Hi everyone; I want to run the Linux command from qt code . I did following code to run the command but it is not executing my command. QString ab = "cd /sys/bus/iio/devices/iio:device1 && echo 24250000 > out_altvoltage1_TX_LO_frequency" QProcess p; p.startDetached("/bin/bash", QStringList()<<"-c"<<ab); Thanks in advance!

@ Wasee To answer your original question: the code you showed in your first example should do exactly what you say you want it to do --- provided you have first typed that command into a bash shell to verify it works correctly. So how do you know "it is not executing my command"? There is no need to run it startDetached() instead of plain start() . You could then capture any error and anything written to stdout/stderr ot check for anything unexpected. [Note: your literal string has \: in it. That is not right for C++. Either \\: or just simple : . Maybe that is why it had problems.] However, as @ jsulm said this command simple writes a string to a file. So no need for a QProcess , what is wrong with: QFile f("/sys/bus/iio/devices/iio:device1/out_altvoltage1_TX_LO_frequency"); if (f.open(QIODevice::WriteOnly)) { qint64 count = f.write("24250000"); Q_ASSERT(count > 0); f.close(); }

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How we can run Linux command from qt code?

Unsolved General and Desktop

21 Posts 4 Posters 2.5k Views

W Wasee
6 Jan 2022, 05:18
@JonB Thanks for your appreciated help!
Your suggestion of QFile is working fine now.
```
QFile f("/sys/bus/iio/devices/iio:device1/out_altvoltage1_TX_LO_frequency");
if (f.open(QIODevice::WriteOnly))
{
    qint64 count = f.write("2425000000");
    Q_ASSERT(count > 0);
    f.close();
}
```
The value 2425000000 is coming from a variable which can be change any time. I need to pass this value as a variable instead of constant 2425000000.
thanks
J Offline
J Offline
JonB

wrote on 6 Jan 2022, 08:18 last edited by

#21

@Wasee
You must convert your (integer) variable to a string. QIODevice::write() accepts either a const char * or a const QByteArray & for the string to write. You can use either QString::number() or QByteArray::number() to convert a number to a string/byte array to pass to write(), as you please.
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6 Jan 2022, 08:18