[Qt-interest] newbie:facing issues with readallstdoutput andQProcess

[john doe]

On Tue, May 5, 2009 at 1:48 AM, chandrasekar wagmare <sekarwagmare at gmail.com
> wrote:

>
> once i try to run an external system call glxgears in linux , i cant get
> the stdout in my qprocess and so one of the qt expert suggest me this ...
>   *"Most probably it's a problem of an incorrectly setup buffering
> method... and
> you won't be able to solve this from within your calling program.
> Either "patch" the program you are calling to use line buffering --
> setlinebuf(stdout) -- or use fflush(stdout) every now and then in this
> program. If you can't do this, then there's no way to solve it.
>
> It's NOT a problem of QProcess or anything you could solve by any trickery
> here... I have similar issues with some of the programs that I call from
> some
> of my apps and there's no way around it (at least no platform independent
> one).
>
> I've never tried this with glxgears, but an easy way to check if it is one
> of
> those programs which behave "incorrectl" would be to use "glxgears | less"
> for example. This is basically the same...
>
> (yes, just confirmed: it behaves exactly this way!)"*   i am not sure u
> are facing this problem but it might help you ...
>

awesome thanks!

>
>
> On Tue, May 5, 2009 at 12:13 AM, Will Rutherdale (rutherw) <
> rutherw at cisco.com> wrote:
>
>>  I’ve been testing QProcess on a Linux machine.  I have my Qt program run
>> a script that does output to a mix of STDERR and STDOUT.  The Qt program
>> connects to all the advertised signals in QProcess, and mostly works.
>>
>>
>>
>> I read the QProcess documentation and accordingly called
>> setProcessChannelMode( QProcess::MergedChannels ) before calling start().
>>
>>
>>
>> In my readyReadStandardOutput handler, I call readAllStandardOutput().
>> This is supposed to get all the output of the script from both STDOUT and
>> STDERR.  Unfortunately it only gets the output from STDERR.  The output from
>> STDOUT appears not to be available anywhere.  If I modify the script and
>> make all of its output go to STDERR, then the Qt program sees everything.
>>
>>
>>
>> Is this a known bug in QProcess?
>>
>>
>>
>> -Will
>>
>>
>>
>>
>>  ------------------------------
>>
>> *From:* qt-interest-bounces at trolltech.com [mailto:
>> qt-interest-bounces at trolltech.com] *On Behalf Of *john doe
>> *Sent:* 4 May 2009 13:20
>> *To:* Stephen Jackson
>> *Cc:* qt-interest at trolltech.com
>> *Subject:* Re: [Qt-interest] newbie:facing issues with readallstdoutput
>> andQProcess
>>
>>
>>
>>
>>
>> On Sun, May 3, 2009 at 11:44 PM, Stephen Jackson <spjackson42 at gmail.com>
>> wrote:
>>
>> On 04/05/09, john doe wrote:
>> >
>> > If I use program=python; and arguments << "version" or "-version" or
>> > "--version" no stdoutput or stderror is read back!
>> >  Can someone please help ?
>> >
>>
>> The code you posted only reads stdout, not stderr. If you run python
>> with the 3 different arguments you mention here, it writes to stderr
>> not stdout. If you want to read stderr, the QProcess documentation
>> explains how to do this.
>>
>>
>> Thanks for the answer :-), the problem is though if I try to run python
>> -h, I can see the output, but python --version won't work.!!!! I can't
>> figure out why a particular flag works and the other one does not!
>> [code]
>>
>>  program="python";
>>
>> arguments << "-V" ; //arguments << "--version"
>>
>> [/code]
>>
>> does not work
>>
>> [code]
>>
>> program="python";
>>
>> arguments << "-h" ;
>>
>> [/code]
>>
>> works!
>>
>>
>> Also, I want to run external programs and read their stdoutpout and
>> stderror. can I read in both into the same text box?
>>
>>
>>
>>
>> Regards,
>>
>> Stephen Jackson
>> _______________________________________________
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>> Qt-interest at trolltech.com
>> http://lists.trolltech.com/mailman/listinfo/qt-interest
>>
>>
>>
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>>
>
>
> --
> WAGMARE
>
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