why qprocess not execute mount command correctly ?

[Christian Ehrlicher]

As always when you ask questions - please clarify, re-read your question and think if someone else could really understand what you're trying to ask.

My answer: No, noone understands your question...

[andr]

The 'mount <dev> <mountpoint>' version is usually run with root permissions. Do you have them?

[JonB]

@Qt-embedded-developer
I would be surprised if that is really the case. Show your QProcess code. Check for any errors, e.g. permissions as @andr has remarked.

[Qt embedded developer]

@andr @JonB yes i have given sudo permission using sudo visudo.

i have tested the code using system() it works fine but same thing is not working with qprocess

[Qt embedded developer]

@Christian-Ehrlicher

qprocess not execute below command correct way:

sudo mount /dev/sdb1 /mnt

what is right way to execute mount command using qprocess ?

i know how to use qprocess. so if possible let me know what argument argument i need to pass to make it correct ?

[JonB]

@Qt-embedded-developer said in why qprocess not execute mount command correctly ?:

i know how to use qprocess. so if possible let me know what argument argument i need to pass to make it correct ?

Then you won't mind showing your code for this, as requested? There is not somehow something "special", or a "special argument", because of using QProcess.
BTW this isn't going to work if your sudo requires a password.

[Qt embedded developer]

@JonB

QProcess OProcess;
  QString Command,sConnectedNodePath;

  Command = "sudo mount /dev/sdb1 /mnt ";


  OProcess.start(Command,QIODevice::ReadOnly);
  OProcess.waitForFinished();

  QString sCommandOutput = OProcess.readAllStandardOutput();
  QString StdError = OProcess.readAllStandardError();

  if(StdError.isEmpty())
  {
      qDebug() << "output : success";

}
else{
         qDebug() << "output : fail";
}

i got success output with not mounted directory at /mnt

[Axel Spoerl]

Can you qDebug() << sCommandOutput;as well?
What happens if you enter the command on the command line with the user who is running the executable? Pls share the command line output as well.

[JonB]

@Qt-embedded-developer

  QProcess OProcess;
  Command = "sudo mount /dev/sdb1 /mnt ";
  OProcess.start(Command,QIODevice::ReadOnly);

Show what overload of QProcess::start() (and what version of Qt) you think accepts a single string of sudo mount /dev/sdb1 /mnt as its first/program argument? I am not even sure which overload yours is using! Only QProcess::startCommand() accepts such a single-string command-line.

i got success output

What "success"? I see only a check as to whether StdError is empty. Which I would expect to be the case. And as @Axel-Spoerl asked, show sCommandOutput too, though I would expect that to be empty too. Plus please do confirm you have run this from the command line outside of Qt application, and its output.

Attach slots in yours to signals started/stateChanged/finished/errorOccurred() on your OProcess, and check return result of waitForFinished(), if you want to check its behaviour. Also exitStatus() & exitCode().

Also confirm whether or not your sudo requires a password anyway?

UPDATE
I see that at Qt 5.15 there was an obsoleted QProcess::start(const QString &command, QIODevice::OpenMode mode = ReadWrite), I guess that must be what you are using? You might still check the suggested slots, and show sCommandOutput too. OK, please confirm again about your sudo password as well, and we will take it from there....

[jsulm]

@Qt-embedded-developer said in why qprocess not execute mount command correctly ?:

Command = "sudo mount /dev/sdb1 /mnt ";

Please read the QProcess documentation: the parameters to the command are passed as a QStringList parameter to QProcess...

[JonB]

@jsulm
Like I discovered, I think OP must be using the obsoleted QProcess::start(const QString &command, QIODevice::OpenMode mode = ReadWrite). Assuming that is so, there must be a deeper reason why it fails to work, yet to be discovered from OP's future responses....