CRONTABS(4)						      Crontabs users' Manual						       CRONTABS(4)

NAME

       crontabs - configuration and scripts for running periodical jobs

SYNOPSIS

       run-parts [--list|--test]<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.  Run-parts runs all executables in the specified directory.  The execution of files can be allowed or denied	by  creating  file
       jobs.allow or jobs.deny which worked similar as other allow/deny config files. The file must be created in the specified directory.

       --list print names of all files (not limited to executables), but don't run them. This option can't be used with test option.

       --test print names of files, which would be run.

	      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  RAN-
	      DOMTIME  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

       Historically the crontab file contained configuration which called run-parts on files  in  cron.{daily,weekly,monthly}  directories.  These
       jobs  are  now  run  indirectly	through  anacron  to prevent conflicts between cron and anacron.  That means the anacron package has to be
       installed if the jobs in these directories should be running. Refer to the anacron(8) how to limit the time of day of the job execution.

EXAMPLE

       /etc/cron.daily/jobs.deny could contain for example 0logwatch which forbid execution of this script.

SEE ALSO

       anacron(8), crontab(5)

Marcela Malaova 						    2012-08-29							       CRONTABS(4)