Helpers/Get-EnvironmentVariable.ps1
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# Copyright © 2017 - 2021 Chocolatey Software, Inc. # Copyright © 2015 - 2017 RealDimensions Software, LLC # Copyright © 2011 - 2015 RealDimensions Software, LLC & original authors/contributors from https://github.com/chocolatey/chocolatey # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. function Get-EnvironmentVariable { <# .SYNOPSIS Gets an Environment Variable. .DESCRIPTION This will will get an environment variable based on the variable name and scope while accounting whether to expand the variable or not (e.g.: `%TEMP%`-> `C:\User\Username\AppData\Local\Temp`). .NOTES This helper reduces the number of lines one would have to write to get environment variables, mainly when not expanding the variables is a must. .PARAMETER Name The environment variable you want to get the value from. .PARAMETER Scope The environment variable target scope. This is `Process`, `User`, or `Machine`. .PARAMETER PreserveVariables A switch parameter stating whether you want to expand the variables or not. Defaults to false. Available in 0.9.10+. .PARAMETER IgnoredArguments Allows splatting with arguments that do not apply. Do not use directly. .EXAMPLE Get-EnvironmentVariable -Name 'TEMP' -Scope User -PreserveVariables .EXAMPLE Get-EnvironmentVariable -Name 'PATH' -Scope Machine .LINK Get-EnvironmentVariableNames .LINK Set-EnvironmentVariable #> [CmdletBinding()] [OutputType([string])] param( [Parameter(Mandatory = $true)][string] $Name, [Parameter(Mandatory = $true)][System.EnvironmentVariableTarget] $Scope, [Parameter(Mandatory = $false)][switch] $PreserveVariables = $false, [parameter(ValueFromRemainingArguments = $true)][Object[]] $ignoredArguments ) # Do not log function call, it may expose variable names ## Called from chocolateysetup.psm1 - wrap any Write-Host in try/catch [string] $MACHINE_ENVIRONMENT_REGISTRY_KEY_NAME = "SYSTEM\CurrentControlSet\Control\Session Manager\Environment\"; [Microsoft.Win32.RegistryKey] $win32RegistryKey = [Microsoft.Win32.Registry]::LocalMachine.OpenSubKey($MACHINE_ENVIRONMENT_REGISTRY_KEY_NAME) if ($Scope -eq [System.EnvironmentVariableTarget]::User) { [string] $USER_ENVIRONMENT_REGISTRY_KEY_NAME = "Environment"; [Microsoft.Win32.RegistryKey] $win32RegistryKey = [Microsoft.Win32.Registry]::CurrentUser.OpenSubKey($USER_ENVIRONMENT_REGISTRY_KEY_NAME) } elseif ($Scope -eq [System.EnvironmentVariableTarget]::Process) { return [Environment]::GetEnvironmentVariable($Name, $Scope) } [Microsoft.Win32.RegistryValueOptions] $registryValueOptions = [Microsoft.Win32.RegistryValueOptions]::None if ($PreserveVariables) { Write-Verbose "Choosing not to expand environment names" $registryValueOptions = [Microsoft.Win32.RegistryValueOptions]::DoNotExpandEnvironmentNames } [string] $environmentVariableValue = [string]::Empty try { #Write-Verbose "Getting environment variable $Name" if ($null -ne $win32RegistryKey) { # Some versions of Windows do not have HKCU:\Environment $environmentVariableValue = $win32RegistryKey.GetValue($Name, [string]::Empty, $registryValueOptions) } } catch { Write-Debug "Unable to retrieve the $Name environment variable. Details: $_" } finally { if ($null -ne $win32RegistryKey) { $win32RegistryKey.Close() } } if ($null -eq $environmentVariableValue -or $environmentVariableValue -eq '') { $environmentVariableValue = [Environment]::GetEnvironmentVariable($Name, $Scope) } return $environmentVariableValue } |