getopt python commandline arguments parameters usage verbose help dry-run - all in one example

getopt_python_example.py

#!/usr/bin/env python

# This file is intended to be a quick template for making a commandline tool in python using getopt to hande the arguments.

import sys, os, re, getopt

def usage():
   # output comparable to argparse
   # https://docs.python.org/2/library/argparse.html#module-argparse
   filename = os.path.basename(__file__)
   print """
   usage: {file} [OPTIONS]
   
   options:
      -h, --help, -?                Print this usage info
      -v, --verbose                 Verbose output
      -n, --dry-run                 Don't write changes

   """.format(file=filename)

def main(args_in):
   print args_in

   # https://docs.python.org/2/library/getopt.html
   try:
      opts, args = getopt.getopt(args_in,"h?vn",["help","verbose","dry-run"])
   except getopt.GetoptError as err:
      print str(err)
      usage()
      sys.exit(2)
   
   verbose = 0
   dry_run = False
   for o, a in opts:
      if o in ("-h","--help","-?"):
         usage()
         sys.exit()
      elif o in ("-v","--verbose"):
         verbose += 1
      elif o in ("-n","--dry-run"):
         dry_run = True
      else:
         assert False, "unhandled option: {0}".format(o)

   if verbose > 0:
      print "verbose is on!" 
   
   if not dry_run:
      # do execute here

if __name__ == "__main__":
   sys.exit(main(sys.argv[1:]))