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
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 module version of
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