在 Powershell 中设置后机器级环境变量不可用

Question

以下代码未按预期 return "Y"。只有在下一个会话（另一个新的window）它才有效？我希望它立即可用吗？

    [Environment]::SetEnvironmentVariable("X", "Y", "Machine")
    Write-Host $env:X

Answer 1

据我所知，一个进程只加载一次环境变量（在启动时）。但您可以使用以下方式更改它：

[Environment]::SetEnvironmentVariable("X", "Y", "Process") # for the current session

注意：您可能想同时设置两者：

[Environment]::SetEnvironmentVariable("X", "Y", "Machine")
[Environment]::SetEnvironmentVariable("X", "Y", "Process")

Answer 2

你必须这样做，因为进程在启动时获取环境变量，而不是在运行期间（即你必须重新启动 shell 才能按你的方式工作）：

 [Environment]::SetEnvironmentVariable("X", "Y", "Machine")
 $Env:X = "Y"

还有一种方法可以使用 WM_SETTINGCHANGE

将其广播给其他 windows

To effect a change in the environment variables for the system or the user, broadcast this message with lParam set to the string "Environment".)

# Notify system of change via WM_SETTINGCHANGE
    if (! ("Win32.NativeMethods" -as [Type]))
    {
        Add-Type -Namespace Win32 -Name NativeMethods -MemberDefinition @"
            [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
            public static extern IntPtr SendMessageTimeout( IntPtr hWnd, uint Msg, UIntPtr wParam, string lParam, uint fuFlags, uint uTimeout, out UIntPtr lpdwResult);
"@
    }

    $HWND_BROADCAST = [IntPtr] 0xffff; $WM_SETTINGCHANGE = 0x1a; $result = [UIntPtr]::Zero
    [Win32.Nativemethods]::SendMessageTimeout($HWND_BROADCAST, $WM_SETTINGCHANGE, [UIntPtr]::Zero, "Environment", 2, 5000, [ref] $result) | out-null
}

在 Powershell 中设置后机器级环境变量不可用

Machine level environment variable not available after setting in Powershell

powershell

environment-variables

powershell-4.0