Python is recommended for getting command line arguments

This section looks at the sys, getopt module in python that handles command-line arguments

If you want to pass arguments to an python script, what is the corresponding argc in python, argv?

Module required: sys

Number of parameters: len(ES17en.argv)

Script name: ES21en. argv[0]
Parameter 1: ES24en. argv[1]
Parameter 2: ES27en. argv[2]

test.py

import sys
print " Script name: ", sys.argv[0]
for i in range(1, len(sys.argv)):
 print " parameter ", i, sys.argv[i]
>>>python test.py hello world

Script name: ES36en.py

Parameter 1 hello
Parameter 2 world

Use the command line option in python:

For example, we need an ES48en.py script. It processes one file and outputs the result to another.

The script is required to meet the following conditions:

1. Use the -ES54en-ES55en option to distinguish between input and output files.

>>> python convert.py -i inputfile -o outputfile

2. Print out the help information with -h when you do not know which parameters are required for convert.py

>>> python convert.py -h

getopt function:

getopt.getopt(args, options[, long_options])
convert.py
python test.py -i inputfile -o outputfile

import sys, getopt
opts, args = getopt.getopt(sys.argv[1:], "hi:o:")
input_file=""
output_file=""
for op, value in opts:
 if op == "-i":
  input_file = value
 elif op == "-o":
  output_file = value
 elif op == "-h":
  usage()
  sys.exit()

Code explanation:

a) sys. argv[1:] for the parameter list to be processed, sys. argv[0] is the script name, so use sys. argv[1:] to filter out the script name.

(b) "hi: ": Writes the option character in the analysis string when an option merely indicates the on-off state, i.e., when no additional parameter is followed. When the selected item is followed by an additional parameter, write the option character in the analysis string followed by a ":" sign.

So "hi:o:" means "h" is an on-off option;

"i:" and "o:" indicate that one parameter should follow.

c) calls the getopt function. The function returns two lists: opts and args.

opts is the analyzed format information. opts is a list of one tuple. Each element is :(option string, additional parameters). Empty string "" if there is no additional argument.

ops in the above example is: [(' h ', '), (' - i ', 'inputfile), (' - o', 'outputfile)]

args is the remaining command-line argument that is not part of the format information.

The third argument to the getopt function [, long_options] is an optional long option argument, with short options in the above example (e.g. -ES121en-ES122en)

Examples of long option formats:

--version
--file=error.txt

Make 1 script support both short and long options

getopt.getopt(sys.argv[1:], "hi:o:", ["version", "file="])

conclusion