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What is the os.truncate() method in Python?

Salman Yousaf

Grokking Modern System Design Interview for Engineers & Managers

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Overview

The OS module in Python provides an interface to utilize the functionality of the underlying operating system.

The os.truncate() method allows us to shorten the size of the file to the given length. It reduces the size of the file from the top.

Syntax


# Signature
os.truncate(file ,length)

Parameters

It takes the following argument values.

  • file: This is the file descriptor of the directory or the file to be truncated.
  • length: This is the length of the file to which it is to be truncated.

Return value

By default, it does not return any value.

Code

In the below example, we have 50 bytes. Therefore, the file path will be 50 bytes, and the rest of the bytes will be terminated. Finally, it returns a new file. It is mainly supported as a file descriptor as well.

main.py
data.txt
#Import OS module
import os

# Opening and printing the size of "file.txt"  
file = open("data.txt", "a")
#getsize() method is used to get the size of the file.txt
size1 = os.path.getsize('data.txt')
#Print the size of the file in bytes
print (f"The file size is {size1} bytes")

# Truncate the file up to 40 bytes and find the size again
file.truncate(50)

#Getsize() method used gain to get the size of the file
size2 = os.path.getsize('data.txt')
#Print the size again
print (f"The file size is {size2} bytes")

# Close the file
file.close()

Explanation

  • Line 2: We import the OS module.
  • Line 5: We open the file named data.txt.
  • Line7: We get the size of the file with the getsize() method.
  • Line 9: We print the file's size in bytes. We then use the truncate method and add 50 bytes to its size.
  • Line 15: We get the size of a file to distinguish the difference.
  • Line 17: We see the difference before using the truncate method and after using it. 

RELATED TAGS

os.truncate
python programming
os module
communitycreator

Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.

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