将命令行进程的标准输出重定向到文件

Posted 2023-02-16

【中文标题】将命令行进程的标准输出重定向到文件

【英文标题】：Redirecting Stdout of a commandline process to a file

【发布时间】：2013-08-30 10:41:48

【问题描述】：

我有一个 MFC 应用程序，它通过 CreateProcess 函数向 cmd 发送命令。我想将标准输出放入日志文件。代码是这样的

    void CMainFrame::OnCompile( CString cmd )
    
    CWaitCursor cursor;

    SECURITY_ATTRIBUTES sec;
    ZeroMemory( &sec, sizeof(sec) );
    sec.nLength = sizeof(SECURITY_ATTRIBUTES);
    sec.lpSecurityDescriptor = NULL;    
    sec.bInheritHandle = TRUE;

    HANDLE hstdoutf = CreateFile("e:\\user_stdout.txt",GENERIC_WRITE,FILE_SHARE_READ|FILE_SHARE_WRITE,&sec,CREATE_ALWAYS,FILE_ATTRIBUTE_NORMAL,NULL);

    STARTUPINFO siStartupInfo;
    PROCESS_INFORMATION piProcessInfo;
    memset(&siStartupInfo, 0, sizeof(siStartupInfo));
    memset(&piProcessInfo, 0, sizeof(piProcessInfo));
    siStartupInfo.cb = sizeof(siStartupInfo);
    siStartupInfo.dwFlags = STARTF_USESHOWWINDOW  ;
    siStartupInfo.wShowWindow = SW_HIDE; 




    if (hstdoutf!=INVALID_HANDLE_VALUE) 
        siStartupInfo.hStdOutput=hstdoutf;
    
    // Wait up to 100 seconds for the compilation process to finish
    if (!::CreateProcess(0, (char*)(cmd.GetString()), 0, 0, false,0, 0, 0,     
    &siStartupInfo, &piProcessInfo) ||
        (WaitForSingleObject(piProcessInfo.hProcess, 100000) != WAIT_OBJECT_0))
    
        MessageBox("Fail to execute command","Test",MB_ICONERROR);
    
    else
    
        CloseHandle(hstdoutf);
    

    

---

但代码运行不正常。仅创建一个空白文件。 我做错了什么？请帮忙。

【参考方案1】：

您忘记在 siStartupInfo.dwFlags 中指定 STARTF_USESTDHANDLES 标志。

改变

startupInfo.dwFlags = STARTF_USESHOWWINDOW  ;

到

startupInfo.dwFlags = STARTF_USESHOWWINDOW | STARTF_USESTDHANDLES ;

改变

CreateProcess(0, (char*)(cmd.GetString()), 0, 0, false, 0, 0, 0,
    &siStartupInfo, &piProcessInfo)

到

CreateProcess(0, (char*)(cmd.GetString()), 0, 0, true, 0, 0, 0,
    &siStartupInfo, &piProcessInfo)

我建议你阅读STARTUPINFO documentation 的STARTF_USESTDHANDLES 部分，有很多信息。

顺便说一句，您还应该添加

CloseProcess(piProcessInfo.hProcess)

在最后。