Regex File Renamer
This utility automates batch file renaming using Regular Expressions (Regex). It allows you to search for complex patterns in filenames and replace them with a new format using capture groups.
Modules Used:
- re: To handle regular expression matching and substitution.
os: To perform the actual file renaming.- argparse: To handle command-line arguments.
The Code
Save this as regex_rename.py.
import re
import os
import argparse
import sys
def batch_rename(directory, pattern, replacement, dry_run=False):
if not os.path.exists(directory):
print(f"Error: Directory '{directory}' not found.")
return
print(f"Scanning '{directory}'...")
print(f"Pattern: r'{pattern}' -> '{replacement}'")
count = 0
try:
# Compile regex for performance
regex = re.compile(pattern)
except re.error as e:
print(f"Error: Invalid regex pattern. {e}")
return
for filename in os.listdir(directory):
# Skip directories
if os.path.isdir(os.path.join(directory, filename)):
continue
# Check for match
if regex.search(filename):
# Generate new name
# re.sub uses \1, \2 etc. for backreferences to capture groups
new_name = regex.sub(replacement, filename)
if new_name == filename:
continue
old_path = os.path.join(directory, filename)
new_path = os.path.join(directory, new_name)
if os.path.exists(new_path):
print(f"Skipping: '{new_name}' already exists.")
continue
if dry_run:
print(f"[DRY RUN] Rename: '{filename}' -> '{new_name}'")
else:
try:
os.rename(old_path, new_path)
print(f"Renamed: '{filename}' -> '{new_name}'")
except OSError as e:
print(f"Error renaming '{filename}': {e}")
count += 1
if count == 0:
print("No files matched the pattern.")
else:
print(f"\nProcessed {count} files.")
if __name__ == "__main__":
parser = argparse.ArgumentParser(description="Batch File Renamer using Regex")
parser.add_argument("directory", help="Target directory")
parser.add_argument("pattern", help="Regex pattern to match (e.g., 'img_(\d+)')")
parser.add_argument("replacement", help="Replacement pattern (e.g., 'photo_\\1')")
parser.add_argument("--dry-run", action="store_true", help="Show what would happen without renaming")
args = parser.parse_args()
batch_rename(args.directory, args.pattern, args.replacement, args.dry_run)Usage
# Preview changes (Dry Run)
# Rename 'img_001.jpg' to 'photo_001.jpg'
# Note: Use \\1 for backreferences in the command line to ensure python receives \1
python regex_rename.py ./photos "img_(\d+)" "photo_\\1" --dry-run
# Execute renaming
# Change date format from '2023-01-01_report.txt' to 'report_2023-01-01.txt'
python regex_rename.py ./docs "(\d{4}-\d{2}-\d{2})_(.*)\.txt" "\\2_\\1.txt"