how to use subprocess to execute an exe with args and an output

[MRAB]

On 2013-01-30 17:15, noydb wrote:
> I am looking for some guidance on using subprocess to execute an EXE with arguments and an output.  The below code works in that it returns a 0 exit code, but no output file is created.  I have tried a few different versions of this code (used Popen instead, some stderr/stdout), but no luck.  Can anyone offer an explanation or suggestion?  (GPSBabel is freeware)
> Python 2.7 on windows7 64-bit
>
> import subprocess
> subprocess.call([r"C:\Program Files (x86)\GPSBabel\gpsbabel.exe",
>                  "-i", "gdb", "-f", r"C:\Temp\GDBdata\testgps28.gdb",
>                  "-o", "gpx", r"C:\Temp\gpx\test28output.gpx"])
>
> If I use this below, I get a returncode of 1, exit code of 0.
> import subprocess
> x = subprocess.Popen([r"C:\Program Files (x86)\GPSBabel\gpsbabel.exe",
>                  "-i", "gdb", "-f", r"C:\Temp\GDBdata\testgps28.gdb",
>                  "-o", "gpx", r"C:\Temp\gpx\test28output.gpx",
>                  "shell=True", "stdout=subprocess.PIPE", "stderr=subprocess.PIPE"])
>
> x.wait()
> print x.returncode
>
> Thanks in advance for any help
>
The second example is incorrect. The parts starting from "shell" are
supposed to be further arguments for Popen itself, not something passed
to "gpsbabel.exe":

x = subprocess.Popen([r"C:\Program Files (x86)\GPSBabel\gpsbabel.exe",
                  "-i", "gdb", "-f", r"C:\Temp\GDBdata\testgps28.gdb",
                  "-o", "gpx", r"C:\Temp\gpx\test28output.gpx"],
                  shell=True, stdout=subprocess.PIPE,
                  stderr=subprocess.PIPE)