Mass rename files with python

rename.py

#!/usr/bin/env python3
import argparse
from glob import glob
import os
import re
import sys


def parse_args():
    parser = argparse.ArgumentParser('Rename files using regex')
    parser.add_argument('regex',
                        help="regex to apply to files (e.g. 's/regex/replace/')")
    parser.add_argument('files', nargs='+',
                        help='files to modify')
    parser.add_argument('-n', '--dry-run', action='store_true',
                        help="print outcome, don't rename")
    parser.add_argument('-v', '--verbose', action='store_true',
                        help='verbose output')
    parser.add_argument('-x', '--ignore-ext', action='store_true',
                        help='ignore file extensions')
    parser.add_argument('-i', '--interactive', action='store_true',
                        help='prompt before overwriting')
    return parser.parse_args()


def confirm(msg):
    return input('{} [Y/n] '.format(msg)).lower() == 'y'


def error(*msg):
    print(*msg, file=sys.stderr)

args = parse_args()
split = args.regex.split('/')

if len(split) != 4 or split[0] != 's':
    error("Invalid regex: '{}'".format(args.regex))
    sys.exit(1)

_, search, replace, flags = split

flags = re.I if flags == 'i' else 0

# This bit is for Windows, where wildcards aren't expanded
if any('*' in f for f in args.files):
    files = []
    for f in args.files:
        files += glob(f)
else:
    files = args.files

for f in files:
    if not os.path.exists(f):
        error("No such file or directory: '{}'".format(f))
        continue

    if args.ignore_ext:
        f, ext = os.path.splitext(f)

    output = re.sub(search, replace, f, flags=flags)

    # Add extension back
    if args.ignore_ext:
        f += ext
        output += ext

    # No change, don't care
    if f == output:
        continue

    # Check for conflicts in interactive mode
    if (args.interactive and
            not args.dry_run and
            os.path.exists(output) and
            not confirm('overwrite {}?'.format(output))):
        continue

    if args.dry_run or args.verbose:
        print('{} -> {}'.format(f, output))

    if not args.dry_run:
        os.rename(f, output)