Python error No such file or directory

Question

I get the following error: No such file or directory but I'm unsure why. I know it looks easy to explain but I'm unsure what directory its referring to here

env = os.environ.copy()
env['MY_LIB_PATH'] = '/Users/user/Documents/workspace/projecttest/lib'
subprocess.call(["test_program",image_url],env=env)

Error:

Traceback (most recent call last):
  File "test.py", line 20, in <module>
    model = get_model(image.get_image_content())
  File "/Users/user/Documents/workspace/projecttest/utilities.py", line 51, in get)model
    env=env
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 522, in call
    return Popen(*popenargs, **kwargs).wait()
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 709, in __init__
    errread, errwrite)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 1326, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory

What directory? It looks like the test program isn't there. Is it? — luk32
– luk32, Commented Aug 8, 2014 at 14:40
@MartijnPieters thanks for the reply. Would that relate to my environ? I get MY_LIB_PATH to point to the folder where they all are — Prometheus
– Prometheus, Commented Aug 8, 2014 at 14:42
Why do you think setting MY_LIB_PATH in the environment would have any effect on how subprocess looks for an executable? Where is test_program located? What's your working directory? — Wooble
– Wooble, Commented Aug 8, 2014 at 14:44

Roland Smith · Accepted Answer · 2014-08-08 15:03:46Z

3

To make sure that a program is found, you need to append to the PATH environment variable.

env = os.environ.copy()
env['PATH'] += os.pathsep + '/Users/user/Documents/workspace/projecttest/lib'
subprocess.call(["test_program", image_url], env=env)

Or you can call it explicitly;

cmd = '/Users/user/Documents/workspace/projecttest/lib/test_program'
subprocess.call([cmd, image_url])

Additionally, your test_program must be executable.

Note that subprocess.call can only execute programs. If you want to use a function from a dynamic link library, you'll have to use ctypes.

edited Aug 8, 2014 at 15:03

answered Aug 8, 2014 at 14:44

Roland Smith

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4 Comments

Raydel Miranda Over a year ago

In Windows is ';' no ':'.

Roland Smith Over a year ago

@RaydelMiranda From the paths it looks like Spike is running OS X.

Raydel Miranda Over a year ago

yes I know, I just want to point out that in Windows is different. Other user will read this in the future and there is no tag for an specific OS.

Roland Smith Over a year ago

@RaydelMiranda Changed it to use os.pathsep. That should work everywhere. Good point.

xbello · Accepted Answer · 2014-08-08 14:44:50Z

2

You cannot set a random environment variable and expect python to magically read it. Either you:

Insert the path in PATH.

Use your random environment variable to construct the path, e.g.:

subprocess.call([os.path.join(os.environ["MY_LIB_PATH"],
                              "test_program"),
                img_url])

answered Aug 8, 2014 at 14:44

xbello

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2 Comments

Prometheus Over a year ago

But does call() not allow you to set env=?

xbello Over a year ago

If you set MY_LIB_PATH, you can pass env to call as you say. Inside test_program you can retrieve os.environ["MY_LIB_PATH"].

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