问题
I'm currently working on a script that will be able to take multiple flags. I want it so that no matter what the last argument should be 'start|stop|status'.
#!/usr/bin/env python
from argparse import ArgumentParser
def argument_analysis():
"""
This will analyze arguments, and return the region as a string, the filter as a dictionary, and the command as a string.
:return: region,filters,command
"""
parser_options = ArgumentParser()
parser_options.add_argument("-r", "--region", dest='region',
help="Filter by region.")
parser_options.add_argument("-n", "--name", dest='name',
help="Filter by hostname.")
parser_options.add_argument("-P", "--project", dest='project',
help="Filter by Project tag.")
parser_options.add_argument("-U", "--usage", dest='usage',
help="Filter by Usage tag.")
parser_options.add_argument("-i", "--instance_id", dest='instance_id',
help="Filter by instance_id.")
parser_options.add_argument("-t", "--type", dest='type',
help="Filter by instance_size.")
parser_options.add_argument("-p", "--ip", dest='internal_ip',
help="Filter by internal_ip")
parser_options.add_argument("-c", "--command", dest='command',
help="stop/start, or check the status of instances.")
parser_options.add_argument("-a", "--all", dest='all', default=False, action='store_true',
help="No filter, display status of all servers.")
arguments = vars(parser_options.parse_args())
return arguments
if __name__ == '__main__':
print argument_analysis()
I want it so that ./argument_analysis_script.py will require a 'stop|start|status' at the end. I haven't had much luck getting help with the ARgumentParser(). If anybody has any suggestions it would be very helpful.
Thanks in advance for your time.
NOTE: I would like for the script to stop if [stop|start|restart|status] is not entered, and explain that [stop|start|restart|status] is required.
**UPDATE** **UPDATE** **UPDATE**
After doing some more digging, to be able to analyze/use command line options, and arguments, I stumbled upon OptionParser, which I avoided as docs.python.org states it's deprecated. Anyway, since that is the only thing that I could find to give me exactly what I wanted, here is an update of what I've got:
#!/usr/bin/env python
from optparse import OptionParser
def argument_analysis():
"""
This will analyze arguments, and return the region as a string, the filter as a dictionary, and the command as a string.
:return: region,filters,command
"""
parser = OptionParser()
parser.add_option("-r", "--region", dest='region',
help="Filter by region.")
parser.add_option("-n", "--name", dest='name',
help="Filter by hostname.")
parser.add_option("-P", "--project", dest='project',
help="Filter by Project tag.")
parser.add_option("-U", "--usage", dest='usage',
help="Filter by Usage tag.")
parser.add_option("-i", "--instance_id", dest='instance_id',
help="Filter by instance_id.")
parser.add_option("-t", "--type", dest='type',
help="Filter by instance_size.")
parser.add_option("-p", "--ip", dest='internal_ip',
help="Filter by internal_ip")
parser.add_option("-c", "--command", dest='command',
help="stop/start, or check the status of instances.")
parser.add_option("-a", "--all", dest='all', default=False, action='store_true',
help="No filter, display status of all servers.")
(options, args) = parser.parse_args() # Grab Options specifed from above, as well as actual Arguments.
options = vars(options) # Convert 'options' into dictionary: key=dest_name, value=dest_value
# Getting variables for dictionary below.
region_filter = options['region']
name_filter = options['name']
project_filter = options['project']
usage_filter = options['usage']
instance_filter = options['instance_id']
type_filter = options['type']
ip_filter = options['internal_ip']
all_filter = options['all']
region = region_filter if region_filter else 'us-east-1' # Return 'us-east-1' region is not specified.
filters = {'tag:Name': name_filter, 'tag:Project': project_filter, 'tag:Usage': usage_filter,
'instance-id': instance_filter, 'instance_type': type_filter, 'private-ip-address': ip_filter,
'all': all_filter}
command = 'No commands.' if not args else args #Return "No commands" if no command is specified.
return region, filters, command
if __name__ == '__main__':
opts_and_args = argument_analysis()
print "Region: " + str(opts_and_args[0])
print "Filters: " + str(opts_and_args[1])
print "Command: " + str(opts_and_args[2])
As you can see, you can apply whatever logic you want to based on the returned object, or within the definition. Thanks everybody for your assistance on this one.
回答1:
Maybe you can do this with argparse, but another option is to use the sys module
import sys
print sys.argv # prints command line arguments
sys.argv has the command line arguments in a list, so you can check the last one for whatever:
if sys.argv[-1] != 'start':
print "Error, expected <something>"
// quit
回答2:
Partially the same as Ben's answer, but extended with regex to avoid declaring an if statement for each case, e.g. start, stop.
import sys
import re
a = sys.argv[-1]
if not re.search(r"^(start|stop|restart|status)$", a):
raise Exception("start, stop, restart or status should be passed to this script instead of: \""+a+"\"")
回答3:
I recommend taking a look at docopt. It's not in the standard library, but it's definitely more powerful and intuitive. For example, in your case you could just do this:
docstring='''My Program.
Usage: my_prog [options] (flag1|flag2|flag3) (start|stop|restart|status)
Options:
-a stuff about this
-b more stuff
-c yet more stuff
-d finally stuff'''
from docopt import docopt
parsed = docopt(docstring)
来源：https://stackoverflow.com/questions/24833054/argument-parsing-in-python-required-vs-optional