Setting options from environment variables when using argparse

Question

I have a script which has certain options that can either be passed on the command line, or from environment variables. The CLI should take precedence if both are present, a

Answer 1

You can use OptionParser()

from optparse import OptionParser

def argument_parser(self, parser):
    parser.add_option('--foo', dest="foo", help="foo", default=os.environ.get('foo', None))
    parser.add_option('--bar', dest="bar", help="bar", default=os.environ.get('bar', None))
    return(parser.parse_args())

parser = OptionParser()
(options, args) = argument_parser(parser)
foo = options.foo
bar = options.bar
print("foo: {}".format(foo))
print("bar: {}".format(bar))

shell:

export foo=1
export bar=2
python3 script.py