PowerShell — Essential Commands Cheat Sheet

Help & Discovery#

Get-Command                          # List all commands
Get-Command *-Process                # Filter by name pattern
Get-Help Get-Process                 # Help for a command
Get-Help Get-Process -Examples       # Show examples
Get-Help Get-Process -Full           # Full documentation
Update-Help                          # Update local help database
Get-Member                           # Show object properties/methods
Get-Process | Get-Member             # Properties of Process objects

Navigation & File System#

Get-Location                         # pwd
Set-Location C:\Users\user\projects  # cd
Set-Location ~                       # Home directory
Push-Location C:\temp                # Push and cd
Pop-Location                         # Return to pushed location
Get-ChildItem                        # ls / dir
Get-ChildItem -Recurse -Filter *.log # Recursive filter
Get-ChildItem -File -Recurse | Where-Object { $_.Length -gt 1MB }

File Operations#

# Create
New-Item -ItemType File -Path file.txt
New-Item -ItemType Directory -Path mydir -Force

# Copy / Move
Copy-Item src.txt dest.txt
Copy-Item -Recurse ./src ./dest
Move-Item old.txt new.txt

# Delete
Remove-Item file.txt
Remove-Item -Recurse -Force ./dir

# Read / Write
Get-Content file.txt                 # cat
Get-Content file.txt | Select-Object -First 20   # head
Add-Content file.txt "new line"      # append
Set-Content file.txt "replace all"  # overwrite
$data = Get-Content file.txt         # store lines as array

Pipelines & Filtering#

# Pipeline basics
Get-Process | Where-Object { $_.CPU -gt 10 }
Get-Process | Sort-Object CPU -Descending | Select-Object -First 10
Get-Service | Where-Object { $_.Status -eq 'Running' }

# Select properties
Get-Process | Select-Object Name, CPU, WorkingSet
Get-Process | Select-Object -ExpandProperty Name   # just values

# Format output
Get-Process | Format-Table Name, CPU, Id
Get-Process | Format-List *           # all properties as list
Get-Process | Out-GridView            # interactive GUI grid (Windows)

# Export
Get-Process | Export-Csv processes.csv -NoTypeInformation
Get-Process | ConvertTo-Json | Out-File processes.json
Import-Csv data.csv

Variables & Data Types#

$name = "Alice"
$num = 42
$pi = 3.14
$flag = $true

# Arrays
$arr = @(1, 2, 3, "four")
$arr += 5
$arr[0]                              # first element
$arr[-1]                             # last element
$arr.Count                           # length

# Hashtables (dictionaries)
$hash = @{ name = "Alice"; age = 30 }
$hash["name"]                        # access
$hash.name                           # dot notation
$hash.Keys
$hash.Values
$hash.Remove("age")

# String interpolation
"Hello, $name!"                      # simple
"Result: $($num * 2)"               # expression in string

Conditionals & Loops#

# if / elseif / else
if ($x -gt 10) { "big" }
elseif ($x -eq 10) { "ten" }
else { "small" }

# Comparison operators
-eq  -ne  -gt  -lt  -ge  -le   # numbers
-like  -notlike                 # wildcards: "*.txt"
-match  -notmatch               # regex
-contains  -notcontains         # array membership

# for / foreach
for ($i = 0; $i -lt 10; $i++) { Write-Host $i }
foreach ($item in $arr) { Write-Host $item }
1..10 | ForEach-Object { Write-Host $_ }

# while
$i = 0
while ($i -lt 5) { Write-Host $i; $i++ }

Functions#

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

Get-Greeting -Name "Alice"              # Hello, Alice!
Get-Greeting -Name "Bob" -Greeting "Hi" # Hi, Bob!

Error Handling#

# Try / Catch / Finally
try {
  Get-Content "nonexistent.txt" -ErrorAction Stop
} catch [System.IO.FileNotFoundException] {
  Write-Error "File not found: $_"
} catch {
  Write-Error "Unexpected error: $_"
} finally {
  Write-Host "Cleanup here"
}

# Error preference
$ErrorActionPreference = "Stop"    # throw on any error
$ErrorActionPreference = "Continue"  # default

# Suppress errors
Get-Item "missing.txt" -ErrorAction SilentlyContinue

Remoting & Execution#

# Run command on remote machine
Invoke-Command -ComputerName server01 -ScriptBlock { Get-Process }

# Interactive session
Enter-PSSession -ComputerName server01

# Run script
Invoke-Command -ComputerName server01 -FilePath .\script.ps1

# Execution policy
Get-ExecutionPolicy
Set-ExecutionPolicy RemoteSigned    # Allow local + signed remote scripts
Set-ExecutionPolicy Bypass -Scope Process  # Just for current session

String Manipulation#

$s = "  Hello World  "
$s.Trim()                      # "Hello World"
$s.ToLower()                   # "  hello world  "
$s.ToUpper()                   # "  HELLO WORLD  "
$s.Replace("World", "PS")      # "  Hello PS  "
$s.Split(" ")                  # array of words
$s.Contains("World")           # True
$s.StartsWith("  Hello")       # True
$s.Substring(2, 5)             # "Hello"
$s -match "Hello\s(\w+)"       # regex match; $Matches[1] = "World"
-join ("a", "b", "c")          # "abc"
"a","b","c" -join "-"          # "a-b-c"

Useful Patterns#

# Measure execution time
Measure-Command { Start-Sleep -Seconds 2 }

# Find processes by name
Get-Process -Name *chrome* | Stop-Process -WhatIf

# Check if running as admin
([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)

# Load a module
Import-Module Az
Get-Module -ListAvailable Az*

# Environment variables
$env:PATH
$env:USERNAME
[System.Environment]::GetEnvironmentVariable("PATH", "Machine")
[System.Environment]::SetEnvironmentVariable("MY_VAR", "value", "User")

# Base64
$encoded = [Convert]::ToBase64String([Text.Encoding]::UTF8.GetBytes("hello"))
$decoded = [Text.Encoding]::UTF8.GetString([Convert]::FromBase64String($encoded))

Key Aliases#