getopt
— C-style parser for command line options¶
Código fuente: Lib/getopt.py
Obsoleto desde la versión 3.13: The getopt
module is soft deprecated and will not be
developed further; development will continue with the argparse
module.
Nota
The getopt
module is a parser for command line options whose API is
designed to be familiar to users of the C getopt()
function. Users who
are unfamiliar with the C getopt()
function or who would like to write
less code and get better help and error messages should consider using the
argparse
module instead.
This module helps scripts to parse the command line arguments in sys.argv
.
It supports the same conventions as the Unix 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.
Este módulo proporciona dos funciones y una excepción:
- getopt.getopt(args, shortopts, longopts=[])¶
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:]
. shortopts is the string of option letters that the script wants to recognize, with options that require an argument followed by a colon (':'
) and options that accept an optional argument followed by two colons ('::'
); i.e., the same format that Unixgetopt()
uses.Nota
Unlike GNU
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.longopts, 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 ('='
). Long options which accept an optional argument should be followed by an equal sign and question mark ('=?'
). To accept only long options, shortopts 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 longopts is['foo', 'frob']
, the option--fo
will match as--foo
, but--f
will not match uniquely, soGetoptError
will be raised.El valor de retorno consta de dos elementos: el primero es una lista de pares
(option, value)
; el segundo es la lista de argumentos del programa que quedan después de que se eliminó la lista de opciones (esta es una porción final de args). Cada par de opción y valor retornado tiene la opción como su primer elemento, con un guión para las opciones cortas (por ejemplo,'-x'
) o dos guiones para las opciones largas (por ejemplo,'--long-option'
), y el argumento de la opción como su segundo elemento, o una cadena vacía si la opción no tiene argumento. Las opciones aparecen en la lista en el mismo orden en que se encontraron, lo que permite múltiples ocurrencias. Las opciones largas y cortas pueden ser mixtas.Distinto en la versión 3.14: Optional arguments are supported.
- getopt.gnu_getopt(args, shortopts, longopts=[])¶
Esta función funciona como
getopt()
, excepto que el modo de escaneo estilo GNU se usa por defecto. Esto significa que los argumentos opcionales y no opcionales pueden estar mezclados. La funcióngetopt()
detiene el procesamiento de opciones tan pronto como se encuentra un argumento no-opcionales.If the first character of the option string is
'+'
, or if the environment variablePOSIXLY_CORRECT
is set, then option processing stops as soon as a non-option argument is encountered.If the first character of the option string is
'-'
, non-option arguments that are followed by options are added to the list of option-and-value pairs as a pair that hasNone
as its first element and the list of non-option arguments as its second element. The second element of thegnu_getopt()
result is a list of program arguments after the last option.Distinto en la versión 3.14: Support for returning intermixed options and non-option arguments in order.
- exception getopt.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
msg
andopt
give the error message and related option; if there is no specific option to which the exception relates,opt
is an empty string.
- exception getopt.error¶
Alias para
GetoptError
; para compatibilidad con versiones anteriores.
Un ejemplo que usa solo opciones de estilo Unix:
>>> 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']
Usar nombres largos de opciones es igualmente fácil:
>>> 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']
Optional arguments should be specified explicitly:
>>> s = '-Con -C --color=off --color a1 a2'
>>> args = s.split()
>>> args
['-Con', '-C', '--color=off', '--color', 'a1', 'a2']
>>> optlist, args = getopt.getopt(args, 'C::', ['color=?'])
>>> optlist
[('-C', 'on'), ('-C', ''), ('--color', 'off'), ('--color', '')]
>>> args
['a1', 'a2']
The order of options and non-option arguments can be preserved:
>>> s = 'a1 -x a2 a3 a4 --long a5 a6'
>>> args = s.split()
>>> args
['a1', '-x', 'a2', 'a3', 'a4', '--long', 'a5', 'a6']
>>> optlist, args = getopt.gnu_getopt(args, '-x:', ['long='])
>>> optlist
[(None, ['a1']), ('-x', 'a2'), (None, ['a3', 'a4']), ('--long', 'a5')]
>>> args
['a6']
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(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()
Note that an equivalent command line interface could be produced with less code
and more informative help and error messages by using the argparse
module:
import argparse
if __name__ == '__main__':
parser = argparse.ArgumentParser()
parser.add_argument('-o', '--output')
parser.add_argument('-v', dest='verbose', action='store_true')
args = parser.parse_args()
# ... do something with args.output ...
# ... do something with args.verbose ..
Ver también
- Módulo
argparse
Opción de línea de comando alternativa y biblioteca de análisis de argumentos.