How to read/process command line arguments?

 

I am originally a C programmer. I have seen numerous tricks and "hacks" to read many different arguments.

What are some of the ways Python programmers can do this?

Related

  • What's the best way to grab/parse command line arguments passed to a Python script?
  • Implementing a “[command] [action] [parameter]” style command-line interfaces?
  • How can I process command line arguments in Python?
  • How do I format positional argument help using Python's optparse?

    • Please note that optparse was deprecated in version 2.7 of Python:

    http://docs.python.org/2/library/optparse.html. argparse is the replacement: http://docs.python.org/2/library/argparse.html#module-argparse

    There are the following modules in the standard library:

  • The getopt module is similar to GNU getopt.
  • The optparse module offers object-oriented command line option parsing.

    • Here is an example that uses the latter from the docs: 

    from optparse import OptionParser

parser = OptionParser()
parser.add_option("-f", "--file", dest="filename",
                  help="write report to FILE", metavar="FILE")
parser.add_option("-q", "--quiet",
                  action="store_false", dest="verbose", default=True,
                  help="don't print status messages to stdout")

(options, args) = parser.parse_args()

    optparse supports (among other things):

  • Multiple options in any order.
  • Short and long options.
  • Default values.
  • Generation of a usage help message. 
    • import sys

print("n".join(sys.argv))

    sys.argv is a list that contains all the arguments passed to the script on the command line.

    Basically, 

    import sys
print(sys.argv[1:])

    Just going around evangelizing for argparse which is better for these reasons.. essentially:

    (copied from the link)

  • argparse module can handle positional and optional arguments, while optparse can handle only optional arguments

  • argparse isn't dogmatic about what your command line interface should look like - options like -file or /file are supported, as are required options. Optparse refuses to support these features, preferring purity over practicality

  • argparse produces more informative usage messages, including command-line usage determined from your arguments, and help messages for both positional and optional arguments. The optparse module requires you to write your own usage string, and has no way to display help for positional arguments.

  • argparse supports action that consume a variable number of command-line args, while optparse requires that the exact number of arguments (eg 1, 2, or 3) be known in advance

  • argparse supports parsers that dispatch to sub-commands, while optparse requires setting allow_interspersed_args and doing the parser dispatch manually

    • And my personal favorite:

  • argparse allows the type and action parameters to add_argument() to be specified with simple callables, while optparse requires hacking class attributes like STORE_ACTIONS or CHECK_METHODS to get proper argument checking
    • 链接地址: http://www.djcxy.com/p/30304.html

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