8.1.2 Module Contents
Keywords: lib

##
8.1.2 Module Contents

Module `posix` defines the following data item:

`environ`
  A dictionary representing the string environment at the time the interpreter was started. For example, `environ['HOME']` is the pathname of your home directory, equivalent to `getenv("HOME")` in C.

  Modifying this dictionary does not affect the string environment passed on by `execv()`, `popen()` or `system()`; if you need to change the environment, pass `environ` to `execve()` or add variable assignments and export statements to the command string for `system()` or `popen()`.

  Note: The `os` module provides an alternate implementation of `environ` which updates the environment on modification. Note also that updating `os.environ` will render this dictionary obsolete. Use of the `os` for this is recommended over direct access to the `posix` module.

Additional contents of this module should only be accessed via the `os` module; refer to the documentation for that module for further information.