Friday, November 21, 2025
HomeLanguagesPython | os.ftruncate() method

Python | os.ftruncate() 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.ftruncate() method truncates the file corresponding to file descriptor fd, so that it is at most length bytes in size.

Syntax: os.ftruncate(fd, length)

Parameters:
fd: This is the file descriptor that is to be truncated.
length: This is the length of the file upto which file is to be truncated.

Return Value: This method does not returns any value.

Example #1 :
Using os.ftruncate() method to truncate a file




# Python program to explain os.ftruncate() method 
        
# importing os module 
import os 
    
# path 
path = 'C:/Users/Rajnish/Desktop/testfile.txt'
  
# Open the file and get
# the file descriptor associated
# with it using os.open() method
fd = os.open(path, os.O_RDWR|os.O_CREAT)
  
# String to be written
s = 'neveropen'
  
# Convert the string to bytes 
line = str.encode(s)
  
# Write the bytestring to the file 
# associated with the file 
# descriptor fd 
os.write(fd, line)
  
# Using os.ftruncate() method
os.ftruncate(fd, 5)
  
# Seek the file from beginning
# using os.lseek() method
os.lseek(fd, 0, 0)
  
# Read the file
s = os.read(fd, 15)
  
# Print string
print(s)
  
# Close the file descriptor 
os.close(fd)


Output:

b'Geeks'

Example #2 :
Using os.ftruncate() method to truncate a file




# Python program to explain os.ftruncate() method 
        
# importing os module 
import os 
    
# path 
path = 'C:/Users/Rajnish/Desktop/testfile.txt'
  
# Open the file and get
# the file descriptor associated
# with it using os.open() method
fd = os.open(path, os.O_RDWR|os.O_CREAT)
  
# String to be written
s = 'neveropen - Computer Science portal'
  
# Convert the string to bytes 
line = str.encode(s)
  
# Write the bytestring to the file 
# associated with the file 
# descriptor fd 
os.write(fd, line)
  
# Using os.ftruncate() method
os.ftruncate(fd, 10)
  
# Seek the file from beginning
# using os.lseek() method
os.lseek(fd, 0, 0)
  
# Read the file
s = os.read(fd, 15)
  
# Print string
print(s)
  
# Close the file descriptor 
os.close(fd)


Output:

b'GeeksforGe'
Last Updated :
25 Jun, 2019
Like Article
Save Article

<!–

–>

Similar Reads
Related Tutorials
Dominic
Dominichttp://wardslaus.com
infosec,malicious & dos attacks generator, boot rom exploit philanthropist , wild hacker , game developer,
RELATED ARTICLES

Most Popular

Dominic
32405 POSTS0 COMMENTS
Milvus
97 POSTS0 COMMENTS
Nango Kala
6781 POSTS0 COMMENTS
Nicole Veronica
11928 POSTS0 COMMENTS
Nokonwaba Nkukhwana
11997 POSTS0 COMMENTS
Shaida Kate Naidoo
6907 POSTS0 COMMENTS
Ted Musemwa
7166 POSTS0 COMMENTS
Thapelo Manthata
6862 POSTS0 COMMENTS
Umr Jansen
6847 POSTS0 COMMENTS