Catching an issue from external binary using grass Python Script

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Catching an issue from external binary using grass Python Script

Jenny Turner
Greetings

I have a Grass Python script that calls an external binary using subprocess like:
p=subprocess(<COMMAND>). Due to some limitations (memory) sometimes i get this copied into Command Output:
This application has requested the Runtime to terminate it
in an unusual way.
Please contact the application's support team for more
information.

(this is windows)

1- How can catch  this error (with except but I don't know which error to use

Thanks
Jenny


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Re: Catching an issue from external binary using grass Python Script

Glynn Clements

Jenny Turner wrote:

> I have a Grass Python script that calls an external binary using subprocess
> like:
> p=subprocess(<COMMAND>). Due to some limitations (memory) sometimes i get
> this copied into Command Output:
> This application has requested the Runtime to terminate it
> in an unusual way.
> Please contact the application's support team for more
> information.
>
> (this is windows)
>
> 1- How can catch  this error (with except but I don't know which error to
> use

"p=subprocess(<COMMAND>)" isn't valid Python; "subprocess" is a
module.

If you use subprocess.call(), the return value is the return code of
the child process.

If you use subprocess.Popen(), the .wait() method returns the child
process' return code, which can also be retrieved from the .returncode
attribute of the Popen object.

Typically, a return code of zero indicates success while a non-zero
value indicates failure. On Unix, a negative value indicates that the
process terminated due to a signal.

Neither call() nor Popen() raise an exception if the spawned program
"fails" in some sense, only if they are unable to execute the program,
query its status, etc.

--
Glynn Clements <[hidden email]>
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Re: Catching an issue from external binary using grass Python Script

Jenny Turner
You are absolutely right. I made a mistake. I meant p=subprocess.call(<COMMAND>)

If you use subprocess.call(), the return value is the return code of
the child process.

But In this case I obtain this in Command Output window:
> This application has requested the Runtime to terminate it
> in an unusual way.
> Please contact the application's support team for more
> information.
and my p is 3 (don't know why because in no place of the binary there is any return 3)
Is it possible to get above text ("This application ..." in a variable?
Thanks
Jenny
 
If you use subprocess.Popen(), the .wait() method returns the child
process' return code, which can also be retrieved from the .returncode
attribute of the Popen object.

Typically, a return code of zero indicates success while a non-zero
value indicates failure. On Unix, a negative value indicates that the
process terminated due to a signal.

Neither call() nor Popen() raise an exception if the spawned program
"fails" in some sense, only if they are unable to execute the program,
query its status, etc.

--
Glynn Clements <[hidden email]>


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Re: Catching an issue from external binary using grass Python Script

Glynn Clements

Jenny Turner wrote:

> *Is it possible to get above text ("This application ..." in a variable?*

If it's being written to stdout or stderr, you can capture those by
replacing subprocess.call() with:

        p = subprocess.Popen(<command>, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        out, err = p.communicate()

out and err will be strings, containing the data written to stdout and
stderr respectively.

--
Glynn Clements <[hidden email]>
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