修改Windows环境变量后不重新启动使之立即生效的方法_注册表修改环境变量后生效-优快云博客

本文介绍如何在Windows系统下通过编程修改环境变量，并确保修改立即生效的技术细节，包括修改当前进程、系统及用户环境变量的方法，以及发送全局广播通知以使更改立即生效的操作。

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想在Windows下通过编程修改环境变量的值，并且希望修改完后立即生效。
一、环境变量的修改
（1）修改当前进程的某个环境变量：SetEnvironmentVariable。
（2）修改系统环境变量：在注册表HKEY_LOCAL_MACHINESystemCurrentControlSetControlSession ManagerEnvironment中修改。
（3）修改用户环境变量：在注册表中HKEY_CURRENT_USEREnvironment修改。
二、环境变量的生效
在网上搜了一下，有两种说法：
（1）SendMessage(HWND_BROADCAST,WM_SETTINGCHANGE,0,(LPARAM)TEXT("Environment"));
（2）SendMessageTimeout(HWND_BROADCAST, WM_SETTINGCHANGE, 0,LPARAM("Environment"), SMTO_ABORTIFHUNG, 5000, &MsgResult);
没有尝试，先记在这儿。

很简单：

SendMessageTimeout(HWND_BROADCAST, WM_SETTINGCHANGE, 0,LPARAM("Environment"), SMTO_ABORTIFHUNG, 5000, &MsgResult);

发一个全局的广播，等待各自相应后，立即生效。

{ Note: We originally used SendNotifyMessage to broadcast the message but it
    turned out that while it worked fine on NT 4 and 2000 it didn't work on XP
    -- the string "Environment" in lParam would be garbled on the receiving
    end (why I'm not exactly sure). We now use SendMessageTimeout as directed
    in the KB article 104011. It isn't as elegant since it could cause us to
    be delayed if another app is hung, but it'll have to do. }