.. _environment-variables: ********************* Environment Variables ********************* .. contents:: :backlinks: none .. envvar:: HOME The user's home directory. On linux, :envvar:`~ ` is shorthand for :envvar:`HOME`. .. envvar:: PATH The list of directories searched to find executable programs .. envvar:: PYTHONPATH The list of directories that is added to Python's standard search list when importing packages and modules .. envvar:: MPLCONFIGDIR This is the directory used to store user customizations to matplotlib, as well as some caches to improve performance. If :envvar:`MPLCONFIGDIR` is not defined, :file:`{HOME}/.config/matplotlib` is generally used on unix-like systems and :file:`{HOME}/.matplotlib` is used on other platforms, if they are writable. Otherwise, the python standard library :func:`tempfile.gettempdir` is used to find a base directory in which the :file:`matplotlib` subdirectory is created. .. envvar:: MPLBACKEND This optional variable can be set to choose the matplotlib backend. See :ref:`what-is-a-backend`. .. _setting-linux-osx-environment-variables: Setting environment variables in Linux and OS-X =============================================== To list the current value of :envvar:`PYTHONPATH`, which may be empty, try:: echo $PYTHONPATH The procedure for setting environment variables in depends on what your default shell is. :program:`BASH` seems to be the most common, but :program:`CSH` is also common. You should be able to determine which by running at the command prompt:: echo $SHELL BASH/KSH -------- To create a new environment variable:: export PYTHONPATH=~/Python To prepend to an existing environment variable:: export PATH=~/bin:${PATH} The search order may be important to you, do you want :file:`~/bin` to be searched first or last? To append to an existing environment variable:: export PATH=${PATH}:~/bin To make your changes available in the future, add the commands to your :file:`~/.bashrc` file. CSH/TCSH -------- To create a new environment variable:: setenv PYTHONPATH ~/Python To prepend to an existing environment variable:: setenv PATH ~/bin:${PATH} The search order may be important to you, do you want :file:`~/bin` to be searched first or last? To append to an existing environment variable:: setenv PATH ${PATH}:~/bin To make your changes available in the future, add the commands to your :file:`~/.cshrc` file. .. _setting-windows-environment-variables: Setting environment variables in windows ======================================== Open the :program:`Control Panel` (:menuselection:`Start --> Control Panel`), start the :program:`System` program. Click the :guilabel:`Advanced` tab and select the :guilabel:`Environment Variables` button. You can edit or add to the :guilabel:`User Variables`.