def main()

in build/env_dump.py [0:0]


def main():
  parser = optparse.OptionParser()
  parser.add_option('-f', '--output-json',
                    help='File to dump the environment as JSON into.')
  parser.add_option(
      '-d', '--dump-mode', action='store_true',
      help='Dump the environment to sys.stdout and exit immediately.')

  parser.disable_interspersed_args()
  options, args = parser.parse_args()
  if options.dump_mode:
    if args or options.output_json:
      parser.error('Cannot specify args or --output-json with --dump-mode.')
    json.dump(dict(os.environ), sys.stdout)
  else:
    if not options.output_json:
      parser.error('Requires --output-json option.')

    envsetup_cmd = ' '.join(map(pipes.quote, args))
    full_cmd = [
        'bash', '-c',
        '. %s > /dev/null; %s -d' % (envsetup_cmd, os.path.abspath(__file__))
    ]
    try:
      output = subprocess.check_output(full_cmd, universal_newlines=True)
    except Exception as e:
      sys.exit('Error running %s and dumping environment.' % envsetup_cmd)

    env_diff = {}
    new_env = json.loads(output)
    for k, val in list(new_env.items()):
      if k == '_' or (k in os.environ and os.environ[k] == val):
        continue
      env_diff[k] = val
    with open(options.output_json, 'w') as f:
      json.dump(env_diff, f)