内置模块：sys模块

sys模块：
 1. sys.argv()     #命令行参数list,第一个参数是程序的本身路径
  test.py
  
  import sys
  print(sys.argv)
  
  >> python test.py 11212 11212,1211as
  ['test.py', '11212', '11212,1211as']
  
  
 2. sys.exit(n)     #退出程序，正常退出时exit(0)
 
 
 3. sys.version     #解释器的版本
  >>> sys.version
  '3.6.5 (v3.6.5:f59c0932b4, Mar 28 2018, 16:07:46) [MSC v.1900 32 bit (Intel)]'
  
 4. sys.path     #模块的path环境变量
  >>> sys.path
  ['', 'D:\Python3\python_project\Project_1\venv\Scripts\python36.zip', 'C:\Users\brace.li\AppData\Local\Programs
  Python\Python36-32\DLLs', 'C:\Users\brace.li\AppData\Local\Programs\Python\Python36-32\lib', 'C:\Users\brace.l
  i\AppData\Local\Programs\Python\Python36-32', 'D:\Python3\python_project\Project_1\venv', 'D:\Python3\python_pro
  ject\Project_1\venv\lib\site-packages', 'D:\Python3\python_project\Project_1\venv\lib\site-packages\setuptools-3
  9.0.1-py3.6.egg', 'D:\Python3\python_project\Project_1\venv\lib\site-packages\pip-9.0.3-py3.6.egg']

 5. sys.platform    #返回系统平台
  >>> sys.platform
  'win32'
  
 6. sys.stdout.write("ss")   #标准输出
  
  进度条的使用：
  import sys,time
  for i in range(100):
   sys.stdout.write("#")
   sys.stdout.flush()
   time.sleep(0.1)