queuedefs(4)

queuedefs -- queue definition file for crontab and at

Synopsis

   /etc/cron.d/queuedefs

Description

The queuedefs file defines the characteristics of the queues managed by cron (1M). Each non-comment line in this file describes one queue. The format of each line is:

   queue.[njobj][nicen][nwaitw]

The fields in this line are:

queue: The name of the queue. a is the default queue for jobs started by at (1); b is the default queue for jobs started by batch (see batch (1)); c is the default queue for jobs run from a crontab (1) file.
njob: The maximum number of jobs that can be run simultaneously in queue. If more than njob jobs are ready to run, only the first njob jobs will be run, and the others will be run as jobs that are currently running terminate. The default value is 100.
nice: The nice (1) value for all jobs in queue that are not run with a user ID of a privileged user. The default value is 2.
nwait: The number of seconds to wait before rescheduling a job that was deferred because more than njob jobs were running in that job's queue, or because more than 25 jobs were running in all the queues. The default value is 60.

Lines beginning with # are comments, and are ignored.

Files

/etc/default/cron: Control logging of cron jobs.
/etc/cron.d/queuedefs: Specify concurrency, priority, and retry interval.

References

at(1), cron(1M), crontab(1), nice(1)

Examples

The queuedefs file supplied with System V is:

   a.4j1n
   b.2j2n90w

The first line specifies how at(1) jobs are to be handled:

Start a maximum of 4 concurrent jobs per user.
Use a nice(1) value of 1.
Do not retry jobs that cannot start because fork(2) fails.

The second line specifies how crontab(1) jobs are to be handled:

Start a maximum of 2 concurrent jobs per user.
Use a nice(1) value of 2.
Wait 90 seconds, then try again to start jobs that cannot start because fork(2) fails.