# Cron Module | Since | Origin / Contributor | Maintainer | Source | | :----- | :-------------------- | :---------- | :------ | | 2016-12-18 | [PhoeniX](https://github.com/djphoenix) | [PhoeniX](https://github.com/djphoenix) | [cron.c](../../app/modules/cron.c)| [Cron](https://en.wikipedia.org/wiki/Cron)-like scheduler module. !!! important This module needs RTC time to operate correctly. Do not forget to include the [`rtctime`](rtctime.md) module **and** initialize it properly. !!! important The cron expression has to be in GMT/UTC! ## cron.schedule() Creates a new schedule entry. #### Syntax `cron.schedule(mask, callback)` #### Parameters - `mask` - [crontab](https://en.wikipedia.org/wiki/Cron#Overview)-like string mask for schedule - `callback` - callback `function(entry)` that is executed at the scheduled time #### Returns `cron.entry` sub module #### Example ```lua cron.schedule("* * * * *", function(e) print("Every minute") end) cron.schedule("*/5 * * * *", function(e) print("Every 5 minutes") end) cron.schedule("0 */2 * * *", function(e) print("Every 2 hours") end) ``` ## cron.reset() Removes all scheduled entries. #### Syntax `cron.reset()` #### Parameters none #### Returns nil # cron.entry Module ## cron.entry:handler() Sets a new handler for entry. #### Syntax `handler(callback)` #### Parameters - `callback` - callback `function(entry)` that is executed at the scheduled time #### Returns nil #### Example ```lua ent = cron.schedule("* * * * *", function(e) print("Every minute") end) ent:handler(function(e) print("New handler: Every minute") end) ``` ## cron.entry:schedule() Sets a new schedule mask. #### Syntax `schedule(mask)` #### Parameters - `mask` - [crontab](https://en.wikipedia.org/wiki/Cron#Overview)-like string mask for schedule #### Returns none #### Example ```lua ent = cron.schedule("* * * * *", function(e) print("Tick") end) -- Every 5 minutes is really better! ent:schedule("*/5 * * * *") ``` ## cron.entry:unschedule() Disables schedule. Disabled schedules may be enabled again by calling [`:schedule(mask)`](cron.md#cronentryschedule). #### Syntax `unschedule()` #### Parameters none #### Returns nil #### Example ```lua ent = cron.schedule("* * * * *", function(e) print("Tick") end) -- We don't need this anymore ent:unschedule() ```