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62 lines
2.3 KiB
Markdown
62 lines
2.3 KiB
Markdown
# Gcron
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Gcron is a small daemon that executes batch commands once a certain
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condition is met.
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In a typical installation, it reads configuration files from `/etc/gcron.d`.
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If used together with the init system in this package, the `service` command
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can be used to administer symlinks in that directory, pointing
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to `/usr/share/init/<name>.gcron`.
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Each file in the configuration directory represents a single scheduled batch
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job. The syntax and most of the keywords are similar to `initd` service files
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(See [services.md](services.md)).
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## Cron Style Patterns
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The following keywords can be used to specify classic cron style patterns for
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when a job should be run:
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* `hour`
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* `minute`
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* `dayofmonth`
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* `dayofweek`
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* `month`
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For each of those keywords, a comma separated sequence of times can be
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specified. Time ranges can be specified using the syntax `<start>-<end>`,
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or using `*` for every possible value. A sequence (either range or star)
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can be suffixed with `/<step>` to specify an increment.
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For instance, `minute */5` means every five minutes and `minute 15-30/2`
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means every two minutes between quarter past and half past.
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In addition to numeric values, the keywords `dayofweek` and `month` allow
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specifying 3 letter, uppercase week day and moth names such as `MON`, `TUE`,
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etc and `JAN`, `FEB`, ...
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The job is only run when all specified conditions are met. Omitting a field
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is the same as specifying `*`.
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## Named Intervals
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Alternatively to the above, the keyword `interval` can be used. The following
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intervals can be specified:
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* `yearly` or `annually` means on every January the first at midnight.
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* `monthly` means on every first of the month at midnight.
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* `weekly` means every Sunday at midnight.
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* `daily` means every day at midnight.
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* `hourly` means every first minute of the hour.
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## Command Specification
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To specify *what* should be done once the condition is met, the following
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keywords can be used:
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* `exec` - the command to run. Multiple commands can be grouped
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using curly braces.
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* `user` - a user name or ID to set before running the commands.
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* `group` - a group name or ID to set before running the commands.
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* `tty` - similar to init service files, the controlling tty or output file
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for the batch commands. Like init service files, the `truncate` keyword
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can be used.
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