sys module of python common modules

sys module of python common modules

1. sys.argv[]: List of command line parameters, the first element is the program itself

# 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(): Exit the program, the normal exit is 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(): Get the version information of the python interpreter

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: Maximum Int value

In [9]: sys.maxsize
Out[9]: 9223372036854775807

5. sys.path: Returns the search path of the module, using the value of the PYTHONPATH environment variable during initialization

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: Returns the operating system platform name

In [11]: sys.platform
Out[11]: 'linux'

7. sys.stdout.write(): stdout

In [3]: sys.stdout.write('please:')
Out[3]: please:7

8. sys.stdin.readline()[:-1]: Standard input

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(): Get the maximum recursion depth

In [6]: sys.getrecursionlimit()
Out[6]: 3000

10. ``: Modify the maximum depth of recursion

In [7]: sys.setrecursionlimit(1500)

In [8]: sys.getrecursionlimit()
Out[8]: 1500

11. sys.getdefaultencoding(): Get the interpreter default encoding

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

12. sys.getfilesystemencoding(): Get the default encoding of the file stored in the memory data

In [10]: sys.getfilesystemencoding()
Out[10]: 'utf-8'