OS Module in Python with Examples

16 Jun, 2022
The OS module in Python provides functions for interacting with the operating system. OS comes under Python’s standard utility modules. This module provides a portable way of using operating system-dependent functionality. The *os* and *os.path* modules include many functions to interact with the file system. 
Consider Current Working Directory(CWD) as a folder, where the Python is operating. Whenever the files are called only by their name, Python assumes that it starts in the CWD which means that name-only reference will be successful only if the file is in the Python’s CWD.Note: The folder where the Python script is running is known as the Current Directory. This is not the path where the Python script is located.Getting the Current working directoryTo get the location of the current working directory os.getcwd() is used. 
Example:
Python3
# Python program to explain os.getcwd() method           # importing os module import os       # Get the current working # directory (CWD) cwd = os.getcwd()       # Print the current working # directory (CWD) print("Current working directory:", cwd) 
Output:
Current working directory: /home/nikhil/Desktop/gfg
Changing the Current working directory
To change the current working directory(CWD) os.chdir() method is used. This method changes the CWD to a specified path. It only takes a single argument as a new directory path. 
Note: The current working directory is the folder in which the Python script is operating. 
Example:
Python3
# Python program to change the # current working directory         import os     # Function to Get the current  # working directory def current_path():     print("Current working directory before")     print(os.getcwd())     print()         # Driver's code # Printing CWD before current_path()     # Changing the CWD os.chdir('../')     # Printing CWD after current_path() 
Output:
Current working directory before
C:\Users\Nikhil Aggarwal\Desktop\gfg

Current working directory after
C:\Users\Nikhil Aggarwal\Desktop
 
There are different methods available in the OS module for creating a directory. These are –
os.mkdir()
os.makedirs()
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. 
Example: 
Python3
# Python program to explain os.mkdir() method   # importing os module import os   # Directory directory = "GeeksforGeeks"  # Parent Directory path parent_dir = "D:/Pycharm projects/"  # Path path = os.path.join(parent_dir, directory)   # Create the directory # 'GeeksForGeeks' in # '/home / User / Documents' os.mkdir(path) print("Directory '% s' created" % directory)   # Directory directory = "Geeks"  # Parent Directory path parent_dir = "D:/Pycharm projects"  # mode mode = 0o666  # Path path = os.path.join(parent_dir, directory)   # Create the directory # 'GeeksForGeeks' in # '/home / User / Documents' # with mode 0o666 os.mkdir(path, mode) print("Directory '% s' created" % directory) 
Output:
Directory 'GeeksforGeeks' created
Directory 'Geeks' created
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. 
Example: 
Python3
# Python program to explain os.makedirs() method       # importing os module 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                   # Leaf directory directory = "c"      # Parent Directories parent_dir = "D:/Pycharm projects/GeeksforGeeks/a/b"      # mode mode = 0o666      path = os.path.join(parent_dir, directory)       # Create the directory 'c'       os.makedirs(path, mode) print("Directory '% s' created" % directory)             # 'GeeksForGeeks', 'a', and 'b' # will also be created if # it does not exists       # If any of the intermediate level # directory is missing # os.makedirs() method will # create them       # os.makedirs() method can be # used to create a directory tree 
Output:
Directory 'Nikhil' created
Directory 'c' created
os.listdir() method in Python is used to get the list of all files and directories in the specified directory. If we don’t specify any directory, then the list of files and directories in the current working directory will be returned. 
Example:
Python3
# Python program to explain os.listdir() method       # importing os module import os   # Get the list of all files and directories # in the root directory path = "/"dir_list = os.listdir(path)   print("Files and directories in '", path, "' :")   # print the list print(dir_list) 
Output:
Files and directories in ' / ' :
['sys', 'run', 'tmp', 'boot', 'mnt', 'dev', 'proc', 'var', 'bin', 'lib64', 'usr', 
'lib', 'srv', 'home', 'etc', 'opt', 'sbin', 'media']
 
OS module proves different methods for removing directories and files in Python. These are – 
Using os.remove()
Using os.rmdir()
os.remove() method in Python is used to remove or delete a file path. This method can not remove or delete a directory. If the specified path is a directory then OSError will be raised by the method. 
Example: Suppose the file contained in the folder are: 
Python3
# Python program to explain os.remove() method       # importing os module import os       # File name file = 'file1.txt'      # File location location = "D:/Pycharm projects/GeeksforGeeks/Authors/Nikhil/"      # Path path = os.path.join(location, file)       # Remove the file # 'file.txt' os.remove(path) 
Output:
os.rmdir() method in Python is used to remove or delete an empty directory. OSError will be raised if the specified path is not an empty directory. 
Example: Suppose the directories are 
Python3
# Python program to explain os.rmdir() method       # importing os module import os       # Directory name directory = "Geeks"      # Parent Directory parent = "D:/Pycharm projects/"      # Path path = os.path.join(parent, directory)       # Remove the Directory # "Geeks" os.rmdir(path) 
Output:
 
