PowerShell Object pipeline shell

Version 7.6.7 · source

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Start here

Get-Help <cmd> -Examples

How do I use it?

Get-Command *<word>*

Find a command

<cmd> | Get-Member

What is in the output?

Get-ChildItem

List files

Where-Object <prop> -eq <val>

Filter objects

Select-Object <prop>, <prop>

Pick properties

Sort-Object <prop> -Descending

Sort objects

ConvertTo-Json

Objects to text

Concepts

Get-ChildItem file objects
Where-Object keep some
Sort-Object reorder
Select-Object shape
Format / Export text at the end

Objects flow through the pipeline; $_ is the current one

Discover

Get-Help <cmd>

Show help for a command

Add -Online for the web page, -Full for everything.

Get-Help <cmd> -Examples

Show usage examples

Get-Command *<word>*

Find commands by name

Get-Command -Verb <verb> -Noun <noun>

Find commands by verb or noun

<cmd> | Get-Member

List an object's type, properties, methods

Alias gm. The quickest way to learn what you can select.

Get-Alias <alias>

Show what an alias runs

Update-Help

Download help files

Help ships without full text; run once, often as admin.

Get-Help about_<topic>

Read a concept topic

e.g. about_Operators, about_Splatting.

Pipeline

Where-Object <prop> -gt <val>

Keep objects matching a test

Alias ? or where.

Where-Object { $_.Length -gt 1MB }

Filter with a script block

Select-Object <prop>, <prop>

Keep only these properties

Alias select.

Select-Object -First <n>

Take the first n objects

Select-Object -ExpandProperty <prop>

Output the bare values

Sort-Object <prop> -Descending

Sort by a property

ForEach-Object { $_.Name }

Run a block per object

Alias %. $_ and $PSItem are the same.

Group-Object <prop>

Group and count by value

Measure-Object <prop> -Sum -Average

Count, sum, average

Format-Table -AutoSize

Show as a table

Format-* is for display only: use it last.

Format-List *

Show every property

Out-File <file>

Write output to a file

Files & providers

Get-ChildItem

List items here

Aliases gci, dir; ls only on Windows.

Get-ChildItem -Recurse -Filter <glob>

Find files recursively

Set-Location <path>

Change directory

Alias cd. Push-Location / Pop-Location keep a stack.

Get-Content <file>

Read a file line by line

-Raw reads one string, -Tail <n> the end.

Set-Content <file> <text>

Overwrite a file

Add-Content <file> <text>

Append to a file

New-Item <dir> -ItemType Directory

Create a directory

Copy-Item <src> <dst> -Recurse

Copy files or folders

Move-Item <src> <dst>

Move or rename

Remove-Item <path> -Recurse -Force

Delete a tree

Add -WhatIf first to see what would go.

Test-Path <path>

Check if a path exists

Select-String <pattern> <file>

Search text, like grep

Regex by default; -SimpleMatch for literal text.

Get-PSDrive

List drives (FileSystem, Env, Variable)

Windows adds HKLM:, HKCU:, Cert:.

Variables & types

$name = <value>

Assign a variable

$env:<NAME>

Read or set an environment variable

$a = @(1, 2, 3)

Array; $a[-1] is the last item

+= copies the array; use a List for big loops.

$h = @{ Key = 'val' }

Hashtable; $h.Key or $h['Key']

[pscustomobject]@{ A = 1; B = 2 }

Build an object with properties

[int]$n = '42'

Cast or constrain a type

$null

Null; compare as $null -eq $x

Put $null on the left: on an array, -eq filters instead.

$PSVersionTable

Version and platform info

$x ?? <default>

Fallback if null (7+)

$cond ? <a> : <b>

Ternary operator (7+)

Strings & operators

"Hi $name, $($obj.Prop)"

Double quotes expand variables

Use $( ) for properties and expressions.

'literal $text'

Single quotes do not expand

`n `t `"

Escape with backtick

Backslash is a normal character.

@" ... "@

Here-string over several lines

Opening and closing markers on their own lines; @' '@ is literal.

-eq -ne -gt -lt -ge -le

Compare (case-insensitive)

-ceq etc. are case-sensitive. == and > do not compare.

-like '<glob>*'

Wildcard match

-match '<regex>'

Regex match; groups in $Matches

-replace '<regex>',
                    '<new>'

Regex replace

-split ',' / -join ','

Split or join strings

-contains / -in

Is the value in a collection

-and -or -not

Logical operators

<cmd1> && <cmd2>

Run next if success; || if failure (7+)

Data formats & web

Get-Content <file> -Raw | ConvertFrom-Json

Parse a JSON file

ConvertTo-Json -Depth <n>

Serialise objects to JSON

Default depth is 2; deeper levels are cut off with a warning.

