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Show HN: Cronexpr, a Rust library to parse and iter crontab expression

160 points by tison

by cuu508

1 subcomments

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.

by the_duke

1 subcomments

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

by epage

1 subcomments

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

by Black616Angel

4 subcomments

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

by 1oooqooq

2 subcomments

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

by qwertox

2 subcomments

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/...

by Annatar

0 subcomment

[dead]

by faangguyindia

1 subcomments

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.