Doc/libgetopt.tex

   1 \section{Standard Module \sectcode{getopt}}
   2
   3 \stmodindex{getopt}
   4 This module helps scripts to parse the command line arguments in
   5 \code{sys.argv}.
   6 It uses the same conventions as the \UNIX{}
   7 \code{getopt()}
   8 function (including the special meanings of arguments of the form
   9 \samp{-} and \samp{--}).
  10 It defines the function
  11 \code{getopt.getopt(args, options)}
  12 and the exception
  13 \code{getopt.error}.
  14
  15 The first argument to
  16 \code{getopt()}
  17 is the argument list passed to the script with its first element
  18 chopped off (i.e.,
  19 \code{sys.argv[1:]}).
  20 The second argument is the string of option letters that the
  21 script wants to recognize, with options that require an argument
  22 followed by a colon (i.e., the same format that \UNIX{}
  23 \code{getopt()}
  24 uses).
  25 The return value consists of two elements: the first is a list of
  26 option-and-value pairs; the second is the list of program arguments
  27 left after the option list was stripped (this is a trailing slice of the
  28 first argument).
  29 Each option-and-value pair returned has the option as its first element,
  30 prefixed with a hyphen (e.g.,
  31 \code{'-x'}),
  32 and the option argument as its second element, or an empty string if the
  33 option has no argument.
  34 The options occur in the list in the same order in which they were
  35 found, thus allowing multiple occurrences.
  36 Example:
  37
  38 \bcode\begin{verbatim}
  39 >>> import getopt, string
  40 >>> args = string.split('-a -b -cfoo -d bar a1 a2')
  41 >>> args
  42 ['-a', '-b', '-cfoo', '-d', 'bar', 'a1', 'a2']
  43 >>> optlist, args = getopt.getopt(args, 'abc:d:')
  44 >>> optlist
  45 [('-a', ''), ('-b', ''), ('-c', 'foo'), ('-d', 'bar')]
  46 >>> args
  47 ['a1', 'a2']
  48 >>>
  49 \end{verbatim}\ecode
  50
  51 The exception
  52 \code{getopt.error = 'getopt error'}
  53 is raised when an unrecognized option is found in the argument list or
  54 when an option requiring an argument is given none.
  55 The argument to the exception is a string indicating the cause of the
  56 error.