Retrieving python module path

Question

I want to detect whether module has changed. Now, using inotify is simple, you just need to know the directory you want to get notifications from.

How do I retrieve a module's path in python?

Answer 1

I will try tackling a few variations on this question as well:

1. finding the path of the called script
2. finding the path of the currently executing script
3. finding the directory of the called script

(Some of these questions have been asked on SO, but have been closed as duplicates and redirected here.)

Caveats of Using __file__

For a module that you have imported:

import something
something.__file__ 

will return the absolute path of the module. However, given the folowing script foo.py:

#foo.py
print '__file__', __file__

Calling it with 'python foo.py' Will return simply 'foo.py'. If you add a shebang:

#!/usr/bin/python 
#foo.py
print '__file__', __file__

and call it using ./foo.py, it will return './foo.py'. Calling it from a different directory, (eg put foo.py in directory bar), then calling either

python bar/foo.py

or adding a shebang and executing the file directly:

bar/foo.py

will return 'bar/foo.py' (the relative path).

Finding the directory

Now going from there to get the directory, os.path.dirname(__file__) can also be tricky. At least on my system, it returns an empty string if you call it from the same directory as the file. ex.

# foo.py
import os
print '__file__ is:', __file__
print 'os.path.dirname(__file__) is:', os.path.dirname(__file__)

will output:

__file__ is: foo.py
os.path.dirname(__file__) is: 

In other words, it returns an empty string, so this does not seem reliable if you want to use it for the current file (as opposed to the file of an imported module). To get around this, you can wrap it in a call to abspath:

# foo.py
import os
print 'os.path.abspath(__file__) is:', os.path.abspath(__file__)
print 'os.path.dirname(os.path.abspath(__file__)) is:', os.path.dirname(os.path.abspath(__file__))

which outputs something like:

os.path.abspath(__file__) is: /home/user/bar/foo.py
os.path.dirname(os.path.abspath(__file__)) is: /home/user/bar

Note that abspath() does NOT resolve symlinks. If you want to do this, use realpath() instead. For example, making a symlink file_import_testing_link pointing to file_import_testing.py, with the following content:

import os
print 'abspath(__file__)',os.path.abspath(__file__)
print 'realpath(__file__)',os.path.realpath(__file__)

executing will print absolute paths something like:

abspath(__file__) /home/user/file_test_link
realpath(__file__) /home/user/file_test.py

file_import_testing_link -> file_import_testing.py

Using inspect

@SummerBreeze mentions using the inspect module.

This seems to work well, and is quite concise, for imported modules:

import os
import inspect
print 'inspect.getfile(os) is:', inspect.getfile(os)

obediently returns the absolute path. However for finding the path of the currently executing script, I did not see a way to use it.

Answer 2

import os
path = os.path.abspath(__file__)
dir_path = os.path.dirname(path)

Answer 3

you can just import your module then hit its name and you'll get its full path

>>> import os
>>> os
<module 'os' from 'C:\\Users\\Hassan Ashraf\\AppData\\Local\\Programs\\Python\\Python36-32\\lib\\os.py'>
>>>

Answer 4

There is inspect module in python.

Official documentation

The inspect module provides several useful functions to help get information about live objects such as modules, classes, methods, functions, tracebacks, frame objects, and code objects. For example, it can help you examine the contents of a class, retrieve the source code of a method, extract and format the argument list for a function, or get all the information you need to display a detailed traceback.

Example:

>>> import os
>>> import inspect
>>> inspect.getfile(os)
'/usr/lib64/python2.7/os.pyc'
>>> inspect.getfile(inspect)
'/usr/lib64/python2.7/inspect.pyc'
>>> os.path.dirname(inspect.getfile(inspect))
'/usr/lib64/python2.7'

Answer 5

So I spent a fair amount of time trying to do this with py2exe The problem was to get the base folder of the script whether it was being run as a python script or as a py2exe executable. Also to have it work whether it was being run from the current folder, another folder or (this was the hardest) from the system's path.

Eventually I used this approach, using sys.frozen as an indicator of running in py2exe:

import os,sys
if hasattr(sys,'frozen'): # only when running in py2exe this exists
    base = sys.prefix
else: # otherwise this is a regular python script
    base = os.path.dirname(os.path.realpath(__file__))

Answer 6

import a_module
print a_module.__file__

Will actually give you the path to the .pyc file that was loaded, at least on Mac OS X. So I guess you can do

import os
path = os.path.dirname(amodule.__file__)

You can also try

path = os.path.abspath(amodule.__file__)

To get the directory to look for changes.