Reusing the same QProcess variable in a loop

marlenet15

Is it possible to reuse the same QProcess variable more than once? The reason why I ask is because I would like to unmount several partitions from an external hard drive. Currently, if a USB is connected I am able to unmount it. However, if I have an external hard drive with more than one partition, it only unmounts the first partition it founds.

/* The command to check the USBs disk location is lsblk | grep USBNAME | awk '{print $1 }'
 * However, because this is a chain command, it is divided into 3 commands
 */
QProcess command1; //lsblk - all USB's information
QProcess command2; //grep USBname - info on specific USB
QProcess command3; //awk '{print $1 }' - grab just the USB name
QProcess command4; //unmount and detach USBs

QString disk;

//chain command
command1.setStandardOutputProcess(&command2);
command2.setStandardOutputProcess(&command3);
command3.setProcessChannelMode(QProcess::MergedChannels);

//get the disk names of all USBs connected
for(int j = 0; j < _USBlist.size(); j++)
{
    QStringList arg = QStringList()<<_USBlist[j];
    QStringList arg1 = QStringList()<<"{print $1 }";

    command1.start("lsblk");
    command2.start("grep",arg);
    command3.start("awk", arg1);

    command3.waitForFinished();
    QByteArray output = command3.readAll();

    QString outputTemp = QString(output);
    QString diskName = ""; //get diskname
    disk = "";  //get disk

    for(int i=0; i< outputTemp.size(); i++)
    {
        if(outputTemp.at(i).isLetter())
        {
            disk = disk + outputTemp.at(i);
            diskName = diskName + outputTemp.at(i);
        }
        else if(outputTemp.at(i).isNumber())
        {
        diskName = diskName + outputTemp.at(i);
        }
    }
    QStringList arg2 = QStringList()<<"--unmount" << "/dev/" + diskName;
    command4.start("udisks", arg2);
    command4.waitForFinished();

    arg.clear();
    arg1.clear();
    arg2.clear();

}
QStringList arg3 = QStringList()<<"--detach" << "/dev/" + disk;
command4.start("udisks", arg3);
command4.waitForFinished();

arg3.clear();
command1.close();
command2.close();
command3.close();
command4.close();

thebeast444

have you checked error(), errorString(), exitCode(), exitStatus() ?

I've run into somewhat similar problem.
In my program process runs fine the first time, but after that it keeps giving me "No such file or directory" and ProcessError::FailedToStart

marlenet15

@thebeast444 All I get is

"Unknown error"
QProcess::start: Process is already running

SGaist

Hi,

Maybe QEasyShell would make the whole process easier.

Lineaxe

Now QEasyShell sounds kewl :) I might find a place or two for something like that :)

marlenet15

I realized that the command was wrong and wasn't recognizing my partitions.