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The getopt module exists since the initial revision of the Python source code (1990). The optparse module was added to Python 2.3. When Python 2.7 added the 3rd argparse module, the optparse module was soft deprecated. Soft deprecate the getopt module.
170 lines
6.6 KiB
ReStructuredText
170 lines
6.6 KiB
ReStructuredText
:mod:`getopt` --- C-style parser for command line options
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=========================================================
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.. module:: getopt
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:synopsis: Portable parser for command line options; support both short and
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long option names.
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**Source code:** :source:`Lib/getopt.py`
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.. deprecated:: 3.13
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The :mod:`getopt` module is :term:`soft deprecated` and will not be
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developed further; development will continue with the :mod:`argparse`
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module.
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.. note::
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The :mod:`getopt` module is a parser for command line options whose API is
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designed to be familiar to users of the C :c:func:`!getopt` function. Users who
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are unfamiliar with the C :c:func:`!getopt` function or who would like to write
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less code and get better help and error messages should consider using the
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:mod:`argparse` module instead.
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--------------
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This module helps scripts to parse the command line arguments in ``sys.argv``.
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It supports the same conventions as the Unix :c:func:`!getopt` function (including
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the special meanings of arguments of the form '``-``' and '``--``'). Long
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options similar to those supported by GNU software may be used as well via an
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optional third argument.
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This module provides two functions and an
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exception:
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.. function:: getopt(args, shortopts, longopts=[])
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Parses command line options and parameter list. *args* is the argument list to
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be parsed, without the leading reference to the running program. Typically, this
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means ``sys.argv[1:]``. *shortopts* is the string of option letters that the
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script wants to recognize, with options that require an argument followed by a
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colon (``':'``; i.e., the same format that Unix :c:func:`!getopt` uses).
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.. note::
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Unlike GNU :c:func:`!getopt`, after a non-option argument, all further
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arguments are considered also non-options. This is similar to the way
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non-GNU Unix systems work.
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*longopts*, if specified, must be a list of strings with the names of the
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long options which should be supported. The leading ``'--'`` characters
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should not be included in the option name. Long options which require an
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argument should be followed by an equal sign (``'='``). Optional arguments
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are not supported. To accept only long options, *shortopts* should be an
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empty string. Long options on the command line can be recognized so long as
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they provide a prefix of the option name that matches exactly one of the
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accepted options. For example, if *longopts* is ``['foo', 'frob']``, the
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option ``--fo`` will match as ``--foo``, but ``--f`` will
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not match uniquely, so :exc:`GetoptError` will be raised.
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The return value consists of two elements: the first is a list of ``(option,
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value)`` pairs; the second is the list of program arguments left after the
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option list was stripped (this is a trailing slice of *args*). Each
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option-and-value pair returned has the option as its first element, prefixed
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with a hyphen for short options (e.g., ``'-x'``) or two hyphens for long
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options (e.g., ``'--long-option'``), and the option argument as its
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second element, or an empty string if the option has no argument. The
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options occur in the list in the same order in which they were found, thus
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allowing multiple occurrences. Long and short options may be mixed.
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.. function:: gnu_getopt(args, shortopts, longopts=[])
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This function works like :func:`getopt`, except that GNU style scanning mode is
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used by default. This means that option and non-option arguments may be
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intermixed. The :func:`getopt` function stops processing options as soon as a
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non-option argument is encountered.
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If the first character of the option string is ``'+'``, or if the environment
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variable :envvar:`!POSIXLY_CORRECT` is set, then option processing stops as
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soon as a non-option argument is encountered.
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.. exception:: GetoptError
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This is raised when an unrecognized option is found in the argument list or when
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an option requiring an argument is given none. The argument to the exception is
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a string indicating the cause of the error. For long options, an argument given
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to an option which does not require one will also cause this exception to be
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raised. The attributes :attr:`!msg` and :attr:`!opt` give the error message and
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related option; if there is no specific option to which the exception relates,
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:attr:`!opt` is an empty string.
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.. XXX deprecated?
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.. exception:: error
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Alias for :exc:`GetoptError`; for backward compatibility.
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An example using only Unix style options:
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>>> import getopt
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>>> args = '-a -b -cfoo -d bar a1 a2'.split()
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>>> args
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['-a', '-b', '-cfoo', '-d', 'bar', 'a1', 'a2']
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>>> optlist, args = getopt.getopt(args, 'abc:d:')
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>>> optlist
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[('-a', ''), ('-b', ''), ('-c', 'foo'), ('-d', 'bar')]
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>>> args
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['a1', 'a2']
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Using long option names is equally easy:
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>>> s = '--condition=foo --testing --output-file abc.def -x a1 a2'
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>>> args = s.split()
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>>> args
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['--condition=foo', '--testing', '--output-file', 'abc.def', '-x', 'a1', 'a2']
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>>> optlist, args = getopt.getopt(args, 'x', [
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... 'condition=', 'output-file=', 'testing'])
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>>> optlist
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[('--condition', 'foo'), ('--testing', ''), ('--output-file', 'abc.def'), ('-x', '')]
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>>> args
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['a1', 'a2']
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In a script, typical usage is something like this::
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import getopt, sys
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def main():
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try:
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opts, args = getopt.getopt(sys.argv[1:], "ho:v", ["help", "output="])
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except getopt.GetoptError as err:
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# print help information and exit:
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print(err) # will print something like "option -a not recognized"
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usage()
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sys.exit(2)
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output = None
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verbose = False
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for o, a in opts:
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if o == "-v":
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verbose = True
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elif o in ("-h", "--help"):
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usage()
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sys.exit()
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elif o in ("-o", "--output"):
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output = a
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else:
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assert False, "unhandled option"
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# ...
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if __name__ == "__main__":
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main()
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Note that an equivalent command line interface could be produced with less code
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and more informative help and error messages by using the :mod:`argparse` module::
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import argparse
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if __name__ == '__main__':
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parser = argparse.ArgumentParser()
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parser.add_argument('-o', '--output')
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parser.add_argument('-v', dest='verbose', action='store_true')
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args = parser.parse_args()
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# ... do something with args.output ...
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# ... do something with args.verbose ..
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.. seealso::
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Module :mod:`argparse`
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Alternative command line option and argument parsing library.
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