Batch File Renamer

Batch File Renamer

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

When to Use

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

| Pattern | Description | Example | |---------|-------------|---------| | r'^IMG_(\d+)' | Match IMG_ prefix | IMG_001.jpg | | r'\s+' | Replace spaces | My File.txt → My_File.txt | | r'[^\w\.]' | Remove special chars | file@#$%.txt → file.txt | | r'\.jpeg$' | Change extension | .jpeg → .jpg |

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

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)

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.