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os module

os module

In Python, the os module is a built-in module that allows a program to interact with the operating system. It helps you perform tasks like working with files and folders, getting system information, and managing directories. It is commonly used when a Python program needs to communicate with the computer's file system. OS module comes under Python's standard utility modules.

Some important functions of the Python os module are:
  • Handling the Current Working Directory
  • Creating a Directory
  • Listing out Files and Directories with Python
  • Deleting Directory or Files using Python
  • File Permissions and Metadata
Uses of os module Working with directories (folders)

Creating new folder

import os

os.mkdir("test_folder")   # new folder 'test_folder' will be created in your current workind directory
os.rmdir("test_folder")   # test_folder will be removed a folder
Getting the current working directory 
import os
cwd = os.getcwd()
print("Current working directory: ", cwd)
Changing the directory

In certain cases, we may have to change the working directory and we can do so using os.chdir() method.

import os
cwd = os.getcwd()
print("Current working directory: ", cwd)
# chdir method will change directory. If your current working directory is d:/python/codes
os.chdir("C:/Users")
# os.chdir("C:/Users") command will change your directory to C:/Users
Listing files in a directory 
import os

os.chdir("C:/movies")
os.listdir()  # This command will display all the contents of movies directory stored in C drive
Checking if a file exists

If we want to know whether specific file exists in system or not, in that case we can use exists() method. 

import os
if os.path.exists("digger.mp4"):
    print("file exists")
else:
    print("file does not exist")
Getting system information

We can know information about the Operating system of our system using, we can use os module. For example, os.name() returns name of os used. 

import os
print("OS used in this machine: ",os.name)
Removing Directory

Suppose we have a folder named "hello" in our current working directory, we can remove folder hello using command: os.rmdir("hello")

import os
os.rmdir("hello")
print("files:",os.listdir())
Removing file

We can remove file using os.remove("filename") command.

import os
try:
    if os.path.exists("hello.csv"):  # this will check if a file exists or not
        os.remove("hello.csv")
    else:
        print("file does not exists")
    except IOError as e:
        print("file error: ",e)
File Permissions

Python os module can be used to access and change file permissions. Some of the important methods for working with file permissions are:

  • os.chmod(): used to change file or directory permissions
  • os.chown(): used to change file owner and group (Unix only)
  • os.stat(): used to fetch metadata like file size, modification time, permissions, etc.

Examples 
import os
# Set read-write permissions of file sample.txt for owner (0o600)
os.chmod("hello.txt", 0o600)

# To change ownership and group id of file os.chown() method is used.  
os.chown("hello.txt", 1000, 1000)

#To retrieve metadata about file os.stat() method is used.
stats = os.stat("hello.txt")
print("Size:", stats.st_size, "bytes")
print("Last modified:", stats.st_mtime)
print("Permissions:", oct(stats.st_mode)[-3:])
  • #0o600 is in Octal format and it means: Owner: Read & write, Group: No permission, Others: No permission
  • In os.chown() method, is use to change file ownership, parameters passed are file name, uid and gid; uid and gid must be integers. To run os.chown() method root access is required to change file ownership. os.chwon() method if used in is supported platforms like Windows, AttributeError will be raised.
  • os.stat(): we can get size of file (st_size), Last modified date: (st_mtime) and many more.