On Mac 10.11.6, using GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin15) the set +a command appears to not work:script.py#!/usr/bin/pythonimport osprint(VAR0 is:, os.environ.get(VAR0)Commands:$ VAR0=abc$ ./script.py('VAR0 is:', None)   # expected$ set -a$ VAR0=abc$ ./script.py('VAR0 is:', 'abc')   # expected, VAR0 has been exported to the environment and script.py has access to it$ set +a$ VAR0=def$ ./script.py('VAR0 is:', 'def')   # <= unexpected
set +a does not unset the -a flag
bash;environment variables