c++ - 使用 QProcess 查询

Question

我应该检查服务是否RUNNING。我在执行以下查询时遇到了 QProcess 查询执行问题:SC QUERY "service name"| findstr RUNNING，尽管在​​ Windows 的命令行中直接执行时效果很好。这里的代码片段如下:

    QProcess process;
    process.setProcessChannelMode(QProcess::ForwardedChannels);
    process.start("SC QUERY \"Service_name\" | findstr RUNNING", QIODevice::ReadWrite);


    // Wait for it to start
    if(!process.waitForStarted())
        return 0;

    QByteArray buffer;
    while(process.waitForFinished())
        buffer.append(process.readAll());
    qDebug() << buffer.data();

输出是:

你能帮帮我吗？

Answer 1

这是因为使用这三行不会给你预期的结果:

QProcess process;
process.setProcessChannelMode(QProcess::ForwardedChannels);
process.start("SC QUERY \"Service_name\" | findstr RUNNING", QIODevice::ReadWrite);

基于official documentation ，QProcess 应该适用于管道命令:

void QProcess::setStandardOutputProcess(QProcess * destination)

Pipes the standard output stream of this process to the destination process' standard input.

换句话说，command1 | command2 shell command命令可以通过以下方式实现:

QProcess process1;
QProcess process2;

process1.setStandardOutputProcess(&process2);

process1.start("SC QUERY \"Service_name\"");
process2.start("findstr RUNNING");
process2.setProcessChannelMode(QProcess::ForwardedChannels);

// Wait for it to start
if(!process1.waitForStarted())
    return 0;

bool retval = false;
QByteArray buffer;
while ((retval = process2.waitForFinished()));
    buffer.append(process2.readAll());

if (!retval) {
    qDebug() << "Process 2 error:" << process2.errorString();
    return 1;
}

qDebug() << "Buffer data" << buffer;