Question

我使用以下代码来获取和设置环境变量。

public static string Get( string name, bool ExpandVariables=true ) {
    if ( ExpandVariables ) {
        return System.Environment.GetEnvironmentVariable( name );
    } else {
        return (string)Microsoft.Win32.Registry.LocalMachine.OpenSubKey( @"SYSTEM\CurrentControlSet\Control\Session Manager\Environment\" ).GetValue( name, "", Microsoft.Win32.RegistryValueOptions.DoNotExpandEnvironmentNames );
    }
}

public static void Set( string name, string value ) {
    System.Environment.SetEnvironmentVariable( name, value );
}

我面临的问题是，即使程序以管理员身份运行，只要程序运行，环境变量就会持续存在。我已经通过在上一个实例中设置的变量运行Get来确认了这一点。

上述

的使用示例

Set("OPENSSL_CONF", @"c:\openssl\openssl.cfg");

并检索

MessageBox.Show( Get("OPENSSL_CONF") );

在程序运行时，使用Set后，使用Get返回值，没有任何问题。问题是环境变量不是永久性的（在系统上设置）。

它也永远不会出现在高级属性下。

提前致谢。

Answer 1

程序运行时，使用Set后，返回值使用Get没有任何问题。问题是环境变量不是永久性的（在系统上设置）。

这是因为您在进程变量中使用存储的SetEnvironmentVariable超载。来自docs：

调用此方法相当于调用 SetEnvironmentVariable（String，String，EnvironmentVariableTarget）重载值为 EnvironmentVariableTarget.Process 的目标参数。

您需要使用指定EnvironmentVariableTarget.Machine的重载：

public static void Set(string name, string value) 
{
    Environment.SetEnvironmentVariable(name, value, EnvironmentVariableTarget.Machine);
}

Answer 2

根据MSDN，您使用的方法只是修改进程运行时的变量。

尝试此处描述的重载：https://msdn.microsoft.com/library/96xafkes%28v=vs.110%29.aspx

Answer 3

这类问题已被多次询问，请查看以下链接以获取更多信息：

formatter configuration

Set Env Variable - 1

Set Env Variable - 2

Answer 4

这是一个通过以编程方式编辑注册表来永久更新用户PATH变量的示例：

// Admin Permission not-required:
//      HKCU\Environment\Path
// Admin Permission required:
//      HKLM\SYSTEM\CurrentControlSet\Control
//         \Session Manager\Environment\Path

public static void UserPathAppend(string path, int verbose=1) {
    string oldpath = UserPathGet();

    List<string> newpathlist = oldpath.Split(';').ToList();
    newpathlist.Add(path);

    string newpath = String.Join(";", newpathlist.ToArray());

    UserPathSet(newpath);

    UpdateEnvPath();

    if (verbose!=0) {
        System.Windows.MessageBox.Show(
            "PATH APPEND:\n\n"
            + path + "\n\n"
            + "OLD HKCU PATH:\n\n"
            +  oldpath + "\n\n"
            + "NEW HKCU PATH:\n\n"
            +  newpath + "\n\n"
            + "REGISTRY KEY MODIFIED:\n\n"
            + "HKCU\\Environment\\Path\n\n"
            + "NOTE:\n\n"
            + "'Command Path' is a concat of 'HKLM Path' & 'HKCU Path'.\n",
            "Updated Current User Path Environment Variable"
        );
    }
}

public static void UserPathPrepend(string path, int verbose=1) {
    string oldpath = UserPathGet();

    List<string> newpathlist = oldpath.Split(';').ToList();
    newpathlist.Insert(0, path);

    string newpath = String.Join(";", newpathlist.ToArray());

    UserPathSet(newpath);

    UpdateEnvPath();

    if (verbose != 0) {
        System.Windows.MessageBox.Show(
            "PATH PREPEND:\n\n"
            + path + "\n\n"
            + "OLD HKCU PATH:\n\n"
            +  oldpath + "\n\n"
            + "NEW HKCU PATH:\n\n"
            +  newpath + "\n\n"
            + "REGISTRY KEY MODIFIED:\n\n"
            + "HKCU\\Environment\\Path\n\n"
            + "NOTE:\n\n"
            + "'Command Path' is a concat of 'HKLM Path' & 'HKCU Path'.\n",
            "Updated Current User Path Environment Variable"
        );
    }
}

public static string UserPathGet()
{
    // Reads Registry Path "HKCU\Environment\Path"
    string subKey = "Environment";

    Microsoft.Win32.RegistryKey sk = Microsoft.Win32.Registry.CurrentUser.OpenSubKey(subKey);

    if (sk == null)
        return null;
    else
        return sk.GetValue("Path").ToString();
}

public static void UserPathSet(string newpath)
{
    // Writes Registry Path "HKCU\Environment\Path"
    string subKey = "Environment";

    Microsoft.Win32.RegistryKey sk1 = Microsoft.Win32.Registry.CurrentUser.CreateSubKey(subKey);
    sk1.SetValue("Path", newpath);
}

//===========================================================
// Private: This part required if you don't want to logout 
//          and login again to see Path Variable update
//===========================================================

[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
private static extern IntPtr SendMessageTimeout(IntPtr hWnd, 
            uint Msg, UIntPtr wParam, string lParam, 
            SendMessageTimeoutFlags fuFlags, 
            uint uTimeout, out UIntPtr lpdwResult);

private enum SendMessageTimeoutFlags : uint
{
    SMTO_NORMAL = 0x0, SMTO_BLOCK = 0x1, 
    SMTO_ABORTIFHUNG = 0x2, SMTO_NOTIMEOUTIFNOTHUNG = 0x8
}

private static void UpdateEnvPath() {
    // SEE: https://support.microsoft.com/en-us/help/104011/how-to-propagate-environment-variables-to-the-system
    // Need to send WM_SETTINGCHANGE Message to 
    //    propagage changes to Path env from registry
    IntPtr HWND_BROADCAST = (IntPtr)0xffff;
    const UInt32 WM_SETTINGCHANGE = 0x001A;
    UIntPtr result;
    IntPtr settingResult
        = SendMessageTimeout(HWND_BROADCAST,
                             WM_SETTINGCHANGE, (UIntPtr)0,
                             "Environment",
                             SendMessageTimeoutFlags.SMTO_ABORTIFHUNG,
                             5000, out result);
}

如何在C＃中永久设置环境变量

4 个答案: