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authorGeorg Brandl <georg@python.org>2007-08-15 14:28:22 (GMT)
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+
+:mod:`getopt` --- Parser for command line options
+=================================================
+
+.. module:: getopt
+ :synopsis: Portable parser for command line options; support both short and long option
+ names.
+
+
+This module helps scripts to parse the command line arguments in ``sys.argv``.
+It supports the same conventions as the Unix :cfunc:`getopt` function (including
+the special meanings of arguments of the form '``-``' and '``-``\ ``-``'). Long
+options similar to those supported by GNU software may be used as well via an
+optional third argument. This module provides a single function and an
+exception:
+
+.. % That's to fool latex2html into leaving the two hyphens alone!
+
+
+.. function:: getopt(args, options[, long_options])
+
+ Parses command line options and parameter list. *args* is the argument list to
+ be parsed, without the leading reference to the running program. Typically, this
+ means ``sys.argv[1:]``. *options* is the string of option letters that the
+ script wants to recognize, with options that require an argument followed by a
+ colon (``':'``; i.e., the same format that Unix :cfunc:`getopt` uses).
+
+ .. note::
+
+ Unlike GNU :cfunc:`getopt`, after a non-option argument, all further arguments
+ are considered also non-options. This is similar to the way non-GNU Unix systems
+ work.
+
+ *long_options*, if specified, must be a list of strings with the names of the
+ long options which should be supported. The leading ``'-``\ ``-'`` characters
+ should not be included in the option name. Long options which require an
+ argument should be followed by an equal sign (``'='``). To accept only long
+ options, *options* should be an empty string. Long options on the command line
+ can be recognized so long as they provide a prefix of the option name that
+ matches exactly one of the accepted options. For example, if *long_options* is
+ ``['foo', 'frob']``, the option :option:`--fo` will match as :option:`--foo`,
+ but :option:`--f` will not match uniquely, so :exc:`GetoptError` will be raised.
+
+ The return value consists of two elements: the first is a list of ``(option,
+ value)`` pairs; the second is the list of program arguments left after the
+ option list was stripped (this is a trailing slice of *args*). Each
+ option-and-value pair returned has the option as its first element, prefixed
+ with a hyphen for short options (e.g., ``'-x'``) or two hyphens for long
+ options (e.g., ``'-``\ ``-long-option'``), and the option argument as its
+ second element, or an empty string if the option has no argument. The
+ options occur in the list in the same order in which they were found, thus
+ allowing multiple occurrences. Long and short options may be mixed.
+
+
+.. function:: gnu_getopt(args, options[, long_options])
+
+ This function works like :func:`getopt`, except that GNU style scanning mode is
+ used by default. This means that option and non-option arguments may be
+ intermixed. The :func:`getopt` function stops processing options as soon as a
+ non-option argument is encountered.
+
+ If the first character of the option string is '+', or if the environment
+ variable POSIXLY_CORRECT is set, then option processing stops as soon as a
+ non-option argument is encountered.
+
+ .. versionadded:: 2.3
+
+
+.. exception:: GetoptError
+
+ This is raised when an unrecognized option is found in the argument list or when
+ an option requiring an argument is given none. The argument to the exception is
+ a string indicating the cause of the error. For long options, an argument given
+ to an option which does not require one will also cause this exception to be
+ raised. The attributes :attr:`msg` and :attr:`opt` give the error message and
+ related option; if there is no specific option to which the exception relates,
+ :attr:`opt` is an empty string.
+
+ .. versionchanged:: 1.6
+ Introduced :exc:`GetoptError` as a synonym for :exc:`error`.
+
+
+.. exception:: error
+
+ Alias for :exc:`GetoptError`; for backward compatibility.
+
+An example using only Unix style options::
+
+ >>> import getopt
+ >>> args = '-a -b -cfoo -d bar a1 a2'.split()
+ >>> args
+ ['-a', '-b', '-cfoo', '-d', 'bar', 'a1', 'a2']
+ >>> optlist, args = getopt.getopt(args, 'abc:d:')
+ >>> optlist
+ [('-a', ''), ('-b', ''), ('-c', 'foo'), ('-d', 'bar')]
+ >>> args
+ ['a1', 'a2']
+
+Using long option names is equally easy::
+
+ >>> s = '--condition=foo --testing --output-file abc.def -x a1 a2'
+ >>> args = s.split()
+ >>> args
+ ['--condition=foo', '--testing', '--output-file', 'abc.def', '-x', 'a1', 'a2']
+ >>> optlist, args = getopt.getopt(args, 'x', [
+ ... 'condition=', 'output-file=', 'testing'])
+ >>> optlist
+ [('--condition', 'foo'), ('--testing', ''), ('--output-file', 'abc.def'), ('-x',
+ '')]
+ >>> args
+ ['a1', 'a2']
+
+In a script, typical usage is something like this::
+
+ import getopt, sys
+
+ def main():
+ try:
+ opts, args = getopt.getopt(sys.argv[1:], "ho:v", ["help", "output="])
+ except getopt.GetoptError as err:
+ # print help information and exit:
+ print str(err) # will print something like "option -a not recognized"
+ usage()
+ sys.exit(2)
+ output = None
+ verbose = False
+ for o, a in opts:
+ if o == "-v":
+ verbose = True
+ elif o in ("-h", "--help"):
+ usage()
+ sys.exit()
+ elif o in ("-o", "--output"):
+ output = a
+ else:
+ assert False, "unhandled option"
+ # ...
+
+ if __name__ == "__main__":
+ main()
+
+
+.. seealso::
+
+ Module :mod:`optparse`
+ More object-oriented command line option parsing.
+