[系統互動篇] 如何從系統命令列，讀取輸入的參數 - tsungjung411/python-study GitHub Wiki

python get parameter from cmd

傳統方式讀取

import sys
print(sys.argv)

• How do I access command line arguments in Python?

Argparse 教學

用來解析輸入參數的套件，不用在自己去硬刻剖析器

官方範例

• test.py

  import argparse
  parser = argparse.ArgumentParser()
  parser.parse_args()
  

• 執行測試

  $python test.py --help
  usage: test.py [-h]
  
  optional arguments:
    -h, --help  show this help message and exit
  

位置參數用法

• 介紹位置參數

  import argparse
  parser = argparse.ArgumentParser()
  parser.add_argument("echo")
  args = parser.parse_args()
  print(args.echo)
  

如何顯示多行的程式說明？

• test.py

  import argparse
  parser = argparse.ArgumentParser(description='''
  This is a sample for argument parser.
  
  If you want to show multiple lines, 
  you need to use 'RawTextHelpFormatter'
  ''', formatter_class=argparse.RawTextHelpFormatter)
  args = parser.parse_args()
  

• 執行結果(使用RawTextHelpFormatter)

  $ python test.py -h
  usage: test.py [-h]
  
  This is a sample for argument parser.
  
  If you want to show multiple lines,
  you need to use 'RawTextHelpFormatter'
  
  optional arguments:
    -h, --help  show this help message and exit
  

• 執行結果(不使用RawTextHelpFormatter)

  $ python test.py -h
  usage: test.py [-h]
  
  This is a sample for argument parser. If you want to show multiple lines, you need to use 'RawTextHelpFormatter'
  
  optional arguments:
    -h, --help  show this help message and exit
  

如何同時允許「短參數(-v)」和「長參數(--verbose)」

• test.py

  import argparse
  parser = argparse.ArgumentParser()
  parser.add_argument('-v', '--verbose', help="increase output verbosity", action="store_true")
  print('parser:', parser)
  args = parser.parse_args()
  print('args:', args)
  

• 執行結果

  $ python test.py -v
  $ python test.py --verbose
  ('parser:', ArgumentParser(prog='test.py', usage=None, description=None, version=None, formatter_class=<class 'argparse.HelpFormatter'>, conflict_handler='error', add_help=True))
  ('args:', Namespace(verbose=True))
  

如何允許未知參數的輸入，以及如何重導指令

• test.py

  import argparse
  parser = argparse.ArgumentParser()
  parser.add_argument('--verbose', help="increase output verbosity", action="store_true")
  print('parser:', parser)
  
  args, unknown_args = parser.parse_known_args()
  print('args:', args)
  print('unknown_args:', unknown_args)
  
  import os
  os.system('echo ' + ' '.join(unknown_args))
  

• 執行結果

  $ python test.py -msg 'hello' -msg 'hi' --message="long message"
  ('parser:', ArgumentParser(prog='test.py', usage=None, description=None, version=None, formatter_class=<class 'argparse.HelpFormatter'>, conflict_handler='error', add_help=True))
  ('args:', Namespace(verbose=False))
  ('unknown_args:', ['-msg', 'hello', '-msg', 'hi', '--message=long message'])
  
  -msg hello -msg hi --message=long message