Substitutes environment variables into the given path

envify.py

#!/usr/bin/python3
import os, sys
# This script takes a string as an argument and outputs the same path with as many
# environment variables substituted in as possible.
def variable_syntax(variable_name):
    try:
        return {
            "nt": lambda variable_name: "%" + variable_name + "%",
            "posix": lambda variable_name: "$" + variable_name
        }[os.name](variable_name)
    except KeyError:
        quit("This operating system is not supported.")
def envify(path):
    # Start with the environment variable with the longest value.
    for variable_name, value in envify.environ:
        # Replace instances of the value of the environment variable with
        # the name of the environment variable.
        path = path.replace(value, variable_syntax(variable_name))
    return path
def envify_refresh():
    # Get a list of environment variables sorted by value length in descending order.
    # Each element is a tuple like (variable name, value).
    envify.environ = sorted(os.environ.items(), key=lambda variable: len(variable[1]), reverse=True)
envify_refresh()
def main(argc, argv):
    if argc < 2:
        print("Pass a path in as an argument.")
    else:
        # Iterate through all arguments, skipping the first.
        arguments = iter(argv)
        next(arguments)
        for path in arguments:
            print(envify(path))
if __name__ == "__main__":
    main(len(sys.argv), sys.argv)