Python | os.open() method
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.
os.open() method in Python opens a specified file path. This method returns a file descriptor for a newly opened file. The returned file descriptor is non-inheritable.
os.open method is also used to set various flags according to the specified flags and file’s mode according to the specified mode.
Syntax:
os.open(path, flags, mode = 0o777, *, dir_fd = None)
Parameters:
- Path: A path-like object representing the file system path. This is the file path to be opened. A path-like object is a string or bytes object which represents a path.
- flags: This parameter specifies the flags to be set for newly opened files.
- mode (optional): A numeric value representing the mode of the newly opened file. The default value of this parameter is 0o777 (octal).
- dir_fd (optional): A file descriptor referring to a directory.
Return Type:
This method returns a file descriptor for a newly opened file.
List of flags that you can set on the new file:
List of Flags | |
|---|---|
| Flag | Description |
| os.O_RDONLY | Opens the file in read-only mode. |
| os.O_WRONLY | Opens the file in write-only mode. |
| os.O_RDWR | Opens the file in read and write mode. |
| os.O_NONBLOCK | Opens the file in non-blocking mode. |
| os.O_APPEND | Opens the file and places the cursor at the end of the contents. |
| os.O_CREAT | Creates a file if it doesn’t exist. |
| os.O_TRUNC | Truncates a file size to 0. |
| os.O_EXCL | Shows an error while creating a file that already exists. |
| os.O_SHLOCK | Obtains a shared lock for a file atomically. |
| os.O_EXLOCK | Obtains an exclusive lock for a file atomically. |
| os.O_DIRECT | Removes or reduces cache effects in a file. |
| os.O_FSYNC | Writes file synchronously. |
| os.O_NOFOLLOW | Sets the file that doesn’t follow a symlink. |
How to use the os.open() method
We will use the os.open() method to open a file path. Look at the code below to understand it better:
Code:
# importing os module
import os
# File path to be opened
path = './file9.txt'
# Mode to be set
mode = 0o666
# flags
flags = os.O_RDWR | os.O_CREAT
fd = os.open(path, flags, mode)
print("File path opened successfully.")
str = "w3wiki: A computer science portal for Beginner."
os.write(fd, str.encode())
print("String written to the file descriptor.")
# Now read the file from beginning
os.lseek(fd, 0, 0)
str = os.read(fd, os.path.getsize(path))
print("\nString read from the file descriptor:")
print(str.decode())
# Close the file descriptor
os.close(fd)
print("\nFile descriptor closed successfully.")
Output
File path opened successfully. String written to the file descriptor. String read from file descriptor: w3wiki: A computer science portal for Beginner. File descriptor closed successfully.
In this tutorial, we have covered the os.open() method of the OS module to open a file. It is a very easy and straightforward way of opening files in Python.
We have explained how to use os.open() method with a sample Python program. This easy and simple tutorial will help you implement the os.open() method in your codes.
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