Python argparse

Command-line processing

As of Python 2.7, the preferred command-line parsing library is argparse. The pattern is straightforward – create an ArgumentParser, add all the command-line options, then call it and extract arguments.

import argparse
def commandline():
  parser = argparse.ArgumentParser(
    description='Your command-line description',

  parser.add_argument('path', nargs='*', help='help string')
  parser.add_argument('--user', action='append', help='help string')
  parser.add_argument('--verbose', action='count', default=0, help='help string')
  parser.add_argument('--quiet', action='store_true', help='help string')

  args = parser.parser_args()

  print '  path   =    %s' % ',\n              '.join(args.path)
  print '  user   =    %s' % ',\n              '.join(args.user)
  print '  verbose= %d' % args.verbose
  print '  quiet = %s' % 'True' if args.quiet else 'False'


sub/one sub/three --user=sub/two --verbose --quiet --verbose

this produces

path    = sub/one
user    = sub/two
verbose = 2
quiet   = True

Arguments are positional or optional. In the example above, all arguments not attached to one of the listed options is gathered up into the ‘path’ positional argument.

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