Learn about common modules that Python must know

A program or subroutine required to complete a function in a program, or a stand-alone program unit that can be processed by a compiler, assembly, etc., or part of a large software system. This article introduces you to two common modules in Python.

Os

This module contains common operating system functions. This module can be used to write platform-independent programs, such as using OS.SEP to replace operating system-specific path separators.

List some of the methods commonly used in OS modules:

Os.name: Gets the current system platform, Windows returns ' NT ', and Linux returns ' POSIX '.

OS.LINESEP: Gets the line terminator used by the current platform. Windows returns '/r/n ', Linux uses '/n '.

OS.GETCWD (): Gets the current working directory, which is the directory path of the current Python script work.

Os.listdir (PATH): Returns all file and directory names under the specified directory.

For example:

Python code

1	>>> os.listdir(‘/home/shirley/‘)

The Os.remove (path/filename) function is used to delete a file.

The Os.system () function is used to run the shell command. This command makes it easy to invoke or execute other scripts and commands

For example:

Python code

1234	#打开记事本  >>>os.system(‘notepad‘)  #打开指定的文件  >>>os.system(‘notepad shirley_python.txt‘)

The Os.path.split () function returns the directory name and file name of a path.

For example:

Python code

12	>>> os.path.split(‘/home/shirley/myself/code/icbc.txt‘)  (‘/home/shirley/myself/code‘, ‘icbc.txt‘)

The Os.path.isfile () and Os.path.isdir () functions respectively verify that the given path is a file or a directory.

Similarly, the Os.path.existe () function is used to verify that the given path really exists.

Sys

The SYS module has many functions and can be referred to in Python document Http://docs.python.org/library/sys.html.

To enumerate the usage of some commonly used functions:

SYS.ARGV: Implements passing parameters from outside the program to the program.

For example:

The contents of the print.py script are:

Python code

1234	importsys print sys.argv[0]  print sys.argv[1]  printsys.argv[2]

Execute in the Interpreter:

Python code

1	>>>python print.py arg1 arg2

In general, Argv[0] represents the file name of the executed program, i.e. print.py,argv[1],argv[2] corresponding to the ARG1,ARG2 in the Interpreter command respectively.

Sys.exit ([arg]): Exit in the middle of the program, arg=0 for normal exit.

Sys.getdefaultencoding (): Gets the system current encoding, which is generally ASCII by default.

Sys.setdefaultencoding (): Set system default encoding, do not see this method when executing dir (SYS), do not pass in interpreter, can execute reload (SYS), execute setdefaultencoding (' UTF8 ' ), the system default encoding is set to UTF8. (See Set system default encoding)

Sys.getfilesystemencoding (): Gets the file system using encoding, returns ' MBCS ' under Windows, and returns ' Utf-8 ' under Mac.

Sys.path: Gets a collection of strings for the specified module search path, which can be placed in a given path, and can be found correctly when import is in the program.

Sys.platform: Gets the current system platform.

Learn about common modules that Python must know