CRONTABS(4) Crontabs users Manual CRONTABS(4)

NAME crontabs - configuration and scripts for running periodical jobs

SYNOPSIS run-parts <directory>

DESCRIPTION Crontabs is a historical name for the run-parts script and the system crontab. The run-parts script runs all executables in the specified directory.

The crontab file contains configuration which calls the run-parts script on files in the /etc/cron.{daily,weekly,monthly}/ directories.

Randomization of jobs can be configured in the /etc/sysconfig/run-parts file. To enable randomization of jobs, set the RANDOMIZE parameter to 1 and set the RANDOM parameter to an integer which determines a random seed. Additionally, you may configure the RANDOMTIME parameter (again, by specifying an integer) to provide an additional level of randomiza- tion. Jobs are not randomized when the RANDOM and RANDOMTIME parameters are set to 0. Values in these two parameters must be set to 1 or larger to provide a good enough randomization.

Randomization of cron jobs can be useful for shared networks, where multiple cron jobs executed at once can cause spikes in traffic, espe- cially during daily jobs. With randomized jobs, the workload is evenly distributed throughout the day.

EXAMPLE OF CONFIGURATION FILE RANDOMIZE=1 RANDOM=4 RANDOMTIME=8

SEE ALSO crontab(5)

Marcela Maláová 2012-08-29 CRONTABS(4)