PowerShell basics

PowerShell is Microsoft's shell and scripting language. It pipes .NET objects rather than text, which gives it a different grain from the bash family.

1. About PowerShell

PowerShell first shipped in 2006 as Windows PowerShell 1.0. It is a shell that runs on top of the .NET framework, where commands (cmdlets) take and emit objects rather than text. It came out of a system administration and automation lineage.

2. Two branches of PowerShell

Item	Windows PowerShell 5.1	PowerShell 7+
Runtime	.NET Framework	.NET Core / .NET 5+
Platform	Windows only	Windows · macOS · Linux
Default encoding	UTF-16 LE (BOM)	UTF-8 (no BOM)
&& · `		` pipeline chain
Ternary ? :	Not supported	Supported
Executable	powershell.exe	pwsh
Support	Bundled with Windows; security patches only	Active development

5.1 is shipped with Windows 10/11 and is not going away. 7+ requires a separate install (winget install Microsoft.PowerShell or brew install powershell on macOS).

3. cmdlet naming convention

cmdlets follow Verb-Noun.

Verb	Meaning
Get-	Read (Get-Process, Get-ChildItem).
Set-	Modify (Set-Location, Set-Content).
New-	Create (New-Item, New-Object).
Remove-	Delete (Remove-Item).
Start- · Stop-	Start/stop.
Invoke-	Invoke (Invoke-WebRequest, Invoke-RestMethod).

The approved verb list comes from Get-Verb. Consistent naming helps autocomplete and learning.

4. Aliases

Alias	Real name
ls · dir · gci	Get-ChildItem
cd · sl	Set-Location
cat · gc	Get-Content
cp · copy	Copy-Item
mv · move	Move-Item
rm · del	Remove-Item
pwd	Get-Location
cls	Clear-Host

Inside scripts the real name is preferred for readability (PSScriptAnalyzer's AvoidUsingCmdletAliases).

5. .ps1 and execution policy

.ps1 is the PowerShell script extension. For safety the default execution policy is Restricted, so a freshly downloaded script will not run right away.

Policy	Behavior
Restricted	Blocked (default).
AllSigned	Only signed scripts.
RemoteSigned	Scripts from the internet need a signature, local scripts run freely.
Unrestricted	Internet scripts run after a warning.
Bypass	Everything passes (CI, etc.).

Get-ExecutionPolicy
Set-ExecutionPolicy -Scope CurrentUser RemoteSigned

-Scope CurrentUser applies only to the current user, no admin rights needed.

6. Object pipes

Where bash pipes carry text, PowerShell pipes carry objects:

# bash
ps -ef | grep node | awk '{print $2}'

# PowerShell
Get-Process | Where-Object { $_.Name -eq "node" } | Select-Object -ExpandProperty Id

PowerShell accesses object properties directly, so awk-style text parsing is unnecessary. On the other hand, output from external commands (git, curl) arrives as strings, so text parsing comes back into play there.

7. bash equivalents

Task	bash	PowerShell
Directory listing	ls -la	Get-ChildItem -Force
Current location	pwd	Get-Location (pwd)
Clear screen	clear	Clear-Host (cls)
View file	cat file	Get-Content file
Find file	find . -name "*.md"	Get-ChildItem -Recurse -Filter *.md
Search content	grep -r "TODO" .	Select-String -Path *.* -Pattern "TODO"
Read env var	echo $PATH	$env:PATH
Set env var	export FOO=bar	$env:FOO = "bar"
HTTP request	curl ...	Invoke-WebRequest ...
Chain on success	a && b	a; if ($?) { b } (5.1) / a && b (7+)
Exit code	$?	$LASTEXITCODE (external exe) / $? (cmdlet)

8. Encoding traps (5.1)

Windows PowerShell 5.1 defaults Out-File, Set-Content, and > redirection to UTF-16 LE (with BOM). When other tools expect UTF-8 the resulting file is broken.

# Safe pattern under 5.1
"hello" | Out-File -Encoding utf8 file.txt
Set-Content -Encoding utf8 -Path file.txt -Value "hello"

PowerShell 7+ defaults to UTF-8 (no BOM).

9. Basic syntax

$name = "world"
Write-Output "hello, $name"

if (Test-Path "config.json") {
  Write-Output "found"
} else {
  Write-Output "missing"
}

foreach ($f in Get-ChildItem -Filter *.txt) {
  Write-Output $f.Name
}

function Greet {
  param([string]$Name)
  "hello, $Name"
}
Greet -Name "alice"

10. Common pitfalls

5.1 has no && / || — chains have to be unrolled into ; if ($?) { ... }.

Redirecting an external exe's stderr with 2>&1 under 5.1 wraps it in an ErrorRecord, so $? becomes $false. Leave stderr alone where possible.

Carelessly applying Set-ExecutionPolicy Bypass -Scope Process system-wide — restrict it with -Scope Process or -Scope CurrentUser.

Output stays in UTF-16 LE so other tools (Node, Python) cannot read it — pass -Encoding utf8 explicitly.

cmdlet names are case-insensitive and feel familiar, but relying on aliases when piping output to external tools can produce subtle compatibility issues.

Closing thoughts

Object pipes, Verb-Noun naming, and the strong cmdlet library are PowerShell's draws. The 5.1-era encoding, missing &&, and execution policy form the initial learning cost. The fact that 7+ is cross-platform and stands next to bash points at the future shape.

Next

• cmd-and-bat
• cross-platform-scripts

Microsoft PowerShell docs · about_Execution_Policies · about_Pipelines · PowerShell on GitHub · PSScriptAnalyzer for reference.