Python os.write() Method

1. Syntax of os.write() Method
2. Example 1: Use os.write() Method to Write a Byte-String to a Given File Descriptor
3. Example 2: Alternative Syntax of the os.write() Method
4. Example 3: Use the os.fdopen Method With the os.write() Method

Python os.write() method is an efficient way of writing a byte of string to a specific file descriptor.

Syntax of os.write() Method

os.write(fd, string)

Parameters

Return

The return type of this method is an integer value representing the number of bytes written successfully on a file.

Example 1: Use os.write() Method to Write a Byte-String to a Given File Descriptor

import os

fd = os.open( "File.txt", os.O_RDWR|os.O_CREAT )

bytes=os.write(fd, 'Hello, World!'.encode())

os.close( fd )

print("The number of bytes written is:", bytes)

print ("The file has been closed successfully!")

Output:

The number of bytes written is: 13
The file has been closed successfully!

The methods os.open() and os.write() go hand in hand because one has to open a file and write data. Data can’t be written into a file in another way.

Example 2: Alternative Syntax of the os.write() Method

import os

file = open("File.txt", "w")

file.write("Hello, World!")

file.close()

file = open("File.txt", "r")

print(file.read())

Output:

Hello, World!

It is a healthy practice for any programmer to close all the newly opened files using the os.close() method.

Example 3: Use the os.fdopen Method With the os.write() Method

import os

with os.fdopen(os.open("File.txt",os.O_CREAT | os.O_RDWR ),'w') as fd:
    fd.write("Hello, World!")

print ("The file descriptor has been closed successfully.")

Output:

The file descriptor has been closed successfully.

Note that the returned file descriptor from this method is non-inheritable.