man pages section 4: File Formats

queuedefs(4)

Name

queuedefs– queue description file for at, batch, and cron

Synopsis

/etc/cron.d/queuedefs

Description

The queuedefs file describes the characteristics of the queues managed by cron(1M). Each non-comment line in this file describes one queue. The format of the lines are as follows:

q.[njobj][nicen][nwaitw]

The fields in this line are:

q: 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 at(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 that 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 to give to all jobs in that queue that are not run with a user ID of super-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 the system-wide limit of jobs executing has been reached. The default value is 60.

Lines beginning with # are comments, and are ignored.

Examples

Example 1 Using a Queue Description File

#
#
a.4j1n
b.2j2n90w

This file specifies that the a queue, for at jobs, can have up to 4 jobs running simultaneously; those jobs will be run with a nice value of 1. As no nwait value was given, if a job cannot be run because too many other jobs are running cron will wait 60 seconds before trying again to run it.

The b queue, for batch(1) jobs, can have up to 2 jobs running simultaneously; those jobs will be run with a nice(1) value of 2. If a job cannot be run because too many other jobs are running, cron(1M) will wait 90 seconds before trying again to run it. All other queues can have up to 100 jobs running simultaneously; they will be run with a nice value of 2, and if a job cannot be run because too many other jobs are running cron will wait 60 seconds before trying again to run it.

Files

/etc/cron.d/queuedefs: queue description file for at, batch, and cron.