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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/syscon-
              fig/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
       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)