如何在c#中永久设置环境变量

本文关键字：设置 环境变量 | 更新日期: 2023-09-27 17:54:24

我使用下面的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，环境变量也只在程序运行期间存在。我通过对我在前一个实例中设置的变量运行Get来确认这一点。

以上

的示例用法
Set("OPENSSL_CONF", @"c:'openssl'openssl.cfg");

和检索

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

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)。

它也不会出现在高级属性下。

如何在c#中永久设置环境变量

程序运行时，使用Set后返回值使用Get没有任何问题。问题在于环境变量不是永久的(在系统上设置)。

那是因为你正在使用的SetEnvironmentVariable的过载存储在进程变量中。来自文档:

调用此方法相当于调用setenenvironmentvariable (String, String, EnvironmentVariableTarget)重载一个值为的EnvironmentVariableTarget。进程/blockquote>

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);
}

根据MSDN，您正在使用的方法只是修改进程运行时的变量。

尝试下面描述的重载:https://msdn.microsoft.com/library/96xafkes%28v=vs.110%29.aspx

这类问题已经被问过很多次了，点击以下链接获取更多信息:

设置环境变量- 1

设置环境变量- 2

设置环境变量-教程

下面是一个通过编程编辑注册表永久更新User 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);
}
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