Permanently add a directory to PYTHONPATH?

On MacOS, Instead of giving path to a specific library. Giving full path to the root project folder in

~/.bash_profile 

made my day, for example:

export PYTHONPATH="${PYTHONPATH}:/Users/<myuser>/project_root_folder_path"

after this do:

source ~/.bash_profile

The script below works on all platforms as it's pure Python. It makes use of the pathlib Path, documented here https://docs.python.org/3/library/pathlib.html, to make it work cross-platform. You run it once, restart the kernel and that's it. Inspired by https://medium.com/@arnaud.bertrand/modifying-python-s-search-path-with-pth-files-2a41a4143574. In order to run it it requires administrator privileges since you modify some system files.

from pathlib import Path
to_add=Path(path_of_directory_to_add)
from sys import path

if str(to_add) not in path:
    minLen=999999
    for index,directory in enumerate(path):
        if 'site-packages' in directory and len(directory)<=minLen:
            minLen=len(directory)
            stpi=index
            
    pathSitePckgs=Path(path[stpi])
    with open(str(pathSitePckgs/'current_machine_paths.pth'),'w') as pth_file:
        pth_file.write(str(to_add))

This is an update to this thread which has some old answers.

For those using MAC-OS Catalina or some newer (>= 10.15), it was introduced a new Terminal named zsh (a substitute to the old bash).

I had some problems with the answers above due to this change, and I somewhat did a workaround by creating the file ~/.zshrc and pasting the file directory to the $PATH and $PYTHONPATH

So, first I did:

nano ~/.zshrc

When the editor opened I pasted the following content:

export PATH="${PATH}:/Users/caio.hc.oliveira/Library/Python/3.7/bin"
export PYTHONPATH="${PYTHONPATH}:/Users/caio.hc.oliveira/Library/Python/3.7/bin"

saved it, and restarted the terminal.

IMPORTANT: The path above is set to my computer's path, you would have to adapt it to your python.

The add a new path to PYTHONPATH is doing in manually by:

adding the path to your ~/.bashrc profile, in terminal by:

vim ~/.bashrc

paste the following to your profile

export PYTHONPATH="${PYTHONPATH}:/User/johndoe/pythonModule"

then, make sure to source your bashrc profile when ever you run your code in terminal:

source ~/.bashrc 

Hope this helps.

Fix Python Path issues when you switch from bash to zsh

I ran into Python Path problems when I switched to zsh from bash.

The solution was simple, but I failed to notice.

Pip was showing me, that the scripts blah blah or package blah blah is installed in ~/.local/bin which is not in path.

After reading some solutions to this question, I opened my .zshrc to find that the solution already existed.

I had to simply uncomment a line:

Take a look

Inspired by andrei-deusteanu answer, here is my version. This allows you to create a number of additional paths in your site-packages directory.

import os

# Add paths here.  Then Run this block of code once and restart kernel. Paths should now be set.
paths_of_directories_to_add = [r'C:\GIT\project1', r'C:\GIT\project2', r'C:\GIT\project3']

# Find your site-packages directory
pathSitePckgs = os.path.join(os.path.dirname(os.__file__), 'site-packages')

# Write a .pth file in your site-packages directory
pthFile = os.path.join(pathSitePckgs,'current_machine_paths.pth')
with open(pthFile,'w') as pth_file:
    pth_file.write('\n'.join(paths_of_directories_to_add))

print(pthFile)

I found a solution to do this in a anaconda environment here: https://datacomy.com/python/anaconda/add_folder_to_path/

Just:

conda develop /your_path

After multiple bashing into wall. Finally resolved, in my CentOS 8 the pip3 was old, which was showing error to install the recent packages.

Now, I had downloaded the Python source package, which is Python-3.10.4 and installed the usual way, however the post-installation check generated errors in bash.

And I could not remove the existing Python, because that would break the CentOS desktop features.

Solution:

For building

1. ./configure //don't not add --prefix=/usr, which you need to set proper care

2. make -j8

3. sudo make install

Now, as you have multiple Python installed, you can set alias python=python3

And for setting PYTHONPATH

export PYTHONPATH="/usr/local/bin/python3.10:/usr/local/lib/python3.10/lib-dynload:/usr/local/lib/python3.10/site-packages"

Don't add PYTHONHOME

For those who (like me) don't want to get too deeply involved in Python file management (which seems hopelessly overcomplicated), creating a .pth file works perfectly on my Windows 11 laptop (I'm using Visual Studio Code in Windows). So just go to the folder for your virtual environment site packages - there's mine:

Create a text file with a .pth extension - I called mine wheal.pth:

Add paths to it:

The best thing about this in VS Code is that import statements recognise this path (I had to exit VS Code and go back in), so now more typing # type: ignore to suppress linting warning messages!

on Mac :

user@terminal$ env PYTHONPATH=module_path python3
>>> import sys
>>> sys.path
['module_path', 'plus_other_python3_paths',...]

Shortest path between A <-> B is a straight line;

import sys
if not 'NEW_PATH' in sys.path:
  sys.path += ['NEW_PATH']