Python Compare File Sizes and Modification Times

This Python tutorial explains Compare File Sizes and Modification Times. Follow the example, inspect the output, and practise an input change so you understand the behavior rather than simply copying the syntax.

What This Feature Does

Read file metadata to compare modification time and size.

Path.stat() supplies a stat_result with fields such as st_size (bytes) and st_mtime (timestamp). Modification time can be affected by copying, synchronization and timestamp precision; it does not prove that file contents are identical.

When to Use It

This technique belongs to safe file automation. It is useful when the input, operation and expected outcome are known. Start with a small controlled example before integrating it into a larger workflow.

Step-by-Step Python Example

Read the code once before running it. Notice which values are inputs, which function or method performs the work, and whether the result is returned or stored by changing an existing object.

from pathlib import Path
from tempfile import TemporaryDirectory

with TemporaryDirectory() as directory_name:
    first_file = Path(directory_name) / "first.txt"
    second_file = Path(directory_name) / "second.txt"
    first_file.write_bytes(b"abcd")
    second_file.write_bytes(b"abcde")
    first_info = first_file.stat()
    second_info = second_file.stat()
    print(first_info.st_size, second_info.st_size)
    print(first_info.st_size < second_info.st_size)

Understanding the Code

First, the imports make pathlib, tempfile available. They provide the filesystem, data or standard-library functions used later.
Find the call TemporaryDirectory(). Its parameters determine the specific operation demonstrated in the title.
Its purpose is to read file metadata to compare modification time and size. Compare this description against the result printed by the program.
The sample uses TemporaryDirectory() so any practice files are removed after the context ends; it does not work on your real documents.
The print() expressions display a checkable outcome. Print values and exception names are not substitutes for the program result itself.

Expected Output

4 5
True

Each printed line corresponds to a separate observation in the program. Use the lines to distinguish returned data, changes to existing objects, and status checks.

Important Details and Edge Cases

Use a content hash or byte-by-byte comparison when identity matters; timestamps and sizes are only quick metadata signals.

Before applying this to real documents, check whether the method reads data, creates a new file, moves it, or overwrites an existing file. Work in a disposable test directory first and handle OSError-related failures in applications.

Practice: Try It Yourself

Compare two temporary files by size and then by their actual byte content.

Begin by copying the example into a separate practice file. Change one input at a time, run it again, and describe why the result changed. If the exercise writes or deletes files, keep it inside a temporary test folder.

Official Python Documentation

For the complete reference, see the Python standard library documentation.

Common Beginner Mistakes

Treating equal file sizes as evidence that the byte contents are equal.
Comparing floating timestamps without accounting for filesystem resolution or clock differences.
Before applying this to real documents, check whether the method reads data, creates a new file, moves it, or overwrites an existing file. Work in a disposable test directory first and handle OSError-related failures in applications.

Key Takeaways

Read file metadata to compare modification time and size.
Path.stat() supplies a stat_result with fields such as st_size (bytes) and st_mtime (timestamp). Modification time can be affected by copying, synchronization and timestamp precision; it does not prove that file contents are identical.
Avoid this common pitfall: Treating equal file sizes as evidence that the byte contents are equal.