The difference between OS and sys two modules in Python

official explanations of <os and sys >

? OS

Os:this module provides a portable the by using operating system dependent functionality.

This module provides a convenient way to use the operating system functions.

? SYS

Sys:this module provides access to some variables used or maintained by the interpreter and to functions that interact St Rongly with the interpreter.

This module allows access to variables used or maintained by the interpreter and functions that interact with the interpreter.

? Summary

The OS module is responsible for the interaction between the program and the operating system, provides access to the underlying interface of the operating system, and the SYS module is responsible for the interaction between the program and the Python interpreter, providing a series of functions and variables for manipulating the Python runtime environment.

<os Common Methods >

Os.remove (' path/filename ') Delete file

Os.rename (Oldname, newname) renaming files

Os.walk () Generate all file names under the directory tree

Os.chdir (' dirname ') Change directory

Os.mkdir/makedirs (' dirname ') create a directory/multi-level directory

Os.rmdir/removedirs (' dirname ') Delete directory/multi-level directory

Os.listdir (' dirname ') lists the files for the specified directory

OS.GETCWD () Get the current working directory

Os.chmod () Changing directory permissions

Os.path.basename (' path/filename ') remove directory path, return file name

Os.path.dirname (' path/filename ') remove file name, return directory path

Os.path.join (path1[,path2[,...]]) combines the parts of the separation into one path name

Os.path.split (' path ') returns (DirName (), basename ()) tuple

Os.path.splitext () return (filename, extension) tuple

Os.path.getatime\ctime\mtime returns the last access, creation, modification time, respectively

Os.path.getsize () returns the file size

Os.path.exists () is present

Os.path.isabs () is an absolute path

Os.path.isdir () is a directory

Os.path.isfile () is a file

<sys Common Methods >

SYS.ARGV command line argument list, the first element is the path of the program itself

Sys.modules.keys () returns the list of all modules that have been imported

Sys.exc_info () Gets the exception class currently being processed, Exc_type, Exc_value, exc_traceback the exception details currently handled

Sys.exit (n) exit program, Exit normally (0)

Sys.hexversion gets the version value of the Python interpreter, 16 binary format such as: 0x020403f0

Sys.version get version information for Python interpreter

Sys.maxint the largest int value

Sys.maxunicode the largest Unicode value

Sys.modules returns the module field of the system import, key is the module name, value is the module

Sys.path returns the search path for the module, using the value of the PYTHONPATH environment variable when initializing

Sys.platform returns the operating system platform name

Sys.stdout Standard Output

Sys.stdin Standard input

Sys.stderr Error Output

Sys.exc_clear () to clear current or recent error messages that are present on the current thread

Sys.exec_prefix returns the location of the platform standalone Python file installation

Sys.byteorder The local byte rule indicator, the value of the Big-endian platform is ' big ', the value of the Little-endian platform is ' little '

Sys.copyright record python copyright-related things

API version of C for the Sys.api_version interpreter

Sys.stdin,sys.stdout,sys.stderr

stdin, stdout, and stderr variables contain stream objects that correspond to standard I/O streams . If you need more control over the output, and print does not meet the requirements , they are required. You can also Replace them, and you can redirect output and input to other devices, or handle them in a non-standard way

import syssys.stdout.write(‘HelloWorld!‘)print ‘Please enter yourname:‘,name=sys.stdin.readline()[:-1]print ‘Hi, %s!‘ % name

Print and raw_input are commonly used for input and printing, so how print and raw_input relate to standard input/output streams: In fact, the standard input/output/error stream of a Python program is defined in the SYSModule, respectively: Sys.stdin,sys.stdout, Sys.stderr
The following programs can also be used to input and output the same, enter the following code in the Python Runtime environment:

import sysfor f in (sys.stdin,sys.stdout, sys.stderr): print f

the output is:

<open file‘<stdin>‘, mode ‘r‘ at 892210><open file‘<stdout>‘, mode ‘w‘ at 892270><open file‘<stderr>‘, mode ‘w at 8922d0>

It can be seen that stdin, stdout, stderr in Python is nothing more than the object of the file attributes , when they start in Pythonautomaticallyassociated with standard input, output, and error in the shell environment.
The I/O redirection of the Python program in the shell is exactly the same as the DOS command at the beginning of this article, which is actually provided by the shell and is not related to python itself. Then we can redirect the Stdin,stdout,stderr read-write operation inside the Python program to an internal object.
python provides a stringio module to complete this idea, such as:

from StringIO import StringIOimport sysbuff =StringIO()temp =sys.stdout                              #保存标准I/O流sys.stdout =buff                                #将标准I/O流重定向到buff对象print 42, ‘hello‘, 0.001sys.stdout=temp                                #恢复标准I/O流print buff.getvalue()

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The difference between OS and sys two modules in Python