problem with System()
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Hello everyone:
First of all thanks a lot for reading this post and being able to help.
I have a problem whit System command.if I write:
sprintf(command, "%s %0.0f %0.0f 0 %0.0f %0.0f %s 0 0 +", princi,wps.front().x(), wps.front().y(),wps.back().x(),wps.back().y(),name_bmp); chdir("/home/"); //To change directory system(command);It give me segmentation fault when it runs system(command)
However if I write:
system("./princi 0 747.37 427.68 0 844.37 42.54 prueba_princi.bmp 0 0 +")it runs perfectly....
What am I doing wrong?
Thanks!wrote on 23 Jun 2016, 11:42 last edited by Joel BodenmannThis is not really an answer to your question but still related: You should consider using the QProcess class. This is not only a lot more flexible & portable than the
system()function but also integrates well into the Qt framework (signal&slots, properties, ...).
Usually you want to use Qt library components wherever possible.To still be somewhat useful: Did you check that
commandis large enough and that the string assembled bysprintf()is correct?Edit: @SGaist played ninja again....
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@AlvaroS said:
sprintf(command, "%s %0.0f %0.0f 0 %0.0f %0.0f %s 0 0 +", princi,wps.front().x(), wps.front().y(),wps.back().x(),wps.back().y(),name_bmp)
What types are
princi
name_bmpbetter not be QStrings :)
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@AlvaroS said:
sprintf(command, "%s %0.0f %0.0f 0 %0.0f %0.0f %s 0 0 +", princi,wps.front().x(), wps.front().y(),wps.back().x(),wps.back().y(),name_bmp)
What types are
princi
name_bmpbetter not be QStrings :)
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Then run your application through the debugger.
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wrote on 24 Jun 2016, 07:48 last edited by
@SGaist Now I do this:
QString program = "./home/princi"; QStringList arguments; arguments << "0" << QString::number(wps.front().x()) << QString::number(wps.front().y()) << "0" << QString::number(wps.back().x()) << QString::number(wps.back().y()) << "prueba_princi.bmp" << "0 0 +" ; QProcess myProcess; myProcess.start(program,arguments);it compiles good but my application does not run...
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You call it with a path relative to where you main application is started.
./home/princiis equivalent to$PWD/home/princi/which is likely not what you want, is it ? -
You call it with a path relative to where you main application is started.
./home/princiis equivalent to$PWD/home/princi/which is likely not what you want, is it ? -
You call it with a path relative to where you main application is started.
./home/princiis equivalent to$PWD/home/princi/which is likely not what you want, is it ?wrote on 24 Jun 2016, 07:58 last edited by@SGaist Now I do this and nothing as well..
QString program = "princi"; QStringList arguments; arguments << "0" << QString::number(wps.front().x()) << QString::number(wps.front().y()) << "0" << QString::number(wps.back().x()) << QString::number(wps.back().y()) << "prueba_princi.bmp" << "0 0 +" ; QString folder = "/home/"; QProcess *myProcess = new QProcess(this); myProcess->setWorkingDirectory(folder); myProcess->start(program,arguments); -
What is the full path to
princi? And what is the full path to your application ? -
/home is not the full path to your application except it is called home and is located in the root directory.
So, you can start the program in a shell with /home/princi?
Did you try it?
This is quite strange path: in /home you usually have a directory for each user and /home is not writable by normal user. -
/home is not the full path to your application except it is called home and is located in the root directory.
So, you can start the program in a shell with /home/princi?
Did you try it?
This is quite strange path: in /home you usually have a directory for each user and /home is not writable by normal user. -
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@AlvaroS So, if you enter /home/user1/princi in a terminal window and press enter it does not start? What happens? Any error message?
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Ok, you must debug then
try to use
http://doc.qt.io/qt-5/qprocess.html#error
to see what it thinks. -
@AlvaroS So, if you enter /home/user1/princi in a terminal window and press enter it does not start? What happens? Any error message?
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@jsulm In a terminal if I write
./princi 0 747.37 427.68 0 844.37 42.54 prueba_princi.bmp 0 0 +in /home/user1/ directory it runs good
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Ok, you must debug then
try to use
http://doc.qt.io/qt-5/qprocess.html#error
to see what it thinks.wrote on 24 Jun 2016, 08:38 last edited byThis post is deleted! -
@jsulm In a terminal if I write
./princi 0 747.37 427.68 0 844.37 42.54 prueba_princi.bmp 0 0 +in /home/user1/ directory it runs good
wrote on 24 Jun 2016, 08:39 last edited by AlvaroS
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