import sys

arguments with sys.argv

$ python3 report.py portfolio.csv prices.csv

sys.argv # ['report.py, 'portfolio.csv', 'prices.csv']

if len(sys.argv) != 3:
    raise SystemExit(f'Usage: {sys.argv[0]} ' 'portfile pricefile')
portfile = sys.argv[1]
pricefile = sys.argv[2]

sys.path

sys.exit(exitcode), raise SystemExit, raise SystemExit, raise SystemExit('Informative message')

Made with Super

sys.modules.keys() # ['copy_reg', '__main__', 'site', '__builtin__', 'encodings', 'encodings.encodings', 'posixpath', ...]
sys.path # ['', '/usr/local/lib/python36/python36.zip', '/usr/local/lib/python36',...]

sys.path.append('/project/foo/pyfiles')
$ env PYTHONPATH=/project/foo/pyfiles python3 OR export PYTHONPATH=$PYTHONPATH:$PWD

$ setenv NAME dave
name = os.environ['NAME']