如何在Linux unsing QProcess下执行shell命令？

Question

我试图从Qt应用程序中读取屏幕分辨率,但不使用GUI模块.

所以我尝试过使用:

xrandr |grep \* |awk '{print $1}'

通过QProcess命令,但它显示警告并且不提供任何输出:

unknown escape sequence:'\\*'

重写它\\\*没有帮助,因为它会导致以下错误:

/usr/bin/xrandr: unrecognized option '|grep'\nTry '/usr/bin/xrandr --help' for more information.\n

我怎么解决这个问题？

Answer 1

你必须使用bash并在引号中传递参数:

#include <QCoreApplication>
#include <QProcess>
#include <QDebug>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QProcess process;
    QObject::connect(&process, &QProcess::readyReadStandardOutput, [&process](){
       qDebug()<<process.readAllStandardOutput();
    });
    QObject::connect(&process, &QProcess::readyReadStandardError, [&process](){
       qDebug()<<process.readAllStandardError();
    });
    process.start("/bin/bash -c \"xrandr |grep \\* |awk '{print $1}' \"");
    return a.exec();
}

输出:

"1366x768\n"

要么:

QProcess process;
process.start("/bin/bash", {"-c" , "xrandr |grep \\* |awk '{print $1}'"});

要么:

QProcess process;
QString command = R"(xrandr |grep \* |awk '{print $1}')";
process.start("/bin/sh", {"-c" , command});