Last updated on September 23, 2020 by Dan Nanni
sys.pathused by the Python interpreter. How can I change the default
When the Python interpreter executes a program which imports a module, it examines all directory paths listed in
sys.path until it finds the module. By default,
sys.path is constructed as a concatenation of (1) the current working directory, (2) content of
PYTHONPATH environment variable, and (3) a set of default paths supplied by the installed Python interpreter.
If the module you are trying to import is not found in any of the directories defined in
sys.path, you will encounter the following error:
Import Error: No module named XXXXX
The error can occur either because the module is indeed missing on your system, or because the
sys.path does not point to the directory where the module is installed. In the latter case, you need to let the Python interpreter know where the module is found. Here is how to change
sys.path of your Python interpreter.
The first method is explicitly change
sys.path in your Python program.
You can check the content of the current
sys.path as follows.
import sys print(sys.path)
Once you find that
sys.path does not contain the necessary module directory (e.g.,
/custom/path/to/modules), you can incorporate the directory by adding the following lines before the
import sys sys.path.append('/custom/path/to/modules') . . . import <your-python-module>
Alternatively, you can add the custom module directory in
PYTHONPATH environment variable, which will augment the default module search paths used by the Python interpreter.
Add the following line to
~/.bashrc, which will have the effect of changing
sys.path in Python permanently.
The specified path will be added to
sys.path after the current working directory, but before the default interpreter-supplied paths.
If you want to change
PYTHONPATH variable temporarily, you can use the following command instead.
$ PYTHONPATH=$PYTHONPATH:/custom/path/to/modules python <your-program>
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