Python | os.ftruncate() Method

Python The os.ftruncate() method truncates the file corresponding to file descriptor fd to a size of at most length bytes.

Syntax: os.ftruncate(fd, length)

Parameters:

fd: This is the file descriptor to be truncated.

length: This is the length of the file to be truncated.

Return Value: This method does not return any value.

Example 1

Use the os.ftruncate() method to truncate the 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 = 'GeeksforGeeks'
  
# 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

Use the os.ftruncate() method to truncate the 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 = 'GeeksforGeeks - 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'