Query with QProcess

Question

I'm supposed to check whether the service is RUNNING. I've a problem with QProcess query execution, when it comes to executing the following query: SC QUERY "service name" | findstr RUNNING, though this works fine when executed directly in command line in Windows. The code snipet here as follows:

    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();

Output is:

Can you help me?

Answer 1

It is because using these three lines will not give you the expected results:

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

Based on the official documentation, QProcess is supposed to work for pipe'd commands:

void QProcess::setStandardOutputProcess(QProcess * destination)

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

In other words, the command1 | command2 shell command command can be achieved in the following way:

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;