Environment variables in PowerShell

Introduction

Environment variables store information that programs and scripts can use to work properly. They help scripts know about the system or user settings without hardcoding values.

You want to get the current user's home folder path in a script.

You need to check or set the system's PATH to run programs.

You want to store a secret key or configuration that your script can access.

You want to make your script work on different computers without changing code.

You want to temporarily change a setting for a program run by your script.

Syntax

PowerShell

Get-ChildItem Env:\
$env:VARIABLE_NAME = "value"
$env:VARIABLE_NAME

Use Get-ChildItem Env:\ to list all environment variables.

Use $env:VARIABLE_NAME to read or set an environment variable.

Examples

Lists all environment variables available in the current session.

PowerShell

Get-ChildItem Env:\

Shows the current user's name stored in the environment variable USERNAME.

PowerShell

$env:USERNAME

Sets a new environment variable MY_VAR to 'Hello' and prints it.

PowerShell

$env:MY_VAR = "Hello"
Write-Output $env:MY_VAR

Sample Program

This script sets a new environment variable GREETING, prints it, and then shows the current user and home path from existing environment variables.

PowerShell

$env:GREETING = "Hello, PowerShell!"
Write-Output "The greeting is: $env:GREETING"

# List a few important environment variables
Write-Output "User: $env:USERNAME"
Write-Output "Home Path: $env:HOMEPATH"

Important Notes

Environment variables set in a script only last for that session unless saved permanently.

Use $env:VARIABLE_NAME = $null to remove an environment variable in the current session.

Be careful not to overwrite important system environment variables.

Summary

Environment variables store system or user information accessible to scripts.

Use $env:VARIABLE_NAME to read or write environment variables in PowerShell.

They help make scripts flexible and adaptable to different environments.