python常用模块之sys模块

1.sys.argv[]:命令行参数List,第一个元素是程序本身

# 写一个简单的python程序，代码如下：

#!/usr/bin/python

#coding=utf8

"""

Author: xiaoyafei

Created Time : 2018-05-09 14:57:36

File Name: argvTest.py

"""

import sys

print(sys.argv[0])

print(sys.argv[1])

print(sys.argv[2])

# 去执行这个程序

[root@host-10-200-137-195 tmp]# python3 argvTest.py old_str new_str

argvTest.py  # 第0个是函数本身

old_str  # 第一个

new_str  # 第二个

2.sys.exit():退出程序，正常退出是sys.exit(0)

In [1]: import sys

In [2]: sys.exit("bye")

An exception has occurred, use %tb to see the full traceback.

SystemExit: bye  # 会打印个bye然后退出

/usr/local/lib/python3.6/site-packages/IPython/core/interactiveshell.py:2918: UserWarning: To exit: use 'exit', 'quit', or Ctrl-D.

  warn("To exit: use 'exit', 'quit', or Ctrl-D.", stacklevel=1)

In [2]: sys.exit(0)

An exception has occurred, use %tb to see the full traceback.

SystemExit: 0

/usr/local/lib/python3.6/site-packages/IPython/core/interactiveshell.py:2918: UserWarning: To exit: use 'exit', 'quit', or Ctrl-D.

  warn("To exit: use 'exit', 'quit', or Ctrl-D.", stacklevel=1)

3.sys.version():获取python解释程序的版本信息

In [3]: sys.version

Out[3]: '3.6.4 (default, Mar 22 2018, 13:40:22) \n[GCC 4.8.5 20150623 (Red Hat 4.8.5-16)]'

4.sys.maxsize:最大的Int值

In [9]: sys.maxsize

Out[9]: 9223372036854775807

5.sys.path:返回模块的搜索路径，初始化时使用PYTHONPATH环境变量的值

In [10]: sys.path  # 既然是列表那就可以使用append()进行追加

Out[10]:

['',

 '/usr/local/bin',

 '/usr/local/lib/python36.zip',

 '/usr/local/lib/python3.6',

 '/usr/local/lib/python3.6/lib-dynload',

 '/usr/local/lib/python3.6/site-packages',

 '/usr/local/lib/python3.6/site-packages/pip-1.5.4-py3.6.egg',

 '/usr/local/lib/python3.6/site-packages/IPython/extensions',

 '/root/.ipython']

6.sys.platform:返回操作系统平台名称

In [11]: sys.platform

Out[11]: 'linux'

7.sys.stdout.write():标准输出

In [3]: sys.stdout.write('please:')

Out[3]: please:7

8.sys.stdin.readline()[:-1]:标准输入

In [4]: sys.stdin.readline()[:-1]  # 等待用户输入，直到\n，也可以使用read函数（会一直让用户输入）

abc

Out[4]: 'abc'

9.sys.getrecursionlimit():获取最大递归深度

In [6]: sys.getrecursionlimit()

Out[6]: 3000

10.``:修改递归最大深度

In [7]: sys.setrecursionlimit(1500)

In [8]: sys.getrecursionlimit()

Out[8]: 1500

11.sys.getdefaultencoding()：获取解释器默认编码

In [9]: sys.getdefaultencoding()  # Linux默认是UTF-8

Out[9]: 'utf-8'

12.sys.getfilesystemencoding():获取内存数据存在文件的默认编码

In [10]: sys.getfilesystemencoding()  #

Out[10]: 'utf-8'  # 指的是操作系统里的文件系统