QString str = QString("echo %1 > /sys/class/backlight/*/brightness").arg(brightness);
int exitCore = QProcess::execute(str);
返回值 -2
QByteArray byteArray = str.toLatin1();
const char *command= byteArray.data();
qDebug() << "command:" << command;
int ret = system(command);
返回值 -1
怎么解决呢