Create a directory
New-Item -Path "C:\Temp\Logs" -ItemType Directory

# Create a file
New-Item -Path "C:\Temp\notes.txt" -ItemType File

# Write content to file
Set-Content -Path "notes.txt" -Value "Line 1"
Add-Content -Path "notes.txt" -Value "Line 2"  # append

# Read content
Get-Content "notes.txt"

# Copy, move, rename, delete
Copy-Item "notes.txt" "backup.txt"
Move-Item "backup.txt" "C:\Archive\"
Rename-Item "notes.txt" "readme.txt"
Remove-Item "readme.txt"

# Does the path exist?
Test-Path "C:\Temp\notes.txt"   # True or False

# Get file details
Get-Item "C:\Temp\notes.txt" | Select-Object Name, Length, LastWriteTime

# Double quotes → variable expansion (interpolation)
$name = "Alice"
"Hello, $name!"                # "Hello, Alice!"
"2 + 2 = $(2 + 2)"            # "2 + 2 = 4" (subexpression)

# Single quotes → literal strings (no expansion)
'Hello, $name!'                # "Hello, $name!"

# Here-strings (multiline)
$multiline = @"
Line one
Line two with $name
"@

$text = "  Hello, World!  "

$text.Trim()                # "Hello, World!"
$text.ToUpper()              # "  HELLO, WORLD!  "
$text.ToLower()              # "  hello, world!  "
$text.Replace("World", "PS") # "  Hello, PS!  "
$text.Contains("World")      # True
$text.Split(",")             # ["  Hello", " World!  "]
$text.Substring(2, 5)       # "Hello"
$text.Length                 # 17

# String formatting
"Total: {0:C2}" -f 1234.5   # "Total: $1,234.50"

# -match returns true/false and fills $Matches
"Server-DC01" -match "Server-(\w+)"
$Matches[1]   # "DC01"

# -replace with regex
"2025-01-15" -replace "(\d{4})-(\d{2})-(\d{2})", '$3/$2/$1'
# "15/01/2025"

# Select-String (like grep)
Get-Content "server.log" | Select-String -Pattern "ERROR"

# Count matches
(Get-Content "server.log" | Select-String "ERROR").Count

# See all properties and methods of process objects
Get-Process | Get-Member

# See just properties
Get-Process | Get-Member -MemberType Property

# Access properties directly
(Get-Process "explorer").Id
(Get-Process "explorer").StartTime
(Get-Date).DayOfWeek

# PSCustomObject — the go-to way
$server = [PSCustomObject]@{
    Name     = "DC01"
    IP       = "192.168.1.10"
    OS       = "Windows Server 2022"
    Online   = $true
}

$server.Name       # "DC01"
$server | Format-List

# Array of custom objects
$inventory = @(
    [PSCustomObject]@{ Name="DC01"; Role="Domain Controller" }
    [PSCustomObject]@{ Name="WEB01"; Role="Web Server" }
    [PSCustomObject]@{ Name="DB01"; Role="Database" }
)

$inventory | Format-Table -AutoSize

# Add a calculated column to output
Get-Process | Select-Object Name, Id,
    @{Name="MemoryMB"; Expression={ [math]::Round($_.WorkingSet64 / 1MB, 2) }} |
    Sort-Object MemoryMB -Descending |
    Select-Object -First 10