Looks well done. I like how the docs describe every syntax feature, and every non-standard feature in detail. Hat tip to implementing Vixie's "*,10" quirk, and to handling DST.

There is also a cron parser library from Cloudflare which is used for their cron jobs: https://github.com/cloudflare/saffron

After working with Jenkins which has "hashed value" support for automatic staggering of jobs, I think its essential in any cron syntax evaluater.

Main drawback is the need for timestamps. Most crontab files or expressions I've seen didn't have them.

isn't cron removed from most distros? now you need 3 or 4 different files for systemd-cronie

If you're into Python, APScheduler is the way to go.

It also has a cron scheduler [0] which includes scheduling down to seconds and perfectly integrates with asyncio [1].

  async def myfunc():
      print(f"\n{Fore.GREEN}Readout triggered at { datetime.now().strftime('%H:%M:%S') }{COLORS_RESET}\n")
      await disk_temperatures_handler.readout(storage)
  
  scheduler = AsyncIOScheduler()
  storage['scheduler'] = scheduler
  
  scheduler.add_job(myfunc, CronTrigger(second='*/15'), id='readout_job')
  scheduler.start()

You can also modify the interval on-the-fly.

[0] https://apscheduler.readthedocs.io/en/3.x/modules/triggers/c...

[1] https://apscheduler.readthedocs.io/en/3.x/modules/executors/...

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I've LLM based crontab bot. Where I simply write stuff like "run my backupBitBuckettoDropbox.sh from home directory at 3am everyday".

I never really liked cronjob expressions.