Module posix defines the following data item:
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.