可以通过在指定进程本身中覆盖环境表来实现这一点。

作为概念的证明，我写了这个示例应用程序，它只是在cmd.exe进程中编辑一个(已知的)环境变量:

typedef DWORD (__stdcall *NtQueryInformationProcessPtr)(HANDLE, DWORD, PVOID, ULONG, PULONG);

int __cdecl main(int argc, char* argv[])
{
    HMODULE hNtDll = GetModuleHandleA("ntdll.dll");
    NtQueryInformationProcessPtr NtQueryInformationProcess = (NtQueryInformationProcessPtr)GetProcAddress(hNtDll, "NtQueryInformationProcess");

    int processId = atoi(argv[1]);
    printf("Target PID: %u\n", processId);

    // open the process with read+write access
    HANDLE hProcess = OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION | PROCESS_VM_READ | PROCESS_VM_WRITE | PROCESS_VM_OPERATION, 0, processId);
    if(hProcess == NULL)
    {
        printf("Error opening process (%u)\n", GetLastError());
        return 0;
    }

    // find the location of the PEB
    PROCESS_BASIC_INFORMATION pbi = {0};
    NTSTATUS status = NtQueryInformationProcess(hProcess, ProcessBasicInformation, &pbi, sizeof(pbi), NULL);
    if(status != 0)
    {
        printf("Error ProcessBasicInformation (0x%8X)\n", status);
    }
    printf("PEB: %p\n", pbi.PebBaseAddress);

    // find the process parameters
    char *processParamsOffset = (char*)pbi.PebBaseAddress + 0x20; // hard coded offset for x64 apps
    char *processParameters = NULL;
    if(ReadProcessMemory(hProcess, processParamsOffset, &processParameters, sizeof(processParameters), NULL))
    {
        printf("UserProcessParameters: %p\n", processParameters);
    }
    else
    {
        printf("Error ReadProcessMemory (%u)\n", GetLastError());
    }

    // find the address to the environment table
    char *environmentOffset = processParameters + 0x80; // hard coded offset for x64 apps
    char *environment = NULL;
    ReadProcessMemory(hProcess, environmentOffset, &environment, sizeof(environment), NULL);
    printf("environment: %p\n", environment);

    // copy the environment table into our own memory for scanning
    wchar_t *localEnvBlock = new wchar_t[64*1024];
    ReadProcessMemory(hProcess, environment, localEnvBlock, sizeof(wchar_t)*64*1024, NULL);

    // find the variable to edit
    wchar_t *found = NULL;
    wchar_t *varOffset = localEnvBlock;
    while(varOffset < localEnvBlock + 64*1024)
    {
        if(varOffset[0] == '\0')
        {
            // we reached the end
            break;
        }
        if(wcsncmp(varOffset, L"ENVTEST=", 8) == 0)
        {
            found = varOffset;
            break;
        }
        varOffset += wcslen(varOffset)+1;
    }

    // check to see if we found one
    if(found)
    {
        size_t offset = (found - localEnvBlock) * sizeof(wchar_t);
        printf("Offset: %Iu\n", offset);

        // write a new version (if the size of the value changes then we have to rewrite the entire block)
        if(!WriteProcessMemory(hProcess, environment + offset, L"ENVTEST=def", 12*sizeof(wchar_t), NULL))
        {
            printf("Error WriteProcessMemory (%u)\n", GetLastError());
        }
    }

    // cleanup
    delete[] localEnvBlock;
    CloseHandle(hProcess);

    return 0;
}

样例输出:

>set ENVTEST=abc

>cppTest.exe 13796
Target PID: 13796
PEB: 000007FFFFFD3000
UserProcessParameters: 00000000004B2F30
environment: 000000000052E700
Offset: 1528

>set ENVTEST
ENVTEST=def

笔记

这种方法也仅限于安全限制。如果目标在更高的海拔或更高的帐户(如SYSTEM)上运行，那么我们将没有权限编辑它的内存。

如果你想对一个32位的应用程序这样做，上面的硬编码偏移量将分别更改为0x10和0x48。这些偏移量可以通过在调试器中转储_PEB和_RTL_USER_PROCESS_PARAMETERS结构体来找到(例如在WinDbg dt _PEB和dt _RTL_USER_PROCESS_PARAMETERS中)

