第3章：打造命令行工具

import sys
print(sys.argv)

import sys
def get_content():
    return sys.stdin.readlines()
print(get_content())
使用Ctrl+d退出

fileinput的使用非常简单，大部分情况下，我们直接调用fileinput模块的input方法按行读取内容即可
用for循环遍历文件内容
# cat read_from_fileinput.py 
from __future__ import print_function
import fileinput

for line in fileinput.input():
    print(line, end=" ")

# cat /etc/passwd | python read_from_fileinput.py

import getpass
user = getpass.getuser()
passwd = getpass.getpass(‘your password: ‘)
print(user,passwd)

import configparser
cf = configparser.ConfigParser(allow_no_value=True)
cf.read(‘/etc/my.cnf‘)
print(cf.sections())
print(cf.has_section(‘client‘))
print(cf.options(‘client‘))
print(cf.has_option(‘client‘,‘user‘))
print(cf.get(‘client‘,‘user‘))

import argparse

def _argparse():
    parser = argparse.ArgumentParser(description="This is description")
    parser.add_argument(‘--host‘, action=‘store‘, dest=‘server‘, default="localhost", help=‘connect to host‘)
    parser.add_argument(‘-t‘, action=‘store_true‘, dest=‘boolean_switch‘, default=False, help=‘Set a switch to true‘)
    return parser.parse_args()

def main():
    parser = _argparse()
    print(parser)
    print(‘host = ‘, parser.server)
    print(‘boolean_switch = ‘, parser.boolean_switch)

if __name__ == ‘__main__‘:
    main()

import argparse

def _argparse():
    parser = argparse.ArgumentParser(description=‘A Python-MySQL client‘)
    parser.add_argument(‘--host‘, action=‘store‘, dest=‘host‘, required=True, help=‘connect to host‘)
    parser.add_argument(‘-u‘, ‘--user‘, action=‘store‘, dest=‘user‘, required=True, help=‘user for login‘)
    parser.add_argument(‘-p‘, ‘--password‘, action=‘store‘, dest=‘password‘, required=True, help=‘password to use when connecting to server‘)
    parser.add_argument(‘-P‘, ‘--port‘, action=‘store‘, dest=‘port‘, default=3306, type=int, help=‘port number to use for connection or 3306 for default‘)
    parser.add_argument(‘-v‘, ‘--version‘, action=‘version‘, version=‘%(prog)s 0.1‘)
    return parser.parse_args()

def main():
    parser = _argparse()
    conn_args = dict(host=parser.host, user=parser.user, password=parser.password, port=parser.port)
    print(conn_args)

if __name__ == ‘__main__‘:
    main()

import logging

logging.debug(‘debug message‘)
logging.info(‘info message‘)
logging.warn(‘warn message‘)
logging.error(‘error message‘)
logging.critical(‘critical message‘)