1CRONTABS(4)                 Crontabs users' Manual                 CRONTABS(4)
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NAME

6       crontabs - configuration and scripts for running periodical jobs
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SYNOPSIS

9       run-parts [--list|--test]<directory>
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DESCRIPTION

12       Crontabs  is  a historical name for the run-parts script and the system
13       crontab. The run-parts command runs all executables  in  the  specified
14       directory.  The execution of files can be allowed or denied by creating
15       file jobs.allow or jobs.deny which worked similar as  other  allow/deny
16       config files. The file must be created in the specified directory.
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18       --list print names of all files (not limited to executables), but don't
19              run them. This option can't be used with test option.
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21       --test print names of files, which would be run.
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23              Randomization of jobs can  be  configured  in  the  /etc/syscon‐
24              fig/run-parts  file.  To  enable  randomization of jobs, set the
25              RANDOMIZE parameter to 1 and set  the  RANDOM  parameter  to  an
26              integer  which  determines  a random seed. Additionally, you may
27              configure the RANDOMTIME  parameter  (again,  by  specifying  an
28              integer)  to  provide an additional level of randomization. Jobs
29              are not randomized when the RANDOM and RANDOMTIME parameters are
30              set  to  0.  Values  in these two parameters must be set to 1 or
31              larger to provide a good enough randomization.
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33              Randomization of cron jobs can be useful  for  shared  networks,
34              where  multiple  cron  jobs executed at once can cause spikes in
35              traffic, especially during daily jobs. With randomized jobs, the
36              workload is evenly distributed throughout the day.
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EXAMPLE OF CONFIGURATION FILE

40       RANDOMIZE=1
41       RANDOM=4
42       RANDOMTIME=8
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44       Historically the crontab file contained configuration which called run-
45       parts on files in cron.{daily,weekly,monthly} directories.  These  jobs
46       are  now  run  indirectly  through anacron to prevent conflicts between
47       cron and anacron.  That means the anacron package has to  be  installed
48       if  the  jobs  in  these  directories  should  be running. Refer to the
49       anacron(8) how to limit the time of day of the job execution.
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EXAMPLE

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

57       anacron(8), crontab(5)
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61Marcela Mašláňová                 2012-08-29                       CRONTABS(4)
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