PowerShell: Automatic Variables

By Xah Lee. Date: . Last updated: .

PowerShell has many builtin variables, called automatic variables.

💡 TIP: Variable names are case-insensitive

Environment Related

Home Dir, Init File

$home

home dir env var. 

C:\Users\xah
$profile

full path of Profile (init file).

by default it is

~/Documents/PowerShell/Microsoft.PowerShell_profile.ps1

Note that even if this file does not exist, it still returns the path. To check if the file exists, use: test-path $profile.

PowerShell Info

$PsHome

full path of the installation directory for Windows PowerShell. 

C:\Program Files\WindowsApps\Microsoft.PowerShell_7.1.4.0_x64__8wekyb3d8bbwe
$host

a object that represents the current host application. Sample value: 

Name             : ConsoleHost
Version          : 7.1.4
InstanceId       :
UI               : System.Management.Automation.Internal.Host.InternalHostUserInterface
CurrentCulture   : en-US
CurrentUICulture : en-US
PrivateData      : Microsoft.PowerShell.ConsoleHost+ConsoleColorProxy
DebuggerEnabled  : True
IsRunspacePushed : False
Runspace         : System.Management.Automation.Runspaces.LocalRunspace
$PsVersionTable

A hash table object containing info about your PowerShell version. 

Name                           Value
----                           -----
PSVersion                      7.1.4
PSEdition                      Core
GitCommitId                    7.1.4
OS                             Microsoft Windows 10.0.19042
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Scripting Related

Standard Values

$true

The dotnet True. 〔see PowerShell: True, False (boolean)〕

$false

The dotnet False.

$null
  • Represents the dotnet Null.
  • Variable's default value is $null.

Arguments and Script Name

$_

The current object in a pipeline. 

dir -recurse | where {$_.length -eq 0}
$args

A Array of the argument received by Function or script or block of code.

$MyInvocation

value is the object that contains info of your script, function. 

# get the script path
$myinvocation.mycommand.path

# get the script name
$myinvocation.mycommand.name

# look at what members this object has
$myinvocation | get-member
$input

value is a enumerator object that contains the input that is passed to a function. The items in the enumerator are the objects in the current pipeline.

$pwd

value is a path object that represents the full path of the current dir.

Iterators; Misc

$ForEach

value is a enumerator object of the current ForEach-Object loop. This var exists only when a “for loop” is running. 〔see Loop, Iteration〕

$Matches

value is a hash table that represents matched text, from using the -match operator. 〔see PowerShell: Regular Expression Operators〕

Error

$?

value is True if last operation succeeded, else False.

$LastExitCode

value is the exit code of the last program.

$Error

value is a array of objects, representing the recent errors. $Error[0] is the most recent, $Error[1] is the error before that, etc.

Complete List of Automatic Variables

type help about_automatic_variable