check_uniqueness_of_uids.py

# requires python-frontmatter==1.0.0

import frontmatter
import glob
import sys

uids = {}
files = glob.glob('**/*.markdown')
files.extend(glob.glob('**/*.md'))
for file in files:
  post = frontmatter.load(file)
  if 'uid' in post.keys():
    uid = post['uid']
    f = uids.get(uid, [])
    f.append(file)
    uids[uid] = f
error = False
for uid in uids:
  if len(uids[uid]) > 1:
    error = True
    print(f'{uid} used in multiple files:')
    for file in uids[uid]:
      print(f'  {file}')
if error:
  sys.exit(1)