init/docs/gcron.md

Gcron

Gcron is a small daemon that executes batch commands once a certain condition is met.

In a typical installation, it reads configuration files from /etc/gcron.d. If used together with the init system in this package, the service command can be used to administer symlinks in that directory, pointing to /usr/share/init/<name>.gcron.

Each file in the configuration directory represents a single scheduled batch job. The syntax and most of the keywords are similar to initd service files (See services.md).

Cron Style Patterns

The following keywords can be used to specify classic cron style patterns for when a job should be run:

• hour
• minute
• dayofmonth
• dayofweek
• month

For each of those keywords, a comma separated sequence of times can be specified. Time ranges can be specified using the syntax <start>-<end>, or using * for every possible value. A sequence (either range or star) can be suffixed with /<step> to specify an increment. For instance, minute */5 means every five minutes and minute 15-30/2 means every two minutes between quarter past and half past.

In addition to numeric values, the keywords dayofweek and month allow specifying 3 letter, uppercase week day and moth names such as MON, TUE, etc and JAN, FEB, ...

The job is only run when all specified conditions are met. Omitting a field is the same as specifying *.

Named Intervals

Alternatively to the above, the keyword interval can be used. The following intervals can be specified:

• yearly or annually means on every January the first at midnight.
• monthly means on every first of the month at midnight.
• weekly means every Sunday at midnight.
• daily means every day at midnight.
• hourly means every first minute of the hour.

Command Specification

To specify what should be done once the condition is met, the following keywords can be used:

• exec - the command to run. Multiple commands can be grouped using curly braces.
• user - a user name or ID to set before running the commands.
• group - a group name or ID to set before running the commands.
• tty - similar to init service files, the controlling tty or output file for the batch commands. Like init service files, the truncate keyword can be used.