gistfile1.py

opt_regex = re.compile(r'''
    (?P<opt>--?(?:\?|\#|(?:\w+-)*\w+))  # option starts with - or -- and can have - in the middle but not at the end, also allow '-?'
    (?:
     (?:\s*(=)?\s*)           # -a=
     (?P<argoptional>[<\[])?  # -a=< or -a=[
     (?:\s*(=)?\s*)           # or maybe -a<=
     (?P<arg>
      (?(argoptional)         # if we think we have an arg (we saw [ or <)
       [^\]>]+                # either read everything until the closing ] or >
       |
       (?(2)
        [-a-zA-Z]+             # or if we didn't see [ or < but just saw =, read all letters, e.g. -a=abc
        |
        [A-Z]+                # but if we didn't have =, only allow uppercase letters, e.g. -a FOO
       )
      )
     )
     (?(argoptional)(?P<argoptionalc>[\]>])) # read closing ] or > if we have an arg
    )?                        # the whole arg thing is optional
    (?P<ending>,\s*|\s+|\Z|/|\|)''', re.X) # read any trailing whitespace or the end of the string

opt2_regex = re.compile(r'''
        (?P<opt>\w+)    # an option that doesn't start with any of the usual characters, e.g. options from 'dd' like bs=BYTES
        (?:
         (?:\s*=\s*)    # an optional arg, e.g. bs=BYTES
         (?P<arg>\w+)
        )
        (?:,\s*|\s+|\Z)''', re.X) # end with , or whitespace or the end of the string