要将概念证明更改为OP需要的内容，只需枚举当前系统和用户环境变量(如@tsadok的答案所记录的那样)，并将整个环境表写入目标进程的内存中。

Edit: The size of the environment block is also stored in the _RTL_USER_PROCESS_PARAMETERS struct, but the memory is allocated on the process' heap. So from an external process we wouldn't have the ability to resize it and make it larger. I played around with using VirtualAllocEx to allocate additional memory in the target process for the environment storage, and was able to set and read an entirely new table. Unfortunately any attempt to modify the environment from normal means will crash and burn as the address no longer points to the heap (it will crash in RtlSizeHeap).

环境变量保存在HKEY_LOCAL_MACHINE\SYSTEM\ControlSet\Control\Session Manager\Environment中。

许多有用的环境变量，如Path，都存储为REG_SZ。有几种方法可以访问注册表，包括REGEDIT:

REGEDIT /E <“HKEY_LOCAL_MACHINE \ SYSTEM \ ControlSet001 \会话管理器\ \控制环境”

输出从神奇的数字开始。因此，要用find命令搜索它，它需要输入并重定向:type <filename> | findstr -c:\"Path\"

所以，如果你只是想用系统属性刷新当前命令会话中的路径变量，下面的批处理脚本可以很好地工作:

RefreshPath.cmd:

    @echo off

    REM This solution requests elevation in order to read from the registry.

    if exist %temp%\env.reg del %temp%\env.reg /q /f

    REGEDIT /E %temp%\env.reg "HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Session Manager\Environment"

    if not exist %temp%\env.reg (
       echo "Unable to write registry to temp location"
       exit 1
       )

    SETLOCAL EnableDelayedExpansion

    for /f "tokens=1,2* delims==" %%i in ('type %temp%\env.reg ^| findstr -c:\"Path\"=') do (
       set upath=%%~j
       echo !upath:\\=\! >%temp%\newpath
       )

     ENDLOCAL

     for /f "tokens=*" %%i in (%temp%\newpath) do set path=%%i

我只是想说，那些使用Anaconda的人，当你使用chocoley Refreshenv命令时;所有与conda相关的环境变量都将丢失。 要解决这个问题，最好的方法是重新启动CMD。：(

这适用于windows 7: SET PATH=%PATH%

通过输入echo %PATH%测试，它工作正常。也设置如果你打开一个新的cmd，不需要那些讨厌的重新启动:)

使用“setx”并重新启动cmd提示符

有一个名为“setx”的命令行工具用于此作业。 它用于读取和写入env变量。 这些变量在命令窗口关闭后仍然存在。

创建或修改用户或系统环境中的环境变量，而不需要编程或脚本。setx命令还检索注册表项的值，并将它们写入文本文件。

注意:通过此工具创建或修改的变量将在以后的命令窗口中可用，但在当前CMD.exe命令窗口中不可用。所以，你必须重新开始。

如果缺少setx:

http://download.microsoft.com/download/win2000platform/setx/1.00.0.1/nt5/en-us/setx_setup.exe

或修改注册表

MSDN说:

若要以编程方式添加或修改系统环境变量，请使用add 他们去 HKEY_LOCAL_MACHINE \ System \ CurrentControlSet \ \控制会话 Manager\Environment注册表项，然后广播一个WM_SETTINGCHANGE 消息，lParam设置为字符串“环境”。 这允许应用程序(如shell)接收您的更新。

根据设计，Windows没有内置机制来将环境变量添加/更改/删除传播到已经运行的cmd.exe中，无论是从另一个cmd.exe还是从“我的电脑->属性->高级设置->环境变量”。

如果在现有的开放命令提示符范围之外修改或添加新的环境变量，则需要重新启动命令提示符，或者在现有的命令提示符中使用SET手动添加。

最新接受的答案通过手动刷新脚本中的所有环境变量显示了部分解决方案。该脚本处理在“My Computer…”中全局更改环境变量的用例。但是如果一个环境变量在一个cmd.exe中被更改，脚本不会将其传播到另一个运行cmd.exe的环境变量中。