Python using diferent options multiple times with argparse

问题

I am working on a custom Nagios script in which I would like to implement parsing of command line arguments in the same way that is used on existing Nagios Plugin check_disk.

In that plugin you have an option parameter -C to Clear current config and start over with new parameters.

Extracted from check_disk help:

check_disk -w 100 -c 50 -C -w 1000 -c 500 -p /foo -C -w 5% -c 3% -p /bar
           ----(3)-----    ---------(1)----------    --------(2)--------

Checks warning/critical thresholds:

for volume /foo use 1000M and 500M as thresholds
for volume /bar use 5% and 3%
All remaining volumes use 100M and 50M

I have tried with argparse and some parameter as action='append' but repeated arguments are stored in a list and missing ones are not includes as a "None" entry.

I have also tried with parse_known_args hoping to stop parsing on first unknown argument, but I get a namespace with all known arguments and a list of unknown arguments.

I guess that my only option is using regular expressions before parsing the command line arguments.

import re
import argparse
import sys

parser = argparse.ArgumentParser()
parser.add_argument('-w', help='warning')
parser.add_argument('-c', help='critical')
parser.add_argument('-p', help='path')

separator=r'-S'
groups = re.split(separator, '|'.join(sys.argv[1:])))

args = []
for idx, group_args in enumerate(groups):
   args.append('')
   args[idx]=parser.parse_args(group_args.split('|'))

I do not know if argparse can handle this kind of scenario without need to split using regular expressions.

Or if this is the best approach I can find.

This is not related with Using the same option multiple times in Python's argparse because it is not the same case, I have different optional argument not just one option with multiple values.

In example above (3) have not got option -p, (1) and (2) have it. That is one of the difference and one of the problems. If all options were mandatory, it was easy.

回答1:

To handle this:

check_disk -w 100 -c 50 -C -w 1000 -c 500 -p /foo -C -w 5% -c 3% -p /bar

I can imagine starting with a namespace

args = argparse.Namespace(w:[None], c:[None], p:[None])
args = parser.parse_args(args=args)

and define a couple of custom Action classes.

For `-C` use a class that appends a `None` to each of those 3 attributes
    namespace['w'].append(None), etc

For each of `w`, `c` and `p`, an Action class, that replaces the last `None`
    with the users value.

In other words, use the C argument to 'reset' by advancing the lists, and then use the others to to adjust the default default values.

Alternatively start with a Namespace(C=[[None, None, None]]), and add append a list with each 'C'. Then 'w' would set the namespace['C'][-1][0] etc. (Or use a list of dicts).

来源：https://stackoverflow.com/questions/62524681/python-using-diferent-options-multiple-times-with-argparse

标签

python

regex

argparse