How do I find out my python path using python?

The Question :

381 people think this question is useful

How do I find out which directories are listed in my system’s PYTHONPATH variable, from within a Python script (or the interactive shell)?

The Question Comments :
  • I’m not sure what are you trying to do, but if you want to know which folders are used to search for modules being imported you should not rely on PYTHONPATH. Use sys.path for that.
  • By simple experiment, I found Vanuan’s answer below (printing sys.path) just prints PYTHONPATH. This works after we alter the value using add_path(new_path) which adds to PYTHONPATH.
  • The title of this post and the body ask two different questions. sys.path is “A list of strings that specifies the search path for modules” – docs.python.org/2/library/sys.html#sys.path. PYTHONPATH is an environment variable that effects this list. By any reasonable definition sys.path is your “python path”.
  • Don’t forget about python -m site.

The Answer 1

248 people think this answer is useful

sys.path might include items that aren’t specifically in your PYTHONPATH environment variable. To query the variable directly, use:

import os
try:
    user_paths = os.environ['PYTHONPATH'].split(os.pathsep)
except KeyError:
    user_paths = []

The Answer 2

637 people think this answer is useful

You would probably also want this:

import sys
print(sys.path)

Or as a one liner from the terminal:

python -c "import sys; print('\n'.join(sys.path))"


Caveat: If you have multiple versions of Python installed you should use a corresponding command python2 or python3.

The Answer 3

11 people think this answer is useful

Can’t seem to edit the other answer. Has a minor error in that it is Windows-only. The more generic solution is to use os.sep as below:

sys.path might include items that aren’t specifically in your PYTHONPATH environment variable. To query the variable directly, use:

import os
os.environ['PYTHONPATH'].split(os.pathsep)

The Answer 4

4 people think this answer is useful

PYTHONPATH is an environment variable whose value is a list of directories. Once set, it is used by Python to search for imported modules, along with other std. and 3rd-party library directories listed in Python’s “sys.path”.

As any other environment variables, you can either export it in shell or in ~/.bashrc, see here. You can query os.environ[‘PYTHONPATH’] for its value in Python as shown below:

$ python3 -c "import os, sys; print(os.environ['PYTHONPATH']); print(sys.path) if 'PYTHONPATH' in sorted(os.environ) else print('PYTHONPATH is not defined')"

IF defined in shell as

$ export PYTHONPATH=$HOME/Documents/DjangoTutorial/mysite

THEN result =>

/home/Documents/DjangoTutorial/mysite
['', '/home/Documents/DjangoTutorial/mysite', '/usr/local/lib/python37.zip', '/usr/local/lib/python3.7', '/usr/local/lib/python3.7/lib-dynload', '/usr/local/lib/python3.7/site-packages']

ELSE result =>

PYTHONPATH is not defined

To set PYTHONPATH to multiple paths, see here.

Note that one can add or delete a search path via sys.path.insert(), del or remove() at run-time, but NOT through os.environ[]. Example:

>>> os.environ['PYTHONPATH']="$HOME/Documents/DjangoTutorial/mysite"
>>> 'PYTHONPATH' in sorted(os.environ)
True
>>> sys.path // but Not there
['', '/usr/local/lib/python37.zip', '/usr/local/lib/python3.7', '/usr/local/lib/python3.7/lib-dynload', '/usr/local/lib/python3.7/site-packages']

>>> sys.path.insert(0,os.environ['PYTHONPATH'])
>>> sys.path // It's there
['$HOME/Documents/DjangoTutorial/mysite', '', '/usr/local/lib/python37.zip', '/usr/local/lib/python3.7', '/usr/local/lib/python3.7/lib-dynload', '/usr/local/lib/python3.7/site-packages']
>>> 

In summary, PYTHONPATH is one way of specifying the Python search path(s) for imported modules in sys.path. You can also apply list operations directly to sys.path without the aid of PYTHONPATH.

The Answer 5

2 people think this answer is useful

Works in windows 10, essentially identical to vanuan’s answer, but cleaner (taken from somewhere, can’t remember where..):

import sys
for p in sys.path:
    print(p)

The Answer 6

1 people think this answer is useful

Python tells me where it lives when it gives me an error message 🙂

>>> import os
>>> os.environ['PYTHONPATH'].split(os.pathsep)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Users\martin\AppData\Local\Programs\Python\Python36-32\lib\os.py", line 669, in __getitem__
    raise KeyError(key) from None
KeyError: 'PYTHONPATH'
>>>

The Answer 7

0 people think this answer is useful

If using conda, you can get the env prefix using os.environ["CONDA_PREFIX"].

The Answer 8

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import sys
for a in sys.path:
    a.replace('\\\\','\\')
    print(a)

It will give all the paths ready for place in the Windows.

The Answer 9

0 people think this answer is useful
import subprocess
python_path = subprocess.check_output("which python", shell=True).strip()
python_path = python_path.decode('utf-8')

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