Cron Explainer by langbot-team

# Cron Explainer

Explain a 5-field cron expression and list the next N run times.

```
python scripts/run.py "*/15 9-17 * * 1-5"
python scripts/run.py "0 0 1 * *" -n 3
python scripts/run.py @daily
echo "30 4 * * 6" | python scripts/run.py -
```

Pure Python stdlib (`datetime`). Supports `*`, `,`, `-`, `/` and `@aliases`.


---
name: cron-explainer
display_name: Cron Explainer
description: "Explain a 5-field cron expression in plain English and list the next N run times. Triggers: explain cron, cron schedule, what does this cron do, crontab, next run times."
---

# Cron Explainer

Turn a cron expression into plain English and show when it fires next.

## When to use
The user has a crontab line (`*/15 9-17 * * 1-5`) or an alias (`@daily`) and wants to know what it means and the upcoming run times.

## How to use
Run `scripts/run.py` with the expression (quote it so the shell doesn't expand `*`):
- `python scripts/run.py "*/15 9-17 * * 1-5"` — explain + next 5 runs.
- `python scripts/run.py "0 0 1 * *" -n 3` — next 3 runs only.
- `python scripts/run.py @daily` — supports `@daily`, `@hourly`, `@weekly`, `@monthly`, `@yearly`, `@midnight`.
- `echo "30 4 * * 6" | python scripts/run.py -` — read from stdin.

Fields are minute, hour, day-of-month, month, day-of-week and support `*`, `,`, `-`, and `/`.

## Pitfalls
- Day-of-week uses 0=Sunday..6=Saturday. When both day-of-month and day-of-week are restricted, a run matches if **either** matches (standard cron OR behavior).
- Next-run search iterates minute-by-minute and is capped at one year; very sparse schedules may report no run found.
- Times are computed in the local timezone of the machine running the script.