Cross-Platform File Timestamp Retrieval in Python

Introduction

In software development, understanding when a file was created or modified is often crucial. Whether it’s for auditing purposes, version control, or simply tracking changes, being able to retrieve these timestamps programmatically can save time and effort. This tutorial will guide you through obtaining creation and modification dates/times of files in Python in a cross-platform manner, covering Windows, macOS, and Linux systems.

File Timestamps: Basics

Every file on your filesystem has associated metadata that includes timestamps:

• Modification Time (mtime): The time when the content of the file was last modified.
• Creation Time (ctime): On Windows, this is the time when the file was created. On Unix-like systems (macOS and Linux), ctime represents the last time the file’s metadata or attributes were changed.

Retrieving Modification Dates

Retrieving a file’s modification date is straightforward across different platforms using Python’s standard library:

• Use os.path.getmtime(path) to get the modification timestamp as a Unix timestamp.
• Convert this timestamp into a human-readable format using datetime.datetime.fromtimestamp().

import os
from datetime import datetime

def get_modification_date(file_path):
    mod_time = os.path.getmtime(file_path)
    return datetime.fromtimestamp(mod_time)

file_path = 'example.txt'
print(f"Last modified: {get_modification_date(file_path)}")

Handling Creation Dates

Windows

On Windows, the creation time is directly available through os.path.getctime(path), which retrieves it as a Unix timestamp.

import os
from datetime import datetime

def get_creation_date_windows(file_path):
    create_time = os.path.getctime(file_path)
    return datetime.fromtimestamp(create_time)

file_path = 'example.txt'
print(f"Created: {get_creation_date_windows(file_path)}")

macOS and Some Unix-based Systems

macOS, along with some Unix-like systems, provides creation time via the st_birthtime attribute in the result of os.stat(path).

import os
from datetime import datetime

def get_creation_date_unix(file_path):
    stat_info = os.stat(file_path)
    try:
        return datetime.fromtimestamp(stat_info.st_birthtime)
    except AttributeError:
        print("Birth time not available.")
        return None

file_path = 'example.txt'
print(f"Created: {get_creation_date_unix(file_path)}")

Linux

Linux presents a challenge, as the kernel does not universally expose file creation times. However, you can retrieve modification times or use alternative methods if specific filesystems (like ext4) store this data.

import os
from datetime import datetime

def get_creation_date_linux(file_path):
    stat_info = os.stat(file_path)
    # Fallback to the last modification time
    return datetime.fromtimestamp(stat_info.st_mtime)

file_path = 'example.txt'
print(f"Created (Linux): {get_creation_date_linux(file_path)}")

Cross-Platform Approach

To handle file timestamps across different platforms, you can create a unified function that determines the operating system and retrieves the appropriate timestamp.

import os
from datetime import datetime
import platform

def get_file_timestamps(path):
    creation_time = modification_time = None
    
    if platform.system() == 'Windows':
        creation_time = datetime.fromtimestamp(os.path.getctime(path))
    else:
        stat_info = os.stat(path)
        try:
            creation_time = datetime.fromtimestamp(stat_info.st_birthtime)
        except AttributeError:
            pass  # Not available, so we don't set it
        modification_time = datetime.fromtimestamp(stat_info.st_mtime)

    return {
        "creation": creation_time,
        "modification": modification_time or datetime.fromtimestamp(os.path.getmtime(path))
    }

file_path = 'example.txt'
timestamps = get_file_timestamps(file_path)
print(f"Created: {timestamps['creation']}")
print(f"Modified: {timestamps['modification']}")

Conclusion

By leveraging Python’s built-in libraries, you can effectively retrieve file creation and modification timestamps across various operating systems. While handling these differences can be complex due to the platform-specific nature of file metadata, using conditional logic based on platform.system() allows for a seamless cross-platform experience.