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) 