Batch File Renamer

Powerful batch file renaming with patterns, regex, and preview.

When to Use

• Renaming hundreds of photos from IMG_001.jpg to Vacation_2025_001.jpg
• Adding timestamps to log files
• Cleaning up messy download folders
• Standardizing naming conventions across projects
• Sequential numbering for ordered content
• Removing special characters from filenames

Quick Start

Basic Rename

import os
import re
from datetime import datetime

def batch_rename(directory, pattern, replacement):
    """
    Rename files matching pattern
    
    Args:
        directory: Path to files
        pattern: Regex pattern to match
        replacement: Replacement string
    """
    renamed = []
    for filename in os.listdir(directory):
        new_name = re.sub(pattern, replacement, filename)
        if new_name != filename:
            old_path = os.path.join(directory, filename)
            new_path = os.path.join(directory, new_name)
            os.rename(old_path, new_path)
            renamed.append((filename, new_name))
    return renamed

# Example: Add prefix
batch_rename('./photos', r'^(.*)$', r'Vacation_2025_\1')

Sequential Numbering

def number_files(directory, prefix='', digits=3, extension=None):
    """Add sequential numbers to files"""
    files = sorted([f for f in os.listdir(directory) 
                   if extension is None or f.endswith(extension)])
    
    renamed = []
    for i, filename in enumerate(files, 1):
        old_path = os.path.join(directory, filename)
        ext = os.path.splitext(filename)[1]
        new_name = f"{prefix}{str(i).zfill(digits)}{ext}"
        new_path = os.path.join(directory, new_name)
        os.rename(old_path, new_path)
        renamed.append((filename, new_name))
    
    return renamed

# Usage
number_files('./downloads', prefix='Project_', digits=3)
# Result: Project_001.pdf, Project_002.jpg, ...

Add Timestamps

def add_timestamp(directory, date_format='%Y%m%d'):
    """Add date prefix to files"""
    timestamp = datetime.now().strftime(date_format)
    
    for filename in os.listdir(directory):
        old_path = os.path.join(directory, filename)
        name, ext = os.path.splitext(filename)
        new_name = f"{timestamp}_{name}{ext}"
        new_path = os.path.join(directory, new_name)
        os.rename(old_path, new_path)

# Usage
add_timestamp('./logs')
# Result: 20250303_error.log, 20250303_debug.log

Preview Mode (Safe)

def preview_rename(directory, pattern, replacement):
    """Preview changes without renaming"""
    changes = []
    for filename in os.listdir(directory):
        new_name = re.sub(pattern, replacement, filename)
        if new_name != filename:
            changes.append(f"{filename} -> {new_name}")
    return changes

# Preview first
preview = preview_rename('./files', r'IMG_(\d+)', r'Photo_\1')
for change in preview:
    print(change)

Common Patterns

Best Practices

1. Always preview first - Use preview_rename() before actual rename
2. Backup important files - Renaming is irreversible
3. Test on single file - Verify pattern works as expected
4. Use regex groups - Capture parts of filename with (\d+) etc.

Safety Features

def safe_rename(directory, pattern, replacement, dry_run=True):
    """Safe rename with dry-run option"""
    changes = []
    
    for filename in os.listdir(directory):
        new_name = re.sub(pattern, replacement, filename)
        if new_name != filename:
            changes.append((filename, new_name))
    
    if dry_run:
        print("DRY RUN - Changes that would be made:")
        for old, new in changes:
            print(f"  {old} -> {new}")
        return changes
    else:
        for old, new in changes:
            os.rename(
                os.path.join(directory, old),
                os.path.join(directory, new)
            )
        return changes