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 randomization. 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, especially 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)