File entry lister script

File entry lister

In this example we create a file entry lister script that can be pointed at a directory or an image file.

Initial boiler plate

First let's start with the initial boiler plate:

• the shebang
• the encoding of the source file
• a description of what the script is supposed to do
• the main function skeleton

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""Script to list file entries."""

from __future__ import print_function
from __future__ import unicode_literals

# TODO: add imports here.
import sys


# TODO: add classes here.


def Main():
  """The main program function.

  Returns:
    bool: True if successful or False if not.
  """
  # TODO: add main program logic here.

  return True


if __name__ == '__main__':
  if not Main():
    sys.exit(1)
  else:
    sys.exit(0)

Argument handling

For the program argument handling we'll use argparse.

Add the necessary import:

import argparse

And to the Main function add code that sets:

• the program description
• a program argument named source

  argument_parser = argparse.ArgumentParser(description=(
      'Lists file entries in a directory or storage media image.'))

  argument_parser.add_argument(
      'source', nargs='?', action='store', metavar='image.raw',
      default=None, help=(
          'path of the directory or filename of a storage media image '
          'containing the file.'))

  options = argument_parser.parse_args()

  if not options.source:
    print('Source value is missing.')
    print('')
    argument_parser.print_help()
    print('')
    return False

Logging

For notifying errors, warnings or debug information we'll use logging.

Add the necessary import:

import logging

And to the Main function add code that sets:

• the logging configuration

  logging.basicConfig(
      level=logging.INFO, format='[%(levelname)s] %(message)s')

The file entry lister class

TODO: complete section