Permanently adding a file path to sys.path in Python
There are a few ways. One of the simplest is to create a my-paths.pth
file (as described here). This is just a file with the extension .pth
that you put into your system site-packages
directory. On each line of the file you put one directory name, so you can put a line in there with /path/to/the/
and it will add that directory to the path.
You could also use the PYTHONPATH environment variable, which is like the system PATH variable but contains directories that will be added to sys.path
. See the documentation.
Note that no matter what you do, sys.path
contains directories not files. You can't "add a file to sys.path
". You always add its directory and then you can import the file.
In one windows distribution in the following file:<python_root_installation_directory>/python38._pth
there are the following lines:
python38.zip../lib./lib/site-packages# Uncomment to run site.main() automatically#import site
Thus, with this content there the following yields:
Python 3.8.2 (tags/v3.8.2:7b3ab59, Feb 25 2020, 23:03:10) [MSC v.1916 64 bit (AMD64)] on win32>>> import sys>>> sys.path['C:\\Program Files\\Applications\\python_3_8_2\\python38.zip', 'C:\\Program Files\\Applications\\python_3_8_2', 'C:\\Program Files\\Applications\\python_3_8_2\\./lib', 'C:\\Program Files\\Applications\\python_3_8_2\\./lib/site-packages']
So After adding this line into the file: ./lib/site-packages/win32ctypes
it is present in the path:
Python 3.8.2 (tags/v3.8.2:7b3ab59, Feb 25 2020, 23:03:10) [MSC v.1916 64 bit (AMD64)] on win32>>> import sys>>> sys.path['C:\\Program Files\\Applications\\python_3_8_2\\python38.zip', 'C:\\Program Files\\Applications\\python_3_8_2', 'C:\\Program Files\\Applications\\python_3_8_2\\./lib', 'C:\\Program Files\\Applications\\python_3_8_2\\./lib/site-packages', 'C:\\Program Files\\Applications\\python_3_8_2\\./lib/site-packages/win32ctypes']
This way, you don't need to have PYTHONPATH
variable present on the system and you can still have the functionality. Disadvantage would be that this is installation specific, so if you have 3 different distributions on your system, this will affect only the chosen installation, while PYTHONPATH
will affect all of them simultaneously.