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maennchen committed Nov 14, 2022
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121 changes: 121 additions & 0 deletions docs/cheatsheets/cron_notation.cheatmd
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# Cron Notation Cheatsheet

## Overview

```
[:second] :minute :hour :day :month :weekday :year
```

```
[*] * * * * * *
```

```
| | | | | | |
| | | | | | └-- Year (range: 1900-3000)
| | | | | └--------- Day of the Week (range: 0-7, 0 sunday, 1 monday, ..., 7 sunday)
| | | | └----------------- Month of the Year (range: 1-12)
| | | └----------------------- Day of the Month (range: 1-31)
| | └----------------------------- Hour (range: 0-23)
| └------------------------------------ Minute (range: 0-59)
└--------------------------------------------- Second (range: 0-59)
```

Seconds are only present in a cron expression if `extended` is enabled.

## Operators

| Operator | Description | Allowed in |
| -------- | ------------------------------------------------------------ | ----------------- |
| `*` | all values | everywhere |
| `,` | separate individual values | everywhere |
| `-` | a range of values | everywhere |
| `/` | divide a value into steps | everywhere |
| `#` | nth occurance | `weekday` |
| `L` | last occurance | `weekday` / `day` |
| `W` | specifies the `weekday` nearest the given `day` of the month | `day` |
| `LW` | last `weekday` of the month | `day` |

## Expressions

{: .col-2}

### Special Values

{: .list-4}

#### Days

specify a day by name in the `weekday` field

- `MON`
- `TUE`
- `WED`
- `THU`
- `FRI`
- `SAT`
- `SUN`

#### Months

specify a month by name in the `month` field

- `JAN`
- `FEB`
- `MAR`
- `APR`
- `MAY`
- `JUN`
- `JUL`
- `AUG`
- `SEP`
- `OCT`
- `NOV`
- `DEC`

### Special Expressions

| Expression | Description |
| ----------- | ----------------------------------------- |
| `@reboot` | once after start of application |
| `@yearly` | once at the start of every year |
| `@annually` | same as `@yearly` |
| `@monthly` | once at the start of every month |
| `@weekly` | once at the start of every week on sunday |
| `@dayily` | once at the start of every day |
| `@midnight` | same as `@daily` |
| `@hourly` | once at the start of every hour |
| `@minutely` | once at the start of every minute |
| `@secondly` | once at the start of every second |

## Examples

| Expression | Description |
| -------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `0 0 12 * * *` | Fire at 12:00 p.m. (noon) every day |
| `0 15 10 * * *` | Fire at 10:15 a.m. every day |
| `0 15 10 * * *` | Fire at 10:15 a.m. every day |
| `0 15 10 * * * *` | Fire at 10:15 a.m. every day |
| `0 15 10 * * * 2012` | Fire at 10:15 a.m. every day during the year 2012 |
| `0 * 14 * * *` | Fire every minute starting at 2:00 p.m. and ending at 2:59.p.m., every day |
| `0 0/5 14 * * *` | Fire every five minutes starting at 2:00 p.m. and ending at 2:55 p.m., every day |
| `0 0/5 14,18 * * *` | Fire every five minutes starting at 2:00 p.m. and ending at 2:55 p.m., and fire every five minutes starting at 6:00 p.m. and ending at 6:55 p.m., every day |
| `0 0-5 14 * * *` | Fire every minute starting at 2:00 p.m. and ending at 2:05.p.m., every day |
| `0 10,44 14 * 3 WED` | Fire at 2:10 p.m. and at 2:44 p.m. every Wednesday in the month of March |
| `0 15 10 * * MON-FRI` | Fire at 10:15 a.m. every Monday, Tuesday, Wednesday, Thursday and Friday |
| `0 15 10 15 * *` | Fire at 10:15 a.m. on the 15th day of every month |
| `0 15 10 15 * *` | Fire at 10:15 a.m. on the last day of every month |
| `0 15 10 * * 6L` | Fire at 10:15 a.m. on the last Friday of every month |
| `0 15 10 * * 6L 2011-2014` | Fire at 10:15 a.m. on every last Friday of every month during the years 2011, 20012, 2014, and 2014 |
| `0 15 10 * * 6#3` | Fire at 10:15 a.m. on the third Friday of every month |
| `0 0 12 1/5 * *` | Fire at 12:00 p.m. (noon) every five days every month, starting on the first day of the month |
| `0 11 11 11 11 *` | Fire every November 11th at 11:11 a.m. |

## Helpful Tools / further documentation

- [crontab guru](https://crontab.guru/)
- https://en.wikipedia.org/wiki/Cron
- https://linux.die.net/man/5/crontab
- https://www.netiq.com/documentation/cloud-manager-2-5/ncm-reference/data/bexyssf.html
- http://www.quartz-scheduler.org/documentation/quartz-2.3.0/tutorials/crontrigger.html
- https://docs.oracle.com/cd/E12058_01/doc/doc.1014/e12030/cron_expressions.htm
2 changes: 1 addition & 1 deletion mix.exs
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Expand Up @@ -59,7 +59,7 @@ defmodule Crontab.Mixfile do

defp docs do
[
extras: ["README.md"],
extras: ["README.md", "docs/cheatsheets/cron_notation.cheatmd"],
main: "readme",
source_url: @source_url,
source_ref: "v" <> @version
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