How to use getopt/OPTARG in Python? How to shift arguments if too many arguments (9) are given?

Question

How to use getopt/optarg in Python?

Answer 1

A google search would have helped. Have a look at the getopt and argparse modules in the standard library:

import argparse  parser = argparse.ArgumentParser(description='Process some integers.') parser.add_argument('integers', metavar='N', type=int, nargs='+',                    help='an integer for the accumulator') parser.add_argument('--sum', dest='accumulate', action='store_const',                    const=sum, default=max,                    help='sum the integers (default: find the max)')  args = parser.parse_args() print args.accumulate(args.integers) 

Then run it as expected:

$ prog.py -h usage: prog.py [-h] [--sum] N [N ...]  Process some integers.  positional arguments:  N           an integer for the accumulator  optional arguments:  -h, --help  show this help message and exit  --sum       sum the integers (default: find the max) 

When run with the appropriate arguments, it prints either the sum or the max of the command-line integers:

$ prog.py 1 2 3 4 4  $ prog.py 1 2 3 4 --sum 10 

This is straight from the standard library.

Answer 2

This is an example of how I do it, I usually use the same basic template:

import sys import getopt  try:     opts, args = getopt.getopt(sys.argv[1:], 'm:p:h', ['miner=', 'params=', 'help']) except getopt.GetoptError:     usage()     sys.exit(2)  for opt, arg in opts:     if opt in ('-h', '--help'):         usage()         sys.exit(2)     elif opt in ('-m', '--miner'):         miner_name = arg     elif opt in ('-p', '--params'):         params = arg     else:         usage()         sys.exit(2) 

I don't think there is any 9 parameter limit.

Answer 3

Have you tried reading the python docs for the module getopt (http://docs.python.org/library/getopt.html?highlight=getopt#module-getopt)? It provides a simple example of how the getopt is used. What do you mean by shift arguments? If you want to check that the user does not use more than 9 arguments, you can check the length of the sys.argv list, which contains all the options/arguments passed to the script. The first element is the name of the script which is invoked, so the length is always at least 1. You could do something like:

if len(sys.argv) > 10
    print('Too many arguments.')