Python | os.truncate() 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.truncate() method in Python is used to truncate the file indicated by the specified path to at most specified length.

Syntax: os.truncate(path, length)

Parameters:
path: A path-like object representing a file system path. This will indicate the file to be truncated.
A path-like object is either a string or bytes object representing a path.
length: An integer value denoting length (in bytes) to which the file is to be truncated.

Return Type: This method does not return any value.

Consider the below text as the content of the file named Python_intro.txt.

Python is a widely used general-purpose, high level programming language. It was initially designed by Guido van Rossum in 1991 and developed by Python Software Foundation. It was mainly developed for emphasis on code readability, and its syntax allows programmers to express concepts in fewer lines of code. Python is a programming language that lets you work quickly and integrate systems more efficiently.

Code #1: Use of os.truncate() method

# Python program to explain os.truncate() method

# importing os module
import os

# File path
path = "/home / ihritik / Desktop / Python_intro.txt"

# Print the original size of the file (in bytes)
print("File size (in bytes):", os.path.getsize(path))

# Length (in Bytes) to which
# the file will be truncated
length = 72

# Truncate the file
# to at most given length
# using os.truncate() method
os.truncate(path, length)

# Print the content of file
print("Content of file Python_intro.txt:")
with open(path, 'r') as f:
    print(f.read())

# Print the new size of the file (in bytes)
print("File size (in bytes):", os.path.getsize(path))

Output:

File size (in bytes): 409
Content of file Python_intro.txt:
Python is a widely used general-purpose, high level programming language
File size (in bytes): 72

Consider the below text as the new content of the file named Python_intro.txt.

Python is a widely used general-purpose, high level programming language

Code #2: If the specified length exceeds the file size

# Python program to explain os.truncate() method

# importing os module
import os

# File path
path = "/home / ihritik / Desktop / Python_intro.txt"

# Print the original size of the file (in bytes)
print("File size (in bytes):", os.path.getsize(path))

# Length (in Bytes) to which
# the file will be truncated
length = 72

# Truncate the file
# to at most given length
# using os.truncate() method
os.truncate(path, length)

# Print the content of file
print("Content of file Python_intro.txt:")
with open(path, 'r') as f:
    print(f.read())

# Print the new size of the file (in bytes)
print("File size (in bytes):", os.path.getsize(path))

Output:

File size (in bytes): 72
Content of file Python_intro.txt:
Python is a widely used general-purpose, high level programming language

File size (in bytes): 100

Actual file content after truncating file sized 72 bytes to 100 bytes:

The file content up to its original size did not changed but to increase the file size to the specified size it got filled with some invalid characters.

Code #3: Deleting a file content using os.truncate() method

# Python program to explain os.truncate() method

# importing os module
import os

# File path
path = "/home / ihritik / Desktop / Python_intro.txt"

# Print the original size of the file (in bytes)
print("File size (in bytes):", os.path.getsize(path))

# specify the length as 0
# to delete the file content
length = 0

# Truncate the file
# to length 0
os.truncate(path, length)

# Print the content of file
print("Content of file Python_intro.txt:")
with open(path, 'r') as f:
    print(f.read())

# Print the new size of the file (in bytes)
print("File size (in bytes):", os.path.getsize(path))

# Consider the same Python_intro.txt file
# used in above example for this example

Output:

File size (in bytes): 100
Content of file Python_intro.txt:

File size (in bytes): 0