1. 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’.
Python3
import os  print(os.name)
Output:
posix
Note: It may give different output on different interpreters, such as ‘posix’ when you run the code here. 
2. os.error: All functions in this module raise OSError in the case of invalid or inaccessible file names and paths, or other arguments that have the correct type, but are not accepted by the operating system. os.error is an alias for built-in OSError exception. 
Python3
import os    try:    # If the file does not exist,    # then it would throw an IOError    filename = 'GFG.txt'    f = open(filename, 'rU')    text = f.read()    f.close()  # Control jumps directly to here if # any of the above lines throws IOError.    except IOError:      # print(os.error) will <class 'OSError'>    print('Problem reading: ' + filename)      # In any case, the code then continues with # the line after the try/except
Output: 
Problem reading: GFG.txt
 3. os.popen(): This method opens a pipe to or from command. The return value can be read or written depending on whether the mode is ‘r’ or ‘w’. Syntax: 
 os.popen(command[, mode[, bufsize]])
Parameters mode & bufsize are not necessary parameters, if not provided, default ‘r’ is taken for mode. 
Python3
import osfd = "GFG.txt"  # popen() is similar to open()file = open(fd, 'w')file.write("Hello")file.close()file = open(fd, 'r')text = file.read()print(text)  # popen() provides a pipe/gateway and accesses the file directlyfile = os.popen(fd, 'w')file.write("Hello")# File not closed, shown in next function.
Output: 
Hello
Note: Output for popen() will not be shown, there would be direct changes into the file. 
4. os.close(): Close file descriptor fd. A file opened using open(), can be closed by close()only. But file opened through os.popen(), can be closed with close() or os.close(). If we try closing a file opened with open(), using os.close(), Python would throw TypeError. 
Python3
import os    fd = "GFG.txt"file = open(fd, 'r')text = file.read()print(text)os.close(file)
Output: 
Traceback (most recent call last):
  File "C:\Users\GFG\Desktop\GeeksForGeeksOSFile.py", line 6, in 
    os.close(file)
TypeError: an integer is required (got type _io.TextIOWrapper)
Note: The same error may not be thrown, due to the non-existent file or permission privilege. 
5. os.rename(): A file old.txt can be renamed to new.txt, using the function os.rename(). The name of the file changes only if, the file exists and the user has sufficient privilege permission to change the file.
Python
import os    fd = "GFG.txt"os.rename(fd,'New.txt')os.rename(fd,'New.txt')
Output:
Traceback (most recent call last):
  File "C:\Users\GFG\Desktop\ModuleOS\GeeksForGeeksOSFile.py", line 3, in 
    os.rename(fd,'New.txt')
FileNotFoundError: [WinError 2] The system cannot find the
file specified: 'GFG.txt' -> 'New.txt'
Understanding the Output: A file name “GFG.txt” exists, thus when os.rename() is used the first time, the file gets renamed. Upon calling the function os.rename() second time, file “New.txt” exists and not “GFG.txt” thus Python throws FileNotFoundError.  
6. os.remove(): Using the Os module we can remove a file in our system using the remove() method. To remove a file we need to pass the name of the file as a parameter. 
Python3
import os #importing os module.  os.remove("file_name.txt") #removing the file.
The OS module provides us a layer of abstraction between us and the operating system. When we are working with os module always specify the absolute path depending upon the operating system the code can run on any os but we need to change the path exactly. If you try to remove a file that does not exist you will get FileNotFoundError. 
7. os.path.exists(): This method will check whether a file exists or not by passing the name of the file as a parameter. OS module has a sub-module named PATH by using which we can perform many more functions. 
Python3
import os #importing os module  result = os.path.exists("file_name") #giving the name of the file as a parameter.  print(result)
False
As in the above code, the file does not exist it will give output False. If the file exists it will give us output True. 
8. 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.
Python3
import os #importing os module  size = os.path.getsize("filename")  print("Size of the file is", size," bytes.")
Output:
Size of the file is 192 bytes.
This article is contributed by Piyush Doorwar. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
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