queuedefs -- scheduling information for cron queues


a|b|c.[njobsj] [nicen] [waitw]


The queuedefs file is read by the clock daemon, cron, and controls how jobs submitted with at, batch, and crontab are executed. Every job submitted by one of these programs is placed in a certain queue, and the behavior of these queues is defined in /usr/lib/cron/queuedefs.

Queues are designated by a single lower-case letter. The following queues have special significance:

a at queue
b batch queue
c cron queue

For a given queue, the queuedefs file specifies the maximum number of jobs that may be executing at one time (njobs), the priority at which jobs will execute (nice), and the how long cron will wait between attempts to run a job (wait). If njobs jobs are already running in a given queue when a new job is scheduled to begin execution, cron will reschedule the job to execute wait seconds later.

Each line of queuedefs gives parameters for one queue. The line must begin with a letter designating a queue, followed by a period (.). This is followed by the numeric values for njobs, nice, and wait, followed by the letters j, n, and w respectively. The values must appear in this order, although a value and its corresponding letter may be omitted entirely, in which case a default value is used. The default values are njobs = 100, nice = 2, and wait = 60.

The value for nice is added to the default priority of the job (a higher numerical priority results in a lower scheduling priority -- see nice(C)). Note that the nice value does not apply when the command is run by ``root''.


A typical queuedefs file might look like:
Here at is allowed to run four jobs at a time with a nice value of 1. Jobs will be rescheduled to run 60 seconds later if there is no room in the run queue. batch can run two jobs at a time with a nice value of 2, and a rescheduling period of 90 seconds.


full pathname of queuedefs

See also

at(C), cron(C), crontab(C), nice(C)
© 2005 The SCO Group, Inc. All rights reserved.
SCO OpenServer Release 6.0.0 -- 03 June 2005