Import-Csv <file>

Read CSV as objects

Export-Csv <file> -NoTypeInformation

Write objects as CSV

7+ omits the #TYPE line already; 5.1 needs the flag.

Invoke-RestMethod <url>

Call an API, parse the reply

Alias irm. JSON replies become objects.

Invoke-WebRequest <url> -OutFile <file>

Download a file

Alias iwr. curl is the real curl in 7 on all platforms.

Scripts & functions

function <Name> { param($x) ... }

Define a function

param([Parameter(Mandatory)] [string]$Name)

Required, typed parameter

param([switch]$Force, [int]$Count = 1)

Switch and default value

[CmdletBinding()]

Add common parameters like -Verbose

Put it above param() in a function or script.

.\<script>.ps1

Run a script

The .\ is required for the current folder.

. .\<script>.ps1

Dot-source: keep its functions

if (<cond>) { } elseif () { } else { }

Conditional

foreach ($i in $items) { }

Loop over a collection

switch ($x) { 'a' { } default { } }

Match a value against cases

-Wildcard and -Regex change the matching.

$PSScriptRoot

Folder of the running script

$p = @{ Path = '.' }; Get-ChildItem @p

Splat a hashtable as parameters

Errors

try { } catch { $_ } finally { }

Handle terminating errors

Most cmdlet errors are non-terminating: add -ErrorAction Stop.

-ErrorAction Stop

Make one command's errors catchable

Also SilentlyContinue, Ignore, Continue.

$ErrorActionPreference = 'Stop'

Stop on every error in scope

$Error[0]

Last error

Get-Error

Detailed view of the last error (7+)

throw '<message>'

Raise a terminating error

$LASTEXITCODE

Exit code of the last native program

$? is only true/false for the last command.

<cmd> -WhatIf

Preview what would change

Session & setup

$PROFILE

Path of your startup script

Create it with New-Item -Path $PROFILE -Force.

Get-ExecutionPolicy -List

Show script policies per scope

Set-ExecutionPolicy RemoteSigned -Scope CurrentUser

Allow local scripts (Windows)

Not enforced on Linux/macOS. Unblock-File clears the download mark.

Install-PSResource <module>

Install from PowerShell Gallery

7.4+. Older: Install-Module <name> -Scope CurrentUser.

Get-Process | Stop-Process

List or end processes

ForEach-Object -Parallel { } -ThrottleLimit <n>

Run blocks in parallel (7+)

pwsh -NoProfile -Command "<code>"

Run code from another shell

pwsh -File <script>.ps1

Run a script from another shell

PSReadLine keys

Tab / Shift+Tab

Cycle completions

Ctrl+Space

Menu of all completions

Windows mode (default on Windows); Linux/macOS use Emacs mode: Alt+= lists them.

Ctrl+R

Search history backwards

RightArrow

Accept the grey prediction

F2

Toggle inline / list predictions

Shift+Enter

Add a line without running

5.1 vs 7

What changed

	Windows PowerShell 5.1	PowerShell 7
Runs as	`powershell.exe`	`pwsh`
Platforms	`Windows`	`Windows, Linux, macOS`
Runtime	`.NET Framework`	`.NET (Core)`
File encoding	`mixed, often UTF-16`	`UTF-8 without BOM`
New syntax	`-`	`&& \|\| ?? ?: -Parallel`
Gone	`-`	`Get-WmiObject, workflows`

Recipes

Biggest files below here

Get-ChildItem -Recurse -File |  Sort-Object Length -Descending |  Select-Object -First 10 FullName,    @{ n = 'MB'; e = { [math]::Round($_.Length / 1MB, 1) } }

Edit JSON in place

$cfg = Get-Content app.json -Raw | ConvertFrom-Json$cfg.port = 8080$cfg | ConvertTo-Json -Depth 10 | Set-Content app.json

API to CSV

$url = 'https://api.github.com/repos/PowerShell/PowerShell/releases'Invoke-RestMethod $url |  Select-Object tag_name, published_at |  Export-Csv releases.csv -NoTypeInformation

Safe script skeleton

[CmdletBinding(SupportsShouldProcess)]param([Parameter(Mandatory)][string]$Path)$ErrorActionPreference = 'Stop'try {  Get-ChildItem $Path -Filter *.log |    Where-Object LastWriteTime -lt (Get-Date).AddDays(-30) |    Remove-Item   # -WhatIf works via SupportsShouldProcess} catch { Write-Error $_; exit 1 }