In Python script, how do I set PYTHONPATH?
You can get and set environment variables via os.environ
:
import os
user_home = os.environ["HOME"]
os.environ["PYTHONPATH"] = "..."
But since your interpreter is already running, this will have no effect. You're better off using
import sys
sys.path.append("...")
which is the array that your PYTHONPATH
will be transformed into on interpreter startup.
If you put sys.path.append('dir/to/path')
without check it is already added, you could generate a long list in sys.path
. For that, I recommend this:
import sys
import os # if you want this directory
try:
sys.path.index('/dir/path') # Or os.getcwd() for this directory
except ValueError:
sys.path.append('/dir/path') # Or os.getcwd() for this directory
You don't set PYTHONPATH
, you add entries to sys.path
. It's a list of directories that should be searched for Python packages, so you can just append your directories to that list.
sys.path.append('/path/to/whatever')
In fact, sys.path
is initialized by splitting the value of PYTHONPATH
on the path separator character (:
on Linux-like systems, ;
on Windows).
You can also add directories using site.addsitedir
, and that method will also take into account .pth
files existing within the directories you pass. (That would not be the case with directories you specify in PYTHONPATH
.)
PYTHONPATH ends up in sys.path, which you can modify at runtime.
import sys
sys.path += ["whatever"]