46 - OS Modules

OS Module in Python

Summary

The os module in Python is a built-in library that provides a wide variety of functions for interacting with the operating system.
It allows you to perform tasks such as reading and writing files, interacting with the file system, and running system commands.

The os module in Python is a built-in library that provides functions for interacting with the operating system.
It allows you to perform a wide variety of tasks, such as reading and writing files, interacting with the file system, and running system commands.

Here are some common tasks you can perform with the os module:

Interacting with the file system:-

The os module also provides functions for interacting with the file system.

os.getcwd( ):-

Get the current working directory.

import os          

#directory (CWD)
cwd = os.getcwd()

print("Current working directory:", cwd)

------
# Output:-
Current working directory: /home/nikhil/Desktop/gfg

os.chdir( )

Changing the Current Working Directory

import os

os.chdir('../') # changing dir 

------
# Output:-

#Current working directory before
C:\Users\Nikhil Aggarwal\Desktop\gfg

#Current working directory now
C:\Users\Nikhil Aggarwal\Desktop

os.listdir( ):-

you can use the os.listdir function to get a list of the files in a directory:

import os

# Get a list of the files in the current directory
files = os.listdir(".")
print(files)   

------
# Output:-

['myfile.txt', 'otherfile.txt']

Create directory :-

There are different methods available in the OS module for creating a directory.

os.mkdir( ):-

os.mkdir() method in Python is used to create a directory named path with the specified numeric mode.
This method raises FileExistsError if the directory to be created already exists.

import os

# Create a new directory
os.mkdir("newdir")

------
# Output:-

Directory 'newdir' created

os.makedirs( ):-

os.makedirs() method in Python is used to create a directory recursively.
That means while making leaf directory if any intermediate-level directory is missing, os.makedirs() method will create them all.
os.makedirs() method can be used to create a directory tree.

import os
	
# Leaf directory
directory = "Nikhil"	
# Parent Directories
parent_dir = "D:/Pycharm projects/GeeksForGeeks/Authors"
# Path
path = os.path.join(parent_dir, directory)
	
# Create the directory 'Nikhil'
os.makedirs(path)
print("Directory '% s' created" % directory)
	
# Directory 'GeeksForGeeks' and 'Authors' will
# be created too
# if it does not exists

------
# Output:-

Directory 'Nikhil' created

os.remove( ):-

This method is used to delete files.
This method can not remove or delete a directory.
If the specified path is a directory then OS Error will be raised.

import os 


# File name 
file='file1.txt'
location="D:/Pycharm projects/GeeksforGeeks/Authors/Nikhil/"

os.remove(file)

------
# Output:-

file.txt deleted

os.rmdir( ):-

This method is used to delete directories or folders.
This method cann't delete non-empty directories.
OSError will be raised if the specified path is not an empty directory.

“Pasted image 20230810162932.png” could not be found.

# Python program to explain os.rmdir() method
	
# importing os module
import os
	
# Remove the Directory "Geeks"
os.rmdir(Geeks)

Reading and writing files

The os module provides functions for opening, reading, and writing files. For example, to open a file for reading, you can use the open function:

os.read( ) & os.RDONLY flag:-

Read the contents of the file

import os

# Open the file in read-only mode
f = os.open("myfile.txt", os.O_RDONLY)

# Read the contents of the file
contents = os.read(f, 1024)

# Close the file
os.close(f)

os.read & os.O_WRONLY flag:

import os

# Open the file in write-only mode
f = os.open("myfile.txt", os.O_WRONLY)

# Write to the file
os.write(f, b"Hello, world!")

# Close the file
os.close(f)

OS.rename( ):-

Rename files/directories.
The file/directories have to exist.

“Pasted image 20230810191537.png” could not be found.

import os

for i in range(0,11):
os.rename(f'data/Day{i+1}', f"data/Tutorial{i+1}") # rename directories with a loop 
#          input folders   ,   new names
  • Output:-

    “Pasted image 20230810191720.png” could not be found.

OS.remove( ):-

Using the Os module we can remove a file in our system using the remove() method.

import os #importing os module.

os.remove("file_name.txt") #removing the file.
Info

OS module has a sub-module named PATH by using which we can perform many more functions.

OS.path.exists( ):-

This method will check whether a file exists or not by passing the name of the file as a parameter

import os

result = os.path.exists("file_name") #giving the name of the file as a parameter.
print(result)


# output:-
False

OS.path.getsize( ):-

In this method, python will give us the size of the file in bytes. To use this method we need to pass the name of the file as a parameter.

import os

size = os.path.getsize("filename")
print("Size of the file is", size," bytes.")


# Output:-
Size of the file is 192 bytes.

Running system commands

Finally, the os module provides functions for running system commands.

OS.system("<Command_name>"):-

You can use the os.system("<Command_name>") function to run a command and get the output:

import os
# Run the "ls" command and print the output
output = os.system("ls")
print(output)  


# Output: ['myfile.txt', 'otherfile.txt']

os.popen( ):-

You can use the os.popen function to run a command and get the output as a file-like object:

import os

# Run the "ls" command and get the output as a file-like object
f = os.popen("ls")

# Read the contents of the output
output = f.read()
print(output)  
# Output: 
# ['myfile.txt', 'otherfile.txt']

# Close the file-like object
f.close()

misc:-

OS.name( ):-

This function gives the name of the operating system dependent module imported.
The following names have currently been registered: ‘posix’, ‘nt’, ‘os2’, ‘ce’, ‘java’ and ‘riscos’.

import os

print(os.name)  # output: posix

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