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https://github.com/mongoose-os-libs/cron
https://github.com/mongoose-os-libs/cron
Last synced: about 2 months ago
JSON representation
- Host: GitHub
- URL: https://github.com/mongoose-os-libs/cron
- Owner: mongoose-os-libs
- License: other
- Created: 2017-10-24T11:40:39.000Z (almost 7 years ago)
- Default Branch: master
- Last Pushed: 2022-03-29T18:58:41.000Z (over 2 years ago)
- Last Synced: 2024-05-31T12:35:13.587Z (4 months ago)
- Language: C
- Size: 461 KB
- Stars: 6
- Watchers: 7
- Forks: 8
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-mongoose-os - cron
README
# A Cron Mongoose OS library
## Overview
This library implement cron core functionality. See also:
[crontab](https://github.com/mongoose-os-libs/crontab).
This library supports classic cron expressions with additional field for the
seconds, plus a few extras. We'll get back to the extras later, let's start
with regular cron expressions.
### Classic cron expressions.
Each expression contains 6 fields:
- seconds, `0-59`
- minutes, `0-59`
- hours, `0-23`
- day of month, `1-31`
- month, `1-12` or `JAN-DEC`
- day of week `0-6` or `SUN-SAT`
Each field can contain multiple values separated with commas, and/or ranges
determined by the beginning of the range, a hyphen, and the ending of the
range. For example, for the day of week, it could be `MON-THU,SAT`
A slash can be used to specify intervals: e.g. `*/5` in seconds field means
"every 5 seconds".
Each field can contain an asterisk `*` which means "any value".
Examples:
- `*/15 * 1-4 * * *` : Run every 15 seconds from 1 to 4 hours;
- `0 */2 1-4 * * *` : Run every two minutes from 1 to 4 hours;
- `0 0 7 * * MON-FRI` : Run at 7:00 every working day;
- `0 30 23 30 * *` : Run at 23:30 every 30th day of month.
### Randomized cron expressions
It's possible to specify the time range in which a job will run certain number
of times.
For example, this:
```
@random:{"from":"10 * * * * *", "to":"50 * * * * *", "number":5}
```
means that the cron job will be fired in between of 10 and 50 seconds of every
minute, and the total number of invocations in that 40-second time window will
be approximately 5. It's not guaranteed to be exactly 5 though: might be a bit
less or more.
Another example: approximately 10 invocations in between of 08:00 and 22:00 on
working days:
```
@random:{"from":"0 0 8 * * MON-FRI", "to":"0 0 22 * * MON-FRI", "number":10}
```
Note that the timeout between `from` and `to` should always be the same.
For example, this would make no sense:
```
@random:{"from":"0 0 8 * * MON-FRI", "to":"0 0 22 * * *", "number":10}
```
Currently these cases are not checked yet, so the above expression will just
result in incorrect behavior.
### Sunrise/sunset
Finally, instead of specifying exact time with the first three fields (seconds,
minutes, hours) one could use `@sunrise` / `@sunset`, plus optional offset like
`+2h45m` or `-1.5h`.
For that to work, the device needs to have latitude/longtitude and timezone
configured.
Examples:
- `@sunrise * * MON-FRI` : Run at the sunrise on working days;
- `@sunset-1h30m 1 * *` : Run 1.5 hours before the sunset every 1th day of month;
- `@sunset * * *` : Run at the sunset every day
As a shortcut for the last case, when all fields are `*`, these fields can be
omitted. Thus, more valid examples:
- `@sunrise`
- `@sunset`
- `@sunset+3h`