What is PYTHONPATH

Dec 4, 2023

The PYTHONPATH is a variable in Python that the interpreter uses to locate modules by searching through the paths specified in sys.path.

sys.path is a list that includes, in order

The directory of the script (if applicable).
Paths specified in the environmental variable PYTHONPATH.
Other paths depending on the Python installation on your system.

So, when you import a module, Python searches through these paths in order to find the module.

For example, on my system

>>> import sys
>>> sys.path
['', '/usr/lib/python36.zip', '/usr/lib/python3.6', '/usr/lib/python3.6/lib-dynload', 
'/usr/local/lib/python3.6/dist-packages', '/usr/lib/python3/dist-packages']

To view the value of PYTHONPATH

echo $PYTHONPATH

In Linux, you can add a new path to PYTHONPATH like this

export PYTHONPATH="$PYTHONPATH:/path/to/dir/"