Difference between QProcess and exec()

[Markus]

All,

I need to call a shell script from within my Qt 4.7 (on Linux) app and QProcess is giving me trouble.
Here is the code that does not work - meaning it does execute the shell script but the environment is false:


QProcess myProcess(this);
myProcess->start(prog, args);

I tried setting "PATH" and some other env-variables via myProcess->setEnvironment() but with no effect. But this works fine:


pid_t pID = fork();
if (pID == 0)
execl(prog,prog,args, (char *) 0);

Any suggestion on what is going on?

Markus

[KShots]

Can you give an example of how you are setting the environment (what are you passing to QProcess::setEnvironment())?

What happens if you call:
myProcess->setEnvironment(QProcess::systemEnvironment())

Also, the QProcess::setEnvironment function was deprecated in Qt 4.6 in favor of the QProcess::setProcessEnvironment(const QProcessEnvironment & environment). It should still work, but the trolls claim the latter is more efficient.

[Markus]

I tried all variations of setting the environment but I does not make any difference.

[boudie]

Have you tried this:


QProcessEnvironment env = QProcessEnvironment::systemEnvironment();
env.insert("PATH", env.value("PATH") + ":" + settings->scriptsDirectory); // change this
...
scriptProcess->setProcessEnvironment(env);
scriptProcess->start(command, args);

[Markus]

I have a 1st clue, as soon as I start re-directing stdout my script fails. Code:


int my_pipe[2];
if(pipe(my_pipe) == -1)
{
fprintf(stderr, "Error creating pipe\n");
}

pid_t pID = fork();
if (pID == 0) // child
{
close(my_pipe[0]); // child doesn't read
dup2(my_pipe[1], 1); // redirect stdout
execl(prog,prog,args, (char *) 0);
}
I think the problem might most likely be in the script than in Qt