CODEWITHSUNDEEP
pythonsubprocess
DieterDP
DieterDP

Reputation: 4377

Python subprocess cannot find programs

I am trying to call a java application from a python script. When Java was installed, a java.exe program was added to the c:\windows\system32 folder, this folder is included in the PATH environment variable.

Running

import subprocess
import os
subprocess.call("java") //or "c:/windows/system32/java.exe"

results in

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "c:\Program Files (x86)\Quantum GIS Lisboa\apps\Python27\Lib\subprocess.py", line 493, in call
    return Popen(*popenargs, **kwargs).wait()
  File "c:\Program Files (x86)\Quantum GIS Lisboa\apps\Python27\Lib\subprocess.py", line 679, in __init__
    errread, errwrite)
  File "c:\Program Files (x86)\Quantum GIS Lisboa\apps\Python27\Lib\subprocess.py", line 893, in _execute_child
    startupinfo)
WindowsError: [Error 2] Het systeem kan het opgegeven bestand niet vinden

Investigating a bit further, I tried running a console (cmd) using the same way. When doing a dir c:\windows\system32 in that console, java.exe is not listed! In fact, a whole bunch of files are not listed compared to running the same command from a "normal" console.

I have no clue what might be causing this, since the exact same workflow does work on another computer. I know I can circumvent the problem by directly calling the java installation, instead of the executable in the system32 folder, but I'd like to find the root of this problem.

This problem is occurring in a Quantum Gis plugin. Quantum Gis uses an included python installation, so I did not install python myself. The python version listed is "2.7.2 (default, Jun 12 2011, 15:08:59) [MSC v.1500 32 bit (Intel)] on Win32". I am running Windows 7 Professional.

Upvotes: 1

Views: 1214

Answers (1)

Martijn Pieters
Martijn Pieters

Reputation: 1124858

No, subprocess.call("java") can never result in a NameError being thrown.

You are running that without quotes instead:

>>> import subprocess
>>> subprocess.call(java)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'java' is not defined

A NameError exception is Python telling you the global name java is not defined in your code, not that the command java has not been found on your machine.

Upvotes: 4

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