Setting Your PYTHONPATH environment variable (Linux/Unix/OsX)

Environment variables are lovely little shortcuts that your system uses to give many programs the ability to find certain shared resources easily.  In the *nix environments, these variables are set up for you when you log in to your terminal.  In order to customize these, you will need to modify a little shell script that runs every time you log in. In Linux/Unix this script is usually named something like “.bashrc” or “.bash_profile“, and Macs usually use “.profile” (note the preceding period).  These actually have slightly different purposes (one is for when you log in remotely, the other for log ins from the X-windowing system or some such).   The same process works for all file types, and most people rig them so that one always calls the other which means you only have to maintain one file.  If you have a Mac, just use .profile.

Open your file with a text editor.  You should see something like this:

PATH="${PATH}:/path/to/some/cool/package/:/path/to/another/cool/package/"
export PATH

PYTHONPATH="${PYTHONPATH}:/path/to/some/cool/python/package/:/path/to/another/cool/python/package/"
export PYTHONPATH

Along with some other stuff that we won’t go over today.  If you do not have a PYTHONPATH set up yet you can simply copy the one above (lines 4 AND 5) into your file and replace the useless paths that I include for paths to where your python packages live.

Some common places look like this:

# Linux
/usr/lib/python2.x/site-packages/

# Mac
/Library/Frameworks/Python.framework/Versions/2.x/lib/python2.x/site-packages/

You will want to look for where your system stores its python site-packages. You can also add any other folder that has python modules to this list of paths to allow them to be called by any python instance running in your shells.

These changes will not take effect until you start a new shell or reload the config file by running this on the command line:

source ~/.bashrc # or .bash_profile or .profile if you altered those