1CRONTABS(4) Crontabs users' Manual CRONTABS(4)
2
3
4
6 crontabs - configuration and scripts for running periodical jobs
7
9 run-parts [--list|--test]<directory>
10
12 Crontabs is a historical name for the run-parts script and the system
13 crontab. The run-parts script runs all executables in the specified
14 directory. Run-parts runs all executables in the specified directory.
15 The execution of files can be allowed or denied by creating file
16 jobs.allow or jobs.deny which worked similar as other allow/deny config
17 files. The file must be created in the specified directory.
18
19 --list print names of all files (not limited to executables), but don't
20 run them. This option can't be used with test option.
21
22 --test print names of files, which would be run.
23
24 Randomization of jobs can be configured in the /etc/syscon‐
25 fig/run-parts file. To enable randomization of jobs, set the
26 RANDOMIZE parameter to 1 and set the RANDOM parameter to an
27 integer which determines a random seed. Additionally, you may
28 configure the RANDOMTIME parameter (again, by specifying an
29 integer) to provide an additional level of randomization. Jobs
30 are not randomized when the RANDOM and RANDOMTIME parameters are
31 set to 0. Values in these two parameters must be set to 1 or
32 larger to provide a good enough randomization.
33
34 Randomization of cron jobs can be useful for shared networks,
35 where multiple cron jobs executed at once can cause spikes in
36 traffic, especially during daily jobs. With randomized jobs, the
37 workload is evenly distributed throughout the day.
38
39
41 RANDOMIZE=1
42 RANDOM=4
43 RANDOMTIME=8
44
45 Historically the crontab file contained configuration which called run-
46 parts on files in cron.{daily,weekly,monthly} directories. These jobs
47 are now run indirectly through anacron to prevent conflicts between
48 cron and anacron. That means the anacron package has to be installed
49 if the jobs in these directories should be running. Refer to the
50 anacron(8) how to limit the time of day of the job execution.
51
52
54 /etc/cron.daily/jobs.deny could contain for example 0logwatch which
55 forbid execution of this script.
56
58 anacron(8), crontab(5)
59
60
61
62Marcela Mašláňová 2012-08-29 CRONTABS(4)