sys.path vs. $PATH in Python

Question

In a Python program, I would like to access the $PATH variable. My understanding so far is that sys.path gives the Python module search path, but what I want is $PATH the environment variable. Is there a way to access that from within Python?

To give a little more background, what I ultimately want to do is find out where a user has Package_X/ installed so that I can find the absolute path of an HTML file in Package_X/.
If this is a bad practice or if there is a better way to accomplish this, I would appreciate any suggestions. Thanks!

What do you mean by "package"? Is it a python module? Or a distribution package for a specific distribution? Depending on what you are looking for, there may already be existing solutions. In the most general case, $PATH is probably not very helpful. — Leo Antunes
– Leo Antunes, Commented Aug 16, 2014 at 23:18
In setup.py, use data_files to install external files in a place where your Python package can find them. — tripleee
– tripleee, Commented Jul 10, 2022 at 7:32

tripleee · Accepted Answer · 2024-02-28 16:06:28Z

7

sys.path and PATH are two entirely different variables. The PATH environment variable specifies to your shell (or more precisely, the operating system's exec() family of system calls) where to look for binaries, whereas sys.path is a Python-internal variable which specifies where Python looks for installable modules.

The environment variable PYTHONPATH can be used to influence the value of sys.path if you set it before you start Python.

Conversely, os.environ['PATH'] can be used to examine the value of PATH from within Python (or any environment variable, really; just put its name inside the quotes instead of PATH).

edited Feb 28, 2024 at 16:06

answered Nov 10, 2020 at 11:43

tripleee

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1 Comment

tripleee Over a year ago

Perhaps see also stackoverflow.com/questions/1893598/pythonpath-vs-sys-path

Massimo Costa · Accepted Answer · 2014-08-16 23:13:05Z

4

you can read environment variables accessing to the os.environdictionary

import os

my_path = os.environ['PATH']

about searching where a Package is installed, it depends if is installed in PATH

answered Aug 16, 2014 at 23:13

Massimo Costa

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Comments

Yoel · Accepted Answer · 2014-08-16 23:33:11Z

0

To check whether a certain module is installed you can simply try importing it:

try:
    import someModule
except ImportError, e:
    pass # not installed

In order to check its path once its imported you can access its __path__ attribute via someModule.__path__:

Packages support one more special attribute, __path__. This is initialized to be a list containing the name of the directory holding the package’s __init__.py before the code in that file is executed.

Regarding access to environment variables from within Python, you can do the following:

import os
os.environ['PATH']

edited Aug 16, 2014 at 23:33

answered Aug 16, 2014 at 23:19

Yoel

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