setting python search path in config file without environment variables (i.e. PYTHONPATH)

Question

Is there some way to set python's search path in a config file without setting PYTHONPATH, i.e. some default configuration file that python reads when it starts?

Answer 1

You have two options:

• List additional paths in a .pth file in one of the standard locations (usually your site-packages location). See How to add a Python import path using a .pth file as well.

• Add additional paths to sys.path in sitecustomize or usercustomize modules (detailed in the site module documentation). Your sitecustomize or usercustomize could look something like:

  import sys
  sys.path[0:0] = [
      '/foo/bar',
      '/spam/eggs',
  ]
  

  where the two extra entries would be inserted into sys.path at the front.

  You can also call site.addsitedir with a path in such a module, which will add that path to sys.path and process any .pth files found there.

Answer 2

To avoid messing with Python's system installation you could list the paths in .pth files that are in your USER_SITE directory e.g., ~/.local/lib/python2.7/site-packages. You could also put usercustomize.py there and call arbitrary code such as sys.path.insert(0, path), site.addsitedir(path).