Python3 中使用sys.argv详解

#/usr/bin/env python
#coding:utf-8

import sys
# print(sys.argv[1])
def readFile(filename):
    """定义readFile函数，从文件中读出文件内容"""
    with open(filename) as f:
        while True:
            line = f.readline()
            if len(line) == 0:
                break
            print(line)

print(sys.argv)
if len(sys.argv) < 2:
    print('No action specified')
    sys.exit()
if sys.argv[1].startswith('--'):
    option = sys.argv[1][2:]
    # fetch sys.argv[1] but without the first two characters,索引为2开始，往后取所有
    if option == 'version':#当命令行参数为-- version，显示版本号
        print('version 1.2')
    elif option == 'help': #当命令行参数为--help时，显示相关帮助内容
        print("""
        This program prints files to the standard output.
Any number of files can be specified.
Options include:
  --version : Prints the version number
  --help    : Display this help'
        """)
    else:
        print('Unknow option')
    sys.exit()

else:
    for filename in sys.argv[1:]:#当参数为文件名时，传入readfile，读出其内容
        readFile(filename)