Run as `python3 renamer.py /path/to/normalize`. Renames all files and subdirectories at specified root to be UNIX-friendly and not require any quoting.

renamer.py

#!/usr/bin/python3
import os
import re
import sys

try:
  PATH = sys.argv[1]
except IndexError:
  print("Usage: %s /path/to/normalize" % sys.argv[0])
  exit(0)
REPLACE_REGEX = re.compile(r'[^a-zA-Z0-9_.-]')

print("Normalizing directory tree at %s..." % PATH)
total = 0
for root, dirs, files in os.walk(PATH, topdown=False):
  norm_set = set()
  for i, orig in enumerate(files+dirs):
    norm = re.sub(REPLACE_REGEX, '_', orig.lower())
    if norm.startswith('-'):
      norm = norm.replace('-', '_', 1)
    if norm in norm_set:
      norm = '%s_%d' % (norm, i)
    norm_set.add(norm)
    if orig != norm:
      os.rename(os.path.join(root, orig), os.path.join(root, norm))
      total += 1
print("Operation finished, renamed %d files and directories" % total)