Python getopt参数过多

Question

I am at a dead end. I am trying to pass arguments into a Linux to run certain operations. I want to avoid the user from entering too many paramters.

For example the desired running of the script would be as such:

./audit.py -a

I want to prevent the following:

./audit.py -af

This seems to be running whatever is specified for 'a' and then 'f'. In this case if it is like '-af' then I need it to quit with a sys.exit(). My len(sys.argv[1:]) always produces a result of 1 no matter how parameters I put in.

import getopts
import sys
def main():
    try:
        opts, args = getopt.getopt(sys.argv[1:], 'v:adfh')
    except getopt.GetoptError as err:
        sys.exit(str(err))
    if len(sys.argv[1:]) != 1:
        sys.exit('Invalid')

    for o,a in opts:
        if o in ('-v', '--volume'):
            print 'Volumes'
        elif len(sys.argv[2:]) != 0:
            sys.exit('Too many arguments')
        elif o in ('-a', '--agent'):
            print 'Full audit of agents only'
        elif o in ('-d', '--device'):
            print 'Full audit of device only'
        elif o in ('-f', '--full'):
            print 'Full audit of device/agents'
        elif o in ('-h', '--help'):
            sys.exit('Help Section')
if __name__ == '__main__':
    main()

Answer 1

The value of sys.argv[1:] is ['-af'] and if you will check for lenght of ['-af'] is 1 which is why if len(sys.argv[1:]) != 1: is always false. Instead if you want to check the length of first argument either you need to use len(sys.argv[1:][0]) or else for each of the arguments lengths.

Answer 2

The problem is that sys.argv[1:] produces a slice . In other words, it's a list. In your case, it's something like ['-af'] . So of course, the length will always be 1 except if you passed no parameters. Perhaps you meant to do this:

if not all(i < 1 for i in sys.argv[1:]):
    sys.exit('Invalid')

Answer 3

You are looking at option clustering. There does not seem to be any facility in getopt to disable this feature. However, you probably shouldn't be using this package, anyway. Would argparse perhaps be more suitable for your needs?

Answer 4

Not a full answer but you might be glad to look at a library I was very happy to find.

docopts - there is a great video describing how to use

This is a great tool, you just describe your arguments in the module document section, eg;

'''
Usage:
   myprog -a -v <volumes>...
   myprog -f
   myprog -h | --help
'''
import docopt
args=docopt.docopt(__doc__)

This will produce the following dictionary if run as myprog -a -v one two three ;

{
  "--help": false, 
  "-a": true, 
  "-f": false, 
  "-h": false, 
  "-v": true, 
  "": [
    "myprog", 
    "one", 
    "two", 
    "three"
  ]
}