Functions to instantly get, set, or delete an environment variable. Bypasses the typical delay experienced with Environment.SetEnvironmentVariable, which can be slow due to its broadcasting a message to all top-level windows. These functions offer a more efficient alternative for getting, setting, or deleting environment variables.

Set-EnvironmentVariable.ps1

# See this for more info:
# https://stackoverflow.com/questions/4825967/environment-setenvironmentvariable-takes-a-long-time-to-set-a-variable-at-user-o
function Set-EnvironmentVariable {
    <#
        .SYNOPSIS
        Instantly sets an environment variable in the machine or user environment by updating the registry.

        .DESCRIPTION
        Instantly sets an environment variable in the machine or user environment by updating the registry.

        .PARAMETER Name
        The name of the environment variable to set.

        .PARAMETER Value
        The value of the environment variable to set.

        .PARAMETER Target
        The target environment to set the environment variable in. Valid values are 'Machine' and 'User'.

        .EXAMPLE
        Set-EnvironmentVariable -Name "MyVariable" -Value "MyValue" -Target "Machine"
    #>
    [CmdletBinding()]
    param (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [string]$Name,

        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [string]$Value,

        [Parameter(Mandatory = $true)]
        [ValidateSet("Machine", "User")]
        [string]$Target
    )

    $regKey = switch ($Target.ToLower()) {
        "machine" { 'HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager\Environment' }
        "user" { 'HKCU:\Environment' }
    }

    Set-ItemProperty -Path $regKey -Name $Name -Value $Value
}

z-Get-EnvironmentVariable.ps1

function Get-EnvironmentVariable {
    <#
        .SYNOPSIS
        Retrieves the value of an environment variable from the machine or user environment by accessing the registry.

        .DESCRIPTION
        Retrieves the value of an environment variable from the machine or user environment by accessing the registry.

        .PARAMETER Name
        The name of the environment variable to retrieve.

        .PARAMETER Target
        The target environment to retrieve the environment variable from. Valid values are 'Machine' and 'User'.

        .EXAMPLE
        Get-EnvironmentVariable -Name "MyVariable" -Target "Machine"
    #>
    [CmdletBinding()]
    param (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [string]$Name,

        [Parameter(Mandatory = $true)]
        [ValidateSet("Machine", "User")]
        [string]$Target
    )

    $regKey = switch ($Target.ToLower()) {
        "machine" { 'HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager\Environment' }
        "user" { 'HKCU:\Environment' }
    }

    $existingProperties = Get-Item -Path $regKey | Select-Object -ExpandProperty Property

    if ($existingProperties -contains $Name) {
        $value = Get-ItemProperty -Path $regKey -Name $Name | Select-Object -ExpandProperty $Name
        return $value
    } else {
        Write-Warning "Environment variable '$Name' does not exist in the $Target environment."
        return $null
    }
}

z-Remove-EnvironmentVariable.ps1

function Remove-EnvironmentVariable {
    <#
        .SYNOPSIS
        Instantly removes an environment variable from the machine or user environment by updating the registry.

        .DESCRIPTION
        Instantly removes an environment variable from the machine or user environment by updating the registry.

        .PARAMETER Name
        The name of the environment variable to remove.

        .PARAMETER Target
        The target environment to remove the environment variable from. Valid values are 'Machine' and 'User'.

        .EXAMPLE
        Remove-EnvironmentVariable -Name "MyVariable" -Target "Machine"
    #>
    [CmdletBinding()]
    param (
        [Parameter(Mandatory = $true)]
        [ValidateNotNullOrEmpty()]
        [ValidateScript({
                if ($_.ToLower() -eq "path") {
                    throw "Cannot remove the 'Path' environment variable for safety reasons."
                }
                return $true
            })]
        [string]$Name,

        [Parameter(Mandatory = $true)]
        [ValidateSet("Machine", "User")]
        [string]$Target
    )

    $regKey = switch ($Target.ToLower()) {
        "machine" { 'HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager\Environment' }
        "user" { 'HKCU:\Environment' }
    }

    $existingProperties = Get-Item -Path $regKey | Select-Object -ExpandProperty Property

    if ($existingProperties -contains $Name) {
        # Write-Output "Removing environment variable '$Name' from the $Target environment."
        Remove-ItemProperty -Path $regKey -Name $Name
    } else {
        Write-Warning "Environment variable '$Name' does not exist in the $Target environment."
    